Telocytes (TCs) are a newly discovered type of mesenchymal cell that are closely related to the tissue’s internal environment. The study aimed to investigate the morphological identification of TCs in the epididymis of adult yak and their role in the local microenvironment. In this study, transmission electron microscopy (TEM), scanning electron microscopy, immunofluorescence, qRT-PCR, and western blotting were used to analyze the cell morphology of TCs. The results showed that there are two types of TCs in the epididymal stroma of yak by TEM; one type is distributed around the capillaries with full cell bodies, longer TPs, and a large number of secretory vesicles; the other is distributed outside the basement membrane with irregularly long, striped, large nuclei and short telopodes (TPs). In addition, these TCs formed complex TC cell networks through TPs with epididymal interstitial capillaries and basal fibroblasts. TCs often appear near the capillaries and basement membrane by special staining. The surface markers of TCs  were positively expressed in the epididymal stroma and epithelium by immunohistochemistry, and immunofluorescence co-expression of vimentin + CD34 and CD117 + CD34 was observed on the surface of TCs. The trends in the mRNA and protein expression of TCs surface markers revealed expression was highest in the caput epididymis. In summary, this is first report of TCs in the epididymis of yak, and two phenotypes of TCs were observed. The existence and distribution characteristics of TCs in the epididymis of plateau yaks provide important clues for further study of the adaptation to reproductive function in the plateau. The unique morphological characteristics of TCs make them different from other mesenchymal cells. The TPs are in close contact with blood vessels, nerve bundles, and local immune system cells through organ matrix distribution, forming a network between tissues; this network was considered to be the structural basis for cell communication5. Furthermore, TCs may also establish unique spatial relationships with a variety of cells, including adjacent parenchymal cells and other cells in the interstitial compartment, and are considered to regulate the dynamic balance of the local microenvironment by contacting or releasing secretory vesicles between cells8. These secretory vesicles are considered to be “messengers” of substance exchange and signal transduction between TCs and other cells10, and are also an important reason why TCs are thought to be secretory cells. As early as a century ago, a special cell group in the muscular layer of the human intestinal tract was discovered by Cajal and named as “interstitial neurons”11. Telocytes were named by Popescu and Faussone-Pellegrini at the beginning of this century1. For many years, research on telocytes was based on imaging their ultrastructure under a transmission electron microscope, so transmission electron microscopy is considered the “gold standard” for research into TC morphology.Telocytes (TCs) are a newly discovered type of mesenchymal cells with unique morphological characteristics that have a long cytoplasmic extensions called telopodes (TPs). TPs are slender, long, and varied in number. Their shapes are mainly irregular ellipsoid, pear, and spindle; they are rich in mitochondria, the endoplasmic reticulum, and have a secretory function13. Furthermore, TCs were abundant in the mouse lung and rat kidney15. TCs were found in the fish brain16 and in poultry skin17. TCs have been discovered to be involved in many functional aspects in recent years, including cell regeneration18, inhibition of apoptosis19, inflammation repair20, cell communication21, angiogenesis23, and stem cell function19. In previous studies, CD34, CD117, and vimentin were widely considered effective markers of TCs26. The proteins are also widely used to locate and screen TCs. CD34 is a marker receptor found on the surface of mesenchymal stem cells; it is also a highly glycosylated type I transmembrane glycoprotein expressed on the surface of hematopoietic stem/progenitor cells of humans and other mammals29.TCs have been found in the human myocardium and gallbladder; CD34, c-kit (CD117), and vimentin were co-expression in TCs, and involved in stem cell differentiation, the coordination of new angiogenesis, and the regulation of paracrine function in the interstitial tissue30 and is considered one of the effective markers of TCs31. Vimentin, a conserved type III intermediate filament protein, is often found in fibroblasts, vascular endothelial cells, neutrophils, and macrophages, and is abundantly expressed in glomeruli, tubules, and renal interstitial cells32. Vimentin is a marker of mesenchymal phenotype and an important cytoskeletal protein. It is generally expressed only in mesenchymal cells and is closely related to the growth, invasion, and metastasis of tumor cells33. For a long time, studies of TCs have been based on some stem cell characteristics, with the stem cell surface markers such as CD34 and CD117 generally considered the marker proteins of TCs. Vimentin is a phenotypic marker of interstitial tissue, which is often used to locate TCs in the interstitial tissue.CD117 (C-kit) is a marker of stem cells/progenitor cells in the heart35. The internal environment and functions of epididymis affected by high altitude hypoxia environment, while the epididymis is an important place for sperm maturation, processing, and storage37. For example, the activity of the enzyme acrosome and its change in reactivity in hypoxic conditions damages sperm fertilization ability40. Therefore, our study aimed to determine the distribution location of TCs in the epididymis of yak and analyzed the ultrastructure of TCs, to provide new clues or information as to the function of TCs in plateau animals.Yak has a reputation as a ‘plateau boat’ and ‘omnipotent livestock’ in the Plateau pastoral areaTEM is the most effective method to identify TCs. TEM observation showed that the TCs in the epididymis of yak contained a large nucleus of indefinite shape; the most typical were ellipsoid, serrated, and pear-shaped. The nucleus, with obvious chromatin, was surrounded by a small amount of cytoplasm, rich in secretory vesicles and mitochondria. There were a large number of TPs composed of long cytoplasmic fragments Fig. A,B. MostThe SEM photographs were colored using Adobe Photoshop 2020 software. It was found that TCs had complete cell morphology with the presence of obvious cytoplasmic processes on TPs. TCs usually attached to the epithelium or connected to other cells through TPs, but exist alone in the epididymis stroma. Moreover, the vast interactions can be used to make a complex TPs network between adjacent epithelial cells, and cell secretions are attached to TPs FA–I.FigurThe morphological structure and the morphological model diagram of TCs in yak epididymis were proposed based on the results of TEM and SEM Figs.  and 6.FiThe toluidine blue staining results showed that a few TCs were distributed in the interstitium and more were distributed near the microvascular of the epididymis. However, they had different structures, adopting ellipsoid, spindle, pear, or other forms Fig. A–C. MercThe immunohistochemical results showed that thick epithelial cells, mesenchymal cells, and capillaries were observed in the epididymis of yak. CD34 was strongly expressed in the interstitium and distributed mainly in the interstitium and near the epithelium Fig. A–C. CompThe immunofluorescence results showed that vimentin was widely expressed in the epididymis of yak, including fibroblasts, perivascular muscle-like cells and vascular endothelial cells, with strong positive expression Fig. . These cp < 0.01). Although there was no significant difference in the expression trend in vimentin mRNA in caput and corpus, it was significantly higher than that in the cauda epididymis (p < 0.01). Similarly, CD117 mRNA expression in yak caput epididymis was also significantly higher than that in the corpus and cauda (p < 0.01)  Fig. . Western01) Fig. ; moreove41, fish brain16, and poultry skin, and TCs have common features: slender cytoplasmic extensions and a large nucleus. In addition, TCs were also found in the testis of rats42, rabbits43, and camels44. TCs found in our study have common morphological characteristics with previous studies. The large nucleus is one of the features of TCs, and serrated nuclei of TCs have so far been described only in camel testes, whereas the same was present in the serrated nuclei of the TCs in yak cauda.Homeostasis of the epididymal microenvironment guarantees male animal reproductive ability. As a type of interstitial cell, TCs play an important role in the epididymis immune microenvironment homeostasis and blood–epididymis barrier function. TCs have been found in many animal tissues, such as the human colon45. In this study, the TEM ultrastructure of TCs in different locations of the yak epididymis were identified. The TCs distributed around the capillaries or near the basement membrane had differences in morphology. The former has more full cell bodies and TPs are relatively long, whereas the latter had contrasting features. Some scholars have confirmed that TCs around the capillaries may be associated with angiogenesis and material exchange46. TCs near the epididymis basement membrane were closely connected with the peritubular myoid cells, which provide structural support for the epididymal duct, and may participate in the contraction of the epididymal duct, providing an impetus for the transport of sperm. The TEM analysis of the ultrastructure revealed that there were multitudinous secretory vesicles in the TPs of yak epididymis TCs; these were released to the surrounding environment of TCs in the form of exocytosis and were easily observed by TEM.TEM has been considered to be the most effective way to differentiate TCs from other mesenchymal and epithelial cells47, this feature is regarded as one of the most important conditions for distinguishing TCs from other interstitial cells in ultrastructure. We found TCs in the interstitium of the yak caput epididymis by SEM were mainly distributed in the interstitium and around the blood vessels. The differently sized TPs from TC cell bodies, as well as the network structure composed of dense TPs, can be observed by SEM, which is also one of the important characteristics of TCs.Our findings show that secretory vesicles also exist in TCs found in the human testis, myocardium, ovary, and other tissues. Considered the “messengers” of TCs that communicate with the outside worldIn this study, we explored multiple special staining methods and found that mercury–bromophenol blue stained TPs and the cytoplasmic processes dark blue. The cytoplasmic processes of TCs have the function of secreted proteins, and TCs in the yak epididymis of during the estrous season may be involved in the reproductive regulation of the epididymis through the secretion of related proteins by the cytoplasmic processes of TPs; thus, this suggests the need for further study of the seasonal variation characteristics of TCs.48. Because there was strong expression of vimentin in the stroma and epithelium of epididymis, the immunohistochemistry and double immunofluorescence co-localization were designed to determine the location of TCs. We found that the cells with double-positive expression of vimentin/CD34 and CD117/CD34 were similar to the TCs phenotype in the stroma and capillary of yak epididymis. These cells had a long cytoplasmic extension and oval nuclei, which were consistent with the basic characteristics of TCs. Similar results were found in testis of humans47, dove49, and Pelodiscus sinensis50. We found that the mRNA and protein expression of CD34, vimentin, and CD117 were relatively high in the yak caput epididymis. The caput epididymis plays an important role in sperm maturation and processing, especially in sperm concentration, maturation, and transport52. Compared with the corpus and cauda, the caput is more like a sperm “processing workshop”, suggesting that high expression of TCs markers in the epididymis caput may be related to sperm processing.Studies have shown that immunohistochemistry can be used as a basic method to localize TCs48, the TCs network of yak epididymis TCs may play an important role in the formation of yak blood–testicular barrier. Studies have found that TCs present in the epididymis of camels are positive for vascular endothelial growth factors53, indicating that TCs are probably involved in angiogenesis in the epididymis of the camel. TCs promote angiogenesis by secreting extracellular vesicles containing microRNA55. Angiogenesis is a process by which monolayer endothelial cells (ECs) control the permeability of blood cells through material exchange, and maintain homeostasis of the vascular environment and a series of physiological phenomena leading to the formation of new blood vessels56. Microvessels in the epididymis are considered to be the prerequisite for sperm maturation and transport57. Interestingly, we found that TPs of TCs were always extremely close to the blood vessel and extended to the vascular wall. Combined with TEM evidence, we speculated that TCs may be a material exchange pump that play an important role in the process of material and energy exchange between interstitial and nutrient vessels in the epididymis.Via double immunofluorescence staining, we also found that TCs were associated with dendritic cells, peritubular myoid cells, and lymphocytes through TPs. We believe that there is a specific network structure between TCs and the epithelium and stroma in the epididymis of yak, namely the TCs network. Following a previous discovery that the network structure of TCs in human testis may be related to the blood–testicular barrier59, such as injury repair61, vascular regeneration62, and cell communication63. However, there are few studies of TCs in animal reproduction. Studies have found that the secretory vesicles of TCs in camel testis are affected by seasonal changes, with more secretion in spring and less secretion in summer44. There is some relationship between TCs secretion vesicles and camel estrus. However, there is insufficient evidence to prove TCs are involved with the regulation of animal estrus. Some researchers believe that TCs may indirectly affect the secretion and release of androgen by establishing intercellular connections with other interstitial cells to regulate the reproductive activities of male animals48. Furthermore, studies reported that TCs express progesterone and estrogen receptors in the female gonadal axis66. The emergence of such studies is constantly drawing TCs into the field of reproductive study. Our study revealed the morphological structure and distribution location of TCs in yak reproductive organs and provided a reference for the study of TCs in animal reproduction in a hypoxic plateau environment.At present, more function of TCs are emergingThe epididymal tissue of adult healthy yak  was collected from designated slaughterhouses from July to August in Xining City, Qinghai Province  China. Based on their anatomical characteristics, epididymis samples were divided into three parts: caput, corpus, and cauda. A portion of each sample was quickly frozen in liquid nitrogen, transported to the laboratory and then stored at −80°C for RNA and protein extraction; the remaining samples were stored in 4% paraformaldehyde and 2.5% glutaraldehyde separately for histological and ultrastructural study. All experimental animals were approved by the Animal Care and Use Committee of the Veterinary College of Gansu Agricultural University (Ratification number: GSAU-Eth-VMC-2021-010), and all methods were performed in accordance with the relevant guidelines and regulations.All experimental antibodies were purchased from commercial suppliers. Rabbit polyclonal antibody CD34 (bs-8996R), vimentin (bs-8533R), and CD117 (bs-1005R) were purchased from Beijing BIOSS Antibodies Co., Ltd, China. Goat anti-rabbit IgG H&L  were provided by Abcam,Cambridge, UK. The DAB color reagent kit (PA110) was provided by Beijing TIANGEN Biotechnology Co., Ltd. The immunohistochemical staining kit (SP-0023) used was produced by ZYMED USA, Beijing BIOSS Biotechnology Co., Ltd. ECL Plus ultrasensitive luminescent solution (PE0010) was purchased from Solebao Biotechnology Co., Ltd.Preparation of ordinary samples: Epididymal tissue samples (0.5 × 0.5 × 0.5 cm) were fixed with 4% paraformaldehyde solution and rinsed in running water for 24 h before gradient ethanol dehydration. Subsequently, samples were made transparent with xylene, embedded using an Epon 812 paraffin embedding machine, and 4-μm-thick serial sections were cut. Adjacent slices were used for toluidine blue staining, mercury–bromophenol blue staining, immunohistochemistry and immunofluorescence staining, respectively.SEM sample preparation: The epididymal tissue of yak was cut into 0.2 cm × 0.2 cm × 0.2 cm pieces and fixed with 2.5% glutaraldehyde for 2 days. The tissue was washed four times with 0.1 mol/L phosphate buffer; each wash was 15 min. The samples were treated with 1% OsO4 for 1 h and washed with double-distilled water six times (10 min each wash). Then, the tissue was treated with 2% tannic acid for 30 min and washed with double-distilled water six times (each wash 10 min), and then subjected to gradient ethanol dehydration  and then soaked in isoamyl acetate for 30 min. Tissues were dried by critical point drying, and then the samples were sprayed with gold and observed using a scanning electron microscope.TEM sample preparation: The epididymal tissue of yak fixed in 2.5% glutaraldehyde was cut into small pieces (0.2 cm × 0.2 cm × 0.2 cm) and fixed in 2% osmium tetraoxide at 4°C for 3 h. The pieces were dehydrated with a gradient acetone series  and then embedded in epoxy resin. Ultrathin sections were prepared and affixed to the copper mesh, stained with uranium acetate and lead citrate, and then examined using a JEM-100CX electron microscope (Japan NEC).The epididymal tissues were embedded in paraffin and cut into 4-µm-thick sections. Paraffin sections were dewaxed and dehydrated, repaired with microwave oven antigen retrieval, blocked with 3% H2O2 solution for 10 min, and incubated with goat serum albumin for 15 min. Subsequently, 50 µL rabbit polyclonal antibody  diluted to 1:300 was added to each slide; the negative control consisted of 0.01 mol/L PBS instead of the first antibody. The slides were incubated at 37 °C for 4 h, washed three times with phosphate buffer solution (PBS) (each wash 5 min) and then 50 µL of biotin-labeled goat anti-rabbit IgG working solution was added and the sections were incubated at 37 °C for 15 min and washed three times with PBS (each wash 5 min). Horseradish enzyme-labeled streptavidin solution was added and washed with PBS three times . The DAB color developing solution was added for 5–20 min. Hematoxylin counterstaining was performed for 5 min; then, sections were dehydrated by an alcohol gradient, made transparent with xylene, and sealed with neutral gum. The sections were observed under a microscope.Immunofluorescence staining was performed with the primary antibody; sections were incubated at 37°C for 4 h and rinsed with PBS three times. Subsequent steps were completed in a dark room. Anti-Rabbit IgG H&L AF488 or AF594 (dilution ratio 1:1000) was added, incubated at 37°C for 1 h, and washed five times with PBS (each wash 5 min). Then, the second antibody was added and the sections were incubated at 37°C for 4 h, washed five times in PBS (each wash 5 min). Rabbit Anti-PHD2/AF647 (dilution ratio 1:1000) was added dropwise and incubated at 37°C for 1.5 h. After washing with PBS, DAPI was added dropwise and incubated in a dark room for 10 min. After further washing with PBS, the patch was sealed with a capping agent and the sections were observed under a laser confocal microscope. The negative control consisted of 0.01 mol/L PBS instead of the first antibody. The remaining conditions and steps were the same.www.ncbi.nlm.nih.gov), and the primer information is shown in Table The caput, corpus, and cauda tissues of yak epididymis stored at − 80 °C were removed from storage, and 0.1 g was weighed and placed into a mortar. Liquid nitrogen was added to the grind, and 1 mL Transzol was added to the shock treatment. Then 0.2 mL of chloroform was used to extract RNA and confirm its purity. cDNA was synthesized by RNA reverse transcription, and stored in a refrigerator at − 80 °C for further use. Primer Premier 5.0 software was used  was used to design primers; the primer sequence was obtained with reference to the NCBI database , and all proteins were diluted to the same concentration. Protein samples (25 μg) were separated by SDS–polyacrylamide gel electrophoresis (SDS-PAGE) using a 5% stacking gel and 12% separating gel. After electrophoresis, the separation gel was cut according to the size of the target protein and referred to the Marker, and the cut target bands were then wet-transferred to the support membrane, and the membrane was incubated with primary antibodies (1:800) at 4 °C overnight and washed with Tris-buffered saline + Tween 20 (TBST). Horseradish peroxidase-labeled goat anti-rabbit IgG was used as the secondary antibody and the incubation was performed for 2 h at 37 °C in TBST buffer for 10 min. The polyvinylidene fluoride membrane was then subjected to chemiluminescence detection. Chemiluminescent substrate solutions A and B were mixed at a ratio of 1:1, and the reaction proceeded at 25 °C. The transfer membrane was photographed for analysis, with β-actin used as the internal reference.Western blotting data were quantified by ImageJ software . The qRT-PCR data were analyzed by the 2 − ΔΔCT method; the obtained results were subjected to the dominance test by SPSS 17.0 statistical software, and the histogram was plotted by GraphPad 9.0 software.The study is reported in accordance with ARRIVE guidelines. And all experimental animals were approved by the Animal Care and Use Committee of the Veterinary College of Gansu Agricultural University (Ratification number: GSAU-Eth-VMC-2020-016w).Supplementary Information 1.Supplementary Information 2.


A relationship between microvascular disorders and sensorineural hearing loss (SNHL) has been widely proposed. The vascular hypothesis, theorized for the onset of sudden SNHL (SSNHL), is among the most acknowledged: a localized acute cochlear damage, of ischemic or haemorrhagic nature, could be considered a causative factor of SSNHL. The aim of this review is to assess (i) the effect on hearing in patients affected by blood coagulation disorders (prothrombotic or haemorrhagic) and (ii) the possible etiopathogenetic mechanisms of the related hearing loss. A PRISMA-compliant review was performed. Medline, Embase, and Cinahl databases were searched from inception to 31 January 2023, and a total of 14 studies have been included in the review. The available data suggest that it is possible to consider clotting disorders as a potential condition at risk for sensorineural hearing loss; in particular, coagulation tests and eventually the assessment of genetic and acquired prothrombotic factors should be recommended in patients with SSNHL. Also, an audiological evaluation should be recommended for patients with blood coagulation disorders presenting cochlear symptoms, especially in those suffering from clotting diseases. The vascularization of the inner ear is provided by a terminal capillary bed originating from the labyrinthine artery . Given tThe aim of this review is to assess (i) the effect on hearing in patients affected by blood coagulation disorders (both clotting and bleeding disorders) and (ii) the possible etiopathogenetic mechanisms of the related hearing loss.The PubMed, Embase, and Cinahl databases were searched from inception to 31 January 2023. The research was performed according to Preferred Reporting Items for Systemic reviews and Meta-Analyses (PRISMA) criteria ; it was Initially, the total number of papers identified was 76; other papers (6) were also identified from references in the published literature when all authors agreed about the reliability and importance of these manuscripts, for 82 papers in total. A total of 19 papers were selected by reading titles and abstracts. After reading the full texts, 14 papers were suitable for this review according to all authors.A total of 14 papers were included in this study; among these, 9 were case reports. Clotting disorders were investigated in 11 studies and bleeding disorders in 3 papers. A summary of the included studies is presented in p = 0.001) [p = 0.02) [p = 0.0001) [The V Leiden G1691A mutation was found to be significantly more frequent in a group of 100 patients with SSNHL than in 200 healthy controls (= 0.001) , and in  = 0.02) . Further 0.0001) . Differe 0.0001) . Finally 0.0001) .Three case reports were found in the literature. Lovato et al.  reportedp = 0.001) [p = 0.0001) [p < 0.0001 and p = 0.0091, respectively). This finding was not confirmed by other studies: neither in a group of 56 patients with SSNHL compared to 95 control healthy subjects [The prothrombin G20210A mutation was found to be more frequent in 100 patients with SSNHL than in controls , with statistical significance (= 0.001) . Further 0.0001) . In two  0.0001)  and a gr 0.0001) , respectsubjects  nor in asubjects .A significant relation between SSNHL and abnormal levels of protein S was not found, neither in a group of 48 patients with SSNHL compared to 86 healthy controls , nor in According to the literature, there is only one case reporting  on a 34-No significant association between SSNHL and abnormal levels of protein C was found in a group of 48 patients with SSNHL compared to 86 healthy subjects , or in 3No significant correlation between SSNHL and abnormal levels of activated protein C resistance (APCR) was found in a group of 48 patients with SSNHL compared to 86 healthy controls , or in 3In the case reported by Crassard et al., an increased APCR was described in a 42-year-old woman with a heterozygous mutation of factor V presenting with cerebral sinus venous thrombosis and unilateral moderate SSNHL . CompletIn a cohort of 14 patients with SSNHL compared to 50 healthy subjects , ZajtchuIn a case report, a 48-year-old woman presenting with sequential bilateral SSNHL was affected by antithrombin III deficiency; no hearing threshold improvement was observed after corticosteroid therapy .In a cohort of 14 patients affected by SSNHL compared to 50 healthy subjects , no signIn the available literature, there is only one case reported so far. Kashiwazaki et al.  describeSchlegelberger et al.  describeOnly one case report described bilateral hearing loss in a 5-year-old boy presenting acute ITP purpura and bilateral hearing loss due to bilateral spontaneous hemotympanum . NonetheHearing loss represents a possible extra-haematological manifestation in patients affected by blood coagulation disorders. Due to the different types of clotting and bleeding conditions, non-haematological complications, including hearing loss, may develop with variable occurrence and different severity. This review aims to evaluate the possible relationship between blood coagulation disorders, of ischemic or haemorrhagic nature, and hearing loss. Among the papers identified, the majority are represented by case reports. This fact could suggest that (i) the occurrence of hearing loss is uncommon in patients affected by blood coagulation disorders, and that (ii) a pathogenetic correlation between hypercoagulative and hypocoagulative states and hearing impairment is difficult to prove.Conditions characterized by blood hypercoagulability may also increase the risk of thromboembolic events in the inner ear. In fact, a significant association between SSNHL and the prothrombin G2021, the platelet GlyIIIaA1/A2, and factor V Leiden G1691A mutations has been reported .Among the proposed pathogenic mechanisms of SSNHL, the vascular hypothesis is the most widely accepted . The anoConsistent with the results of the present review, the factor V Leiden and the prothrombin G20210A mutations, which represent the most common and the second-most common inherited thrombophilia, respectively , were foWhen a cerebral sinus venous thrombosis is diagnosed, such as in the case reports by Crassard et al.  and GattAccording to the present review, only three case reports met the inclusion criteria when considering bleeding disorders. This fact firstly suggests that conditions of hypocoagulability seem to be not related to hearing loss. Nonetheless, bleeding diathesis could foster haemorrhages in unusual sites. Audiological examination should be considered in the diagnostic workup of these patients, since even a simple sneeze or cough may be responsible for intratympanic bleeding in the case of sudden and rapidly increased middle ear pressure . FurtherEventually, inner ear haemorrhage has been linked to SSNHL ,9. As foThe literature data suggest that hearing threshold recovery in cases of SSNHL due to ischemic and/or haemorrhagic events is very poor, especially when the loss of function is bilateral and/or profound . MoreoveA major drawback of this study is the lack of reliable and significant data, as almost half of the included studies are case reports. However, this fact may reflect (i) the rarity of hearing loss occurrence in patients suffering from blood coagulation diseases, and that (ii) clotting and bleeding disorders have been poorly investigated as causes of hearing loss. Furthermore, the lack of evidence could also be due to the current difficulties in investigating inner ear disorders, since there is an absence of proper diagnostic tools for evaluating the status of cochlear cells, or the inner ear’s microcirculation, despite the advances in diagnostic techniques over recent decades.According to the available data, clotting diseases could be considered a potential condition with a risk of hearing loss. For this reason, even if a routine comprehensive haematological screening could be too expensive to be performed in all patients affected by hearing loss, audiologists should at least investigate patients presenting with SSNHL through coagulation tests and eventually assess them for genetic and acquired prothrombotic factors (such as the factor V Leiden and prothrombin mutations). This could allow the identification of those at high risk of thrombotic events. At the same time, haematologists should pay attention to audiological symptoms, and a hearing assessment should be recommended for patients with clotting disorders.To date, a specific and standardized approach for investigating the pathogenetic mechanisms occurring in the inner ear, and particularly to evaluate the onset of hearing loss in patients affected by hypercoagulative and hypocoagulative states, is not available yet. In fact, it is still difficult to investigate the cochlear cells’ status and the condition of the inner ear’s microcirculation with the available standard diagnostic approaches.However, considering the advancements over the last decades, modern magnetic resonance imaging (MRI) cannot just rule out retrocochlear pathologies, but can also provide a more detailed study of the inner ear compartments. The advent of 3-Tesla MRI has provided new imaging support for the morphological study of the inner ear. New MRI protocols, such as the three-dimensional fluid-attenuated inversion recovery (3D-FLAIR)  and threOn the contrary, specific ischemic events within the inner ear seem to be more difficult to detect, especially if temporary, by the available radiologic techniques. Nonetheless, new insights could arise from the use of higher magnetic fields , or by performing earlier MRI sequences, within 24–48 h, from the onset of hearing loss.Implementing new diagnostic tools could improve diagnostic accuracy, allowing not just the detection of labyrinthine abnormalities but also, possibly, the identification of damaged blood–labyrinth barrier, thus providing important advantages in terms of prognostic information. It is likely that, in the near future, the use of new MRI protocols could provide more reliable data about the possible etiopathogenetic mechanisms of inner ear disorders.


BackgroundThere are numerous quality-of-life (QoL) assessment tools available; however, only a few are designed specifically for children with chronic conditions. Among these assessment tools are the Hearing Environments and Reflection on QoL questionnaires for children  developed by Washington University. Unfortunately, there are no other tools that assess hearing loss, and none of them are in Arabic. This paper aims to adapt the HEAR-QL to Arabic and provide an accessible method of measuring the QoL of children with hearing loss in our Arabic-speaking populations.MethodologyAn independent medical translator translated the HEAR-QL26 and HEAR-QL28 into Arabic. The translations were then examined by two bilingual, native Arabic-speaking otolaryngologists who modified the inadequate questions. Back-translation of the Arabic version into English was subsequently performed by an independent translator. Intra-rater reliability was tested for each of HEAR-QL26 and HEAR-QL28 using 10 participants for each survey, where the participants answered the surveys twice with a period of two weeks between them. A pilot study was conducted which had a total of 40 participants divided equally between the two surveys where each group had an equal number of hearing participants and participants with hearing loss.ResultsBoth HEAR-QL26 and HEAR-QL28 were validated with an overall intra-rater reliability of 88.85% and 87.86% respectively. In the pilot study, the HEAR-QL26 participants with normal hearing scored a median of 2437.5, while the participants with hearing loss scored a median of 1837.5 (p = 0.001). Moreover, HEAR-QL28 participants had a median score of 2725 among participants with normal hearing and 1725 for participants with hearing loss (p = 0.001).ConclusionHEAR-QL is a well-established QoL in children with hearing loss. The validated Arabic adaptation can now be used to measure deafness in Arabic-speaking children. Hearing loss occurs when there is a disturbance in the usual functioning of any part of the ear. This includes the following: the outer ear, middle ear, inner ear, acoustic nerve, and auditory system . The WorMany quality-of-life assessment tools are available, such as the Pediatric Quality of Life (PedsQL); however, few are specific to children with chronic conditions. Among these assessment tools are the Hearing Environments And Reflection on Quality of Life Measurement for Children surveys  developed by Washington University. These surveys assess the quality of life among children with hearing loss by examining many factors, such as environments, activities, and feelings using the HEAR-QL26 and hearing situations, social interactions, school difficulties, and feelings using the HEAR-QL28. HEAR-QL is reportedly more sensitive and effective than PedsQL . UnfortuDevelopment of the Arabic versions of HEAR-QLAfter obtaining permission from Washington University and the original authors of the English version of HEAR-QL, an independent medical translator translated the HEAR-QL26 and HEAR-QL28 into Arabic. The translations were then examined by two bilingual native Arabic-speaking otolaryngologists who modified the inadequate questions. Back-translation of the Arabic version into English was subsequently performed by an independent translator who was not aware of the English versions of the HEAR-QL. The source of measurement used in this study is described in a paper by Umansky et al. (2011) [Validity of the Arabic questionnaireThe study was approved by the institutional ethics review board. Written and informed consent was obtained from all participants prior to enrollment in this study.In this study, two groups were established; Group A consisted of 10 children between the ages of 7-12 years, while Group B consisted of 10 children between the ages of 13-18 years. The HEAR-QL26 was given to Group A, while the HEAR-QL28 was given to Group B. All the children involved in this study had normal hearing, had Arabic as their first language, and were not suffering from any cognitive impairment. Pilot studyThe pilot study included 40 children, half of whom participated in the HEAR-QL26 and the other 20 in the HEAR-QL28 survey. Among the 20 participants who completed the HEAR-QL26 included 10 participants with normal hearing and 10 participants with hearing loss. The HEAR-QL28 participants were also divided into groups of 10 participants with normal hearing and 10 participants with hearing loss. A comparison was also made between the participants with normal hearing and hearing loss in both surveys.Statistical analysisBoth the HEAR-QL26 and HEAR-QL28 use a brief scoring system comprising a 5-point scale. The options were: almost always (0), often (1), sometimes (2), almost never (3), and never (4). The scores for the options were converted to 0-100 scores distributed as follows: 0=0, 1=25, 2=50, 3=75, and 4=100. With respect to hearing, lower scores indicated a poorer quality of life, while higher scores indicated a greater quality of life.HEAR-QL26 and HEAR-QL28A total of 20 participants with normal hearing, 10 for each survey, were asked to join this study and answer the translated HEAR-QL26 and HEAR-QL28 twice separated by a period of two weeks to determine the validity of the translated questionnaire.The HEAR-QL26 participants included 10 children between the ages of 7 and 12. The median score of the participants was 2462.5 (94.7%) in the first round, whereas, they scored a median of 2575 (99.04%) in the second round.Another 10 participants between the ages of 13 and 18 answered the HEAR-QL28 translated survey. On the first attempt, the participants had a median score of 2687.5 ; upon taking the survey two weeks later, they showed a median score of 2737.5 (97.8%).Intra-rater reliabilityThe HEAR-QL26 survey was validated with overall intra-rater reliability of 88.85%, while the HEAR-QL28 survey was validated with 87.86% overall intra-rater reliability. Pilot studyThe pilot study included 40 children, half of which took the HEAR-QL26 and the other half took the HEAR-QL28 survey. Among the 20 participants that took the HEAR-QL26, 10 were participants with normal hearing and 10 were participants with hearing loss, both with a median age of 10 years. The participants with normal hearing scored a median of 2437.5 (93.75%), while the participants with hearing loss scored a median of 1837.5 (70.675%) (p = 0.001)  for the participants with normal hearing and 1725 (61.61%) for the participants with hearing loss (p = 0.001). Tables % for theTranslating the surveys HEAR-QL26 and HEAR-QL28 from English to Arabic was of great importance since it has provided a validated tool to assess the quality of life in Arabic-speaking children with hearing loss. Each survey scored an intra-rater reliability of over 85%; using the Arabic version of the survey could enable further research into the quality of life of Arabic-speaking children with hearing loss. Hearing loss clearly puts a person at a disadvantage, and even if it is obvious that this places children with hearing impairment in vulnerable positions, the actual impact on quality of life still requires to be defined . One of Hearing impairment has significant impacts on those who are affected, regardless of their age or degree of disability. Owing to a lack of early auditory stimulation and spoken communication, children and youth who were born with hearing impairment or acquired hearing impairment at a younger age are at risk of delayed speech, language, cognitive, and social development . InitialMany studies have demonstrated that children with hearing loss had lower scores on quality-of-life questionnaires compared to their peers with normal hearing ,20. SimiThere is a significant relationship between hearing rehabilitation and quality of life; specifically, the students who received hearing rehabilitation reported a higher quality of life than those who never received hearing rehabilitation. However, the majority of children with hearing impairment do not wear hearing aid devices owing to economic and stigmatic reasons, especially in middle- and low-income countries . For thaHEAR-QL is a well-recognized tool to measure the quality of life in children with hearing loss, and in this Arabic adaptation of the surveys, we provide a validated tool measuring the quality of life in children with hearing loss who speak Arabic as a native language.


Dear Editor,12Mucormycosis has been considered an uncommon, life-threatening infection by filamentous fungi living in the soil and vegetable or animal-decomposing matter, causing the infection through superficial lesions and spore inhalation or ingestion, mainly in people with diabetes, malignancy, hematological diseases, or immunosuppression condition.2 about gastric mucormycosis incidentally diagnosed in the autopsy of an Indian man who died of septicemia one week after a road traffic accident. Gastrointestinal (GI) mucormycosis is estimated to occur in up to 13% of the invasive infections, involving the stomach in 58% of the cases, or the small and large intestines. However, only one-fourth of these cases have been clinically diagnosed.2 The authors emphasized the incidental diagnosis of this life-threatening mycosis by endoscopy or autopsy, which has increasing in frequency in recent decades.2 The mortality rate of GI mucormycosis is up to 78% of cases, with perforated ulcers and peritonitis being the leading causes of death.2 This letter aims to present a review of this issue, including articles from 2020 to 2023.We read the report by Bhowmik et al.1 reported a 22-year-old Indian woman who had acute pancreatitis two months after the normal delivery and evolved with thrombosis of the left cavernous venous sinus, diabetic ketoacidosis, and GI bleeding due to a large gastric perforation. Gastric samples revealed broad aseptate and foldable fungal hyphae and angioinvasion. She received intensive care support and underwent a laparotomy with subtotal gastrectomy, feeding jejunostomy, and ileostomy, in addition to amphotericin B and oral posaconazole. Notwithstanding, her clinical condition worsened, and she succumbed after six weeks. The authors emphasized the association of mucormycosis with diabetic ketoacidosis.1 Khsiba et al.7 reported fatal invasive gastric mucormycosis in a 61‐year‐old diabetic Tunisian woman and a previously healthy 59‐year‐old foreign man living in Tunisia. The woman had a one-week history of vomiting after 4 months of inhaled corticoids for cough, and the upper GI endoscopy with biopsy revealed invasive mucormycosis by Rhisopus arrhizus. The patient had to stop conventional amphotericin B due to a renal function impairment; she also underwent total gastrectomy 2 months after the diagnosis but died 10 days later.7 The male patient presented with gastric pain, vomiting, worsened general state, and fever; the upper GI endoscopy showed a bleeding gastric ulcer, and the biopsy study detected typical zygomycetes hyphae. He did not undergo specific treatment for mucormycosis, and the outcome included septic shock and hemophagocytic syndrome, dying after eight days of admission.7 The authors stressed the mortality being up to 85% without early diagnosis and therapy.7 Noor et al.10 reported a 21-year-old man presenting gastritis-like symptoms, who was recently treated for hemophagocytic lymphohistiocytosis, and a fungal sinusitis. The upper GI endoscopy revealed an extensive gastric involvement by mucormycosis, and the patient underwent antifungal drugs and resection of the necrotic gastric tissue. In this case, it was worthy of note the young age, the lack of risk factors such as diabetes or immunosuppression, and the development of hemophagocytic lymphohistiocytosis. The authors highlighted the role of early diagnosis and prompt treatment on outcome.10 Yuvaraj et al.12 described a 53-year-old man with diabetes mellitus and alcoholism who had acute abdominal pain and hematemesis. The imaging studies showed a gastric wall thickening and exophytic ulceration involving the greater curvature and the splenic hilum, and evidence of splenic infarction. Biopsy studies of the mass revealed broad aseptate branched fungal hyphae consistent with the diagnosis of gastric mucormycosis, and amphotericin-B was administered; however, the gastrectomy and splenectomy procedures were not performed because of the patient’s clinical condition, and he irreversibly evolved to death.12 The authors highlighted the high index of suspicion and physicians’ awareness needed for early diagnosis and treatment of mucormycosis, mainly in immunocompromised patients.12 Recent articles on COVID-19-associated mucormycosis (CAM) have been published.9 It is estimated a higher prevalence of CAM than the reported cases because of the lack of population-based research. Thus, CAM cases may be higher than the described ones.4 Patients with COVID-19 treated with intensive care support are prone to nosocomial and ventilator-associated infections.13Gurjar et al.3 reported a 35-year-old man with fever, vomiting, delirium, dyspnea, and cough, in addition to melena. Pulmonary thromboembolism and bilateral ground glass opacities were revealed by chest imaging study. The upper GI endoscopy showed multiple gastric black ulcers. Histopathological examination of the gastric biopsy revealed a broad, classical aseptate, ribbon-like, and foldable pattern of the mucormycosis fungal hyphae. Under amphotericin B therapy, he presented mental confusion, paraparesis, and left upper limb weakness. Contrasted computed tomography showed ring-enhancing brain lesions that were considered as a manifestation of the yeast infection. Due to clinical suspicion of recent infection by SARS-CoV-2, the IgM test was positive. Treatment of this patient included posaconazole evolving to an asymptomatic clinical status and complete vanishing of the CNS lesions.3 Worthy of note is the disseminated mucormycosis in the absence of any apparent risk factor, except for COVID-19 infection that has been associated with prothrombotic conditions.3 Malakar et al.8 described an 82-year-old man with GI bleeding for five days who utilized prednisolone for 21 days to treat moderate COVID-19 infection 2 months ago. The upper GI endoscopy detected a gastric ulcer extending from the gastroesophageal junction, and biopsy studies showed fungal hyphae consistent with gastric mucormycosis. For 13 days, he used pantoprazole and amphotericin B, which was changed by posaconazole due to worsening renal function and continued for three months till the ulcer was healed.8 The authors emphasized a rare cause of GI bleeding in a patient who had COVID-19, and the extensive mucormycosis successfully treated by anti-fungal therapy without surgery.8 Monte et al.9 described an 86-year-old man presenting with acute diarrhea, cough, dyspnea, and fever five days before, and a throat swab confirmed COVID-19.9 With acute respiratory failure and hemodynamic instability, he had intensive care support and underwent a schedule of ceftriaxone, azithromycin, oseltamivir, and hydrocortisone. Five days later, he had melena, and the upper GI endoscopy showed two giant gastric ulcers in greater and lesser curvatures; a histopathological study confirmed mucormycosis, but the patient died one week following admission and before the established diagnosis. The authors cited preemptive therapy in a patient with features suggesting mucormycosis.9 Dam et al.4 reviewed the pathogenesis, causal agents, determinants, distributions, manifestations, virulence factors, case reports, diagnosis, and treatment related to the increasing trend of mucormycosis in several countries and the COVID-19 co-infections. The study comprised 388 cases and showed 46.7% of global mortality; 56.8% of the cases were associated with uncontrolled diabetes and 10.2% with trauma, the majority of cases and the higher mortality rate were observed in North India (82.7%).4 GI infection was uncommon and with nonspecific symptoms, affecting the large intestine (∼43.2%), stomach (∼33%) often in adults, and small intestine (∼28.4%), mainly in children. The mortality was 96% in disseminated, 85% in GI, and 76% in pulmonary infections.4 The authors stressed the risk of improper use of antifungal drugs for the mucormycosis surge in the present pandemic, which might contribute to antifungal resistance over time.4 Didehdar et al.5 reviewed 87 reports of GI mucormycosis from 2015 to November 2021, including 70 adults and ten neonatal patients, the majority of cases (57.5%) from Asia. The mortality rate of neonatal patients was 70%, the other cases had a mortality rate of 44%; corticosteroid use and diabetes were the main risk factors, 11% were immunocompetent, and four of the adults presented with specific positivity tests of COVID-19 infection.5 Abdominal pain, fever, and perforation were common; 40% of the neonatal cases presented vomiting. Surgery plus antimycotic agent (61%), antimycotic therapy alone (28%), and surgery alone (11%) were the therapeutic approaches. All neonatal patients underwent a surgical procedure; posaconazole (30%) and isavuconazole (11%) effectively treated these patients.5 The authors commented on low immunity during the COVID-19 pandemic favoring the high prevalence of mucormycosis in India and the difficulties of early diagnosis and treatment.5 Divakar6 reviewed data about mucormycosis in general and the cases associated with the two waves of COVID-19 infections in India.6 The estimated mortality rate of mucormycosis (50%) may be over 90% if untreated; Rhizopus arrhizus was the most common agent of human mucormycosis described in Indian patients, followed by Apophysomyces variabilis, R. microsporus, and R. homothallicus.6 Mucormycosis among COVID-19 patients, including the mortality rate, are increasing in India and some of the neighboring countries such as Bangladesh, Nepal, and Pakistan.6 Because of species-specific differences, there are therapeutic challenges in India, with only three potentially efficient drugs . The authors cited accurate species identification as crucial for the correct diagnosis of mucormycosis, and for developing species-specific antifungal drugs.6Chauhan et al.In conclusion, although considered a rare entity, GI mucormycosis must be a plausible hypothesis if an atypical gastric ulcer is detected in people with COVID-19.


Euglena gracilis were studied in this study after 7 days of TCS treatment. A distinct inhibition ratio for the photosynthetic pigment content in E. gracilis was observed from 2.64% to 37.42% at 0.3–1.2 mg/L, with TCS inhibiting photosynthesis and growth of the algae by up to 38.62%. Superoxide dismutase and glutathione reductase significantly changed after exposure to TCS, compared to the control, indicating that the cellular antioxidant defense responses were induced. Based on transcriptomics, the differentially expressed genes were mainly enriched in biological processes involved in metabolism pathways and microbial metabolism in diverse environments. Integrating transcriptomics and biochemical indicators found that changed reactive oxygen species and antioxidant enzyme activities stimulating algal cell damage and the inhibition of metabolic pathways controlled by the down-regulation of differentially expressed genes were the main toxic mechanisms of TCS exposure to E. gracilis. These findings establish the groundwork for future research into the molecular toxicity to microalgae induced by aquatic pollutants, as well as provide fundamental data and recommendations for TCS ecological risk assessment.Triclosan (TCS), a commonly used antibacterial preservative, has been demonstrated to have high toxicological potential and adversely affects the water bodies. Since algae are one of the most significant primary producers on the planet, understanding the toxicological processes of TCS is critical for determining its risk in aquatic ecosystems and managing the water environment. The physiological and transcriptome changes in  Water environmental management issues resulting from the increased wastewater generation associated with antimicrobial agents are a major challenge for countries . TriclosKnow = 4.8) and long half-life [50) values of TCS for fish and microalgae. For fish, the LC50–96 h was 600.0 μg/L for Poecilia vivipara and 1700.0 μg/L for Oryzias latipes [50) of 27.1 and 93 μg/L for Pseudokirchneriella subcapitata and Dunaliella tertiolecta, respectively, while freshwater algae are more sensitive than marine algae and bacteria [P. subcapitata) at TCS concentrations ranging from 20.0 to 4000.0 μg/L report that this biocide promotes a reduction in the chlorophyll concentration [As a typical hydrophobic organic compound, TCS exhibits further environmental persistence, based on its high octanol water partition coefficient . Checcucci culture medium was used to cultivate the microalgae at 25 ± 1 °C under a 12 h/12 h light/dark cycle, with an illumination intensity of 3000 lux and three replicates [TCS (purity > 97%) was purchased from Aladdin Reagent Co., Ltd. . plicates . The cong for 15 min. Then, 5 mL of phosphate buffer solution  was used to resuspend the algal cells while ensuring that the original microalgal density was in the exponential growth phase at approximately 1 × 105 cells/mL. Briefly, to calculate EC50, E. gracilis was exposed to different concentrations of TCS , and blank and acetone solvent control groups (0.15%) were performed. The cell density was measured every 24 h at a wavelength of 680 nm, which had a linear correlation with the cell number, according to our previous study using Multiscan spectroscopy , allowing the establishment of a 96 h growth curve for E. gracilis [The pretreatment of algae was conducted as per our previous research . The alggracilis . To furt7 cells/mL) from the TCS-E and TCS-H treatments and the acetone solvent control group were centrifuged at 3500× g for 15 min in a 1.5 mL centrifuge tube. Subsequently, 1 mL of room temperature 2.5% glutaraldehyde  was added to the pellet. The cells were fixed at room temperature for 2 h in the dark and then stored at 4 °C prior to analysis. Ultrastructure images were taken by TEM .After 96 h of exposure, 15 mL of algal solution  was added to samples and mixed well, and the suspension was then placed at room temperature in the dark for 24 h. After extracting the pigments, the mixture was centrifuged again at 3500× g for 15 min, and 80% acetone was used for the control group. The collected supernatant was subjected to Multiscan spectrum analysis at wavelengths of 663, 645, and 470 nm. Chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoid (CAR) contents and the inhibition rate were calculated according to the following equations [After 96 h of exposure to TCS, 1 mL of microalgal suspension from each treatment group was centrifuged at 3500× quations :(1)Chl aA663, A645, and A470 are the fluorescence values at wavelengths of 663, 645, and 470 nm measured by the microplate reader .After 96 h of exposure to TCS, algal cells were centrifuged and rinsed three times with phosphate buffer saline (PBS). The activities of superoxide dismutase , glutathione , and reactive oxygen species  were determined using commercial kits  for the estimation of oxidative stress . The pro6 cells) via TRIzol extraction . A NanoDrop instrument was used to determine the RNA concentration, while the RNA integrity was checked by automated electrophoresis on an Agilent 4150 Tapestation system. After meeting the requirements of sequencing and library construction, the library was constructed.After 96 h of exposure to TCS-E and TCS-H, total RNA was extracted from 10 mL of algal cultures (>5 × 10ftp://ftp.ncbi.nlm.nih.gov/blast/db (accessed on 15 August 2022)) (NR), Pfam (http://pfam.xfam.org/ (accessed on 15 August 2022)), Gene Ontology (GO), Kyoto Encyclopedia of Gene Genotype (KEGG), and SwissProt (http://ftp.ebi.ac.uk/pub/databases/swissprot (accessed on 15 August 2022)) databases. Subsequently, the unigenes were annotated to the corresponding classification by NCBI BLAST 2.6.0 + software [Clean reads were assembled using Trinity software v2.13.2 , and unigenes were generated by TGICL purification . The asssoftware  to obtai2foldchange| ≥ 1, p value ≤ 0.05). According to the differential gene detection, this experiment classified and enriched the gene ontology (GO) function and analyzed the KEGG biological pathways and enrichment of the obtained DEGs.The FPKM (fragments per kilobase of exon model per million mapped fragments) value of each gene in each sample was calculated by featureCounts software v2.0.3  to compare the differential gene expression between samples. Using the read-out data as the input data for horizontal analysis, the differentially expressed genes (DEGs) were analyzed according to DEseq2 . All samples were performed in triplicate.Statistical analysis considered the mean value ± standard deviation (mean ± SD) and employed one-way analysis of variance (ANOVA) using SPSS 24.0 software . Statistical differences between treatments were considered significant at E. gracilis growth were explored under exposure to different concentrations of TCS . During the 96 h exposure, the E. gracilis cell density began to decline, compared with the controls , according to the toxicity classification of aquatic organisms (GB/T 31270.14-2014).The effects on controls a. With pcontrols b. The hitionship b. AccordE. gracilis cells after exposure to TCS had morphological deformities. TEM images were used to observe the microalgal ultrastructure after TCS exposure for 96 h  significantly decreased at high TCS concentrations (1.2 mg/L), compared to the control (p < 0.01)  a, and thmg/L TCS b. In conmg/L TCS c, reachimg/L TCS d. Thus, E. gracilis, TCS-E and TCS-H  that were significantly down-regulated, resulting in the significant inhibition of photosynthesis in E. gracilis, and all the other enrichment pathways shared genes with metabolic pathways.As shown in E. gracilis, an acute toxicity test was carried out. The results showed that TCS concentration formed a significant dose–effect relationship with the growth inhibition rate of E. gracilis  and Scenedesmus subspicatus (2.8 μg/L) and the EC50–72 h value of the diatom Navicula sp. (145.6 μg/L), E. gracilis (1820 μg/L) displayed stronger tolerance to TCS. This phenomenon may be related to the nutrients, water quality, and algal morphology required for the growth of the different algae. In addition, as a heterotroph, E. gracilis can survive in the dark, indicating that it may still survive after chloroplast damage, which may be the reason for the high resistance of E. gracilis to TCS, compared with other algae [In order to explore the toxic effect and mechanism of TCS on gracilis b, which nhardtii . The sener algae .E. gracilis cells after exposure to TCS had morphological deformities, which may be related to the occurrence of cell pellicule rupture and degradation [E. gracilis cells increased notably, indicating that toxic substances in the algal cell may be transferred into the vacuoles, where antioxidant molecules, such as glutathione S-transferase (GST), can protect or detoxify the algae [E. gracilis cells exposed to 0.3 and 1.2 mg/L TCS were slightly abnormal and loosely arranged, indicating that the growth of E. gracilis may be inhibited through toxicity caused by the exposure of chloroplasts to TCS. Electron microscope and TEM images were used to observe the microalgal cell damage after TCS exposure for 96 h a–h. In tradation . After ehe algae . CompareP. subcapitata to TCS also induced a reduction in photosynthetic pigments Chl a, Chl b, and photosynthetic activity [E. gracilis, resulting in the hindrance of chlorophyll synthesis, which is the main reason for the reduction in photosynthetic pigments and the inhibition of photosynthesis. Photosynthetic pigment content is an important toxicological test index of algae and is widely used to indicate the effect of pollutants on photosynthesis . As showactivity . CombineE. gracilis under TCS stress was studied to further understand its tolerance and adaptability to TCS stress. The activities of SOD and GSH, which are essential enzymes of the antioxidative system, were determined. An increase in SOD levels and an increase in GSH levels were caused by the elimination of excess oxygen free radicals and hydrogen peroxide in cells [E. gracilis [E. gracilis, which can further threaten the growth and reproduction of the population. Furthermore, the oxidative stress response of in cells . Meanwhiin cells . Moreovegracilis . In concE. gracilis might be greater (2−), hydroxyl radicals (OH•), and hydrogen peroxide (H2O2), are generated in cells when exposed to chemical stresses, such as metals, nanomaterials, and organic chemicals [E. gracilis, which is related to the changes in the antioxidant enzyme activity, and in addition, ROS production stimulated enriched pathways related to oxidative stress, which is the main mechanism of the toxic effects of TCS exposure in E. gracilis. In addition, through KEGG secondary pathway function and enrichment analysis, it was shown that both TCS-E and TCS-H exposure affected genes related to E. gracilis metabolism, suggesting that the metabolic mechanism of algae was blocked under greater toxicity, resulting in a corresponding stress response. This result was consistent with Liao et al. (2020) [E. gracilis in the gene pathways related to metabolism, suggesting that the metabolic mechanism of algae was blocked under the action of greater toxicity, resulting in a corresponding stress response. Studies have shown that organochlorines can induce inflammatory processes in organisms, stimulate oxidative stress responses, and have a bidirectional relationship with endocrine disorders, eventually leading to a variety of metabolic diseases [E. gracilis, especially the inhibition of photosynthesis by carbon and nitrogen metabolism.From the perspective of the transcriptome, the higher number of DEGs from TCS-H exposure suggested that the adverse effect of high TCS exposure on  greater a, indicahemicals . This re. (2020) , who foudiseases . As a ubdiseases . A greatTRINITY_DN96150_c0_g1 existing in multiple pathways , which could lead to the disorder of the TCA cycle metabolic system, including carbon and nitrogen metabolism. Herein, the down-regulation of metabolic pathways, as indicated by DEGs, and the change in ROS and the antioxidant enzyme activity mainly caused oxidative stress and photosynthesis inhibition in E. gracilis.The TCA cycle is a central pathway of primary metabolism for energy production , as showE. gracilis exposed to TCS exhibited an inhibition of population growth, with oxidative damage and metabolic pathways significantly altered. As the primary producer, the pollutants consumed by microalgae are easily transferred to larger organisms along the food chain, such as zooplankton, and is potentially harmful to the entire ecological environment and humans [E. gracilis not only brings more attention to the harm of pollutants in daily necessities, it also lays the foundation for adequate water environment management and studying the toxic effects of pollutants on other aquatic and terrestrial organisms.Based on the observed responses of physiological biomarkers and transcriptomic analysis, d humans . The inhd humans , which mE. gracilis), including morphological alterations, reduced photosynthesis, and oxidative stress, were investigated. Additionally, the cell’s own capacity for detoxification was surpassed by the ongoing stress of greater TCS concentrations (1.2 mg/L). It was shown that TCS, to some extent, interfered with the metabolism and gene information processing of E. gracilis, leading to neuronal death brought on by oxidative stress damage from functional analysis of DEGs utilizing the GO and KEGG pathways. Therefore, the main toxic mechanisms of TCS exposure to E. gracilis were the changes in ROS and antioxidant enzyme activities to stimulate algal cell damage and the inhibition of the TCA cycle metabolic system, including carbon metabolism, nitrogen metabolism, and D-glutamine and D-glutamate metabolism pathways controlled by the down-regulation of DEGs, which were further manifested as oxidative stress and photosynthesis inhibition effects. These results serve as a starting point for further investigation into the specific molecular pathways in microalgae that are affected negatively by the toxic effects of aquatic pollutants. At the same time, it provides theoretical guidance for the application of antibacterial agents in aquatic environments and promotes water environment management.In this study, the adverse effects of TCS on freshwater microalgae (


Conclusions: A significant proportion of patients (38%) do not use their hearing aid devices. Homogeneous multicenter studies using the same methodology are needed to analyze the causes of rejection of hearing aids.Purpose: To examine the prevalence of adherence to hearing aids and determine their rejection causes. Methods: This study was conducted according to the Preferred Reporting terms for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We performed an electronic search using PubMed, BVS, and Embase. Results: 21 studies that met the inclusion criteria were selected. They analyzed a total of 12,696 individuals. We observed that the most common causes for positive adherence to hearing aid use included having a higher degree of hearing loss, patients being aware of their condition, and requiring the device in their daily life. The most common causes for rejection were the lack of perceived benefits or discomfort with the use of the device. The results from the meta-analysis show a prevalence of patients who used their hearing aid of 0.623 . Both groups are highly heterogeneous (I2 = 99.31% in each group,  Currently, the rise in life expectancy has been accompanied by the unavoidable development of age-related concomitant diseases and morbidity, including hearing loss, which has a significant impact on life quality  and is oHearing loss suggests worsening cognitive deficit and mental processing, which could cause isolation and psychopathological problems, making integration into society more difficult ,4. PresbThere has been a constant 26% increase in years lived with disability for age-related and other types of hearing loss, which explains the rise in disability-adjusted life-years. In 2019, an estimated 1.57 billion people had hearing loss, accounting for one in five people. Of these, approximately 403 million people had hearing loss that was moderate or higher in severity after adjusting for hearing aid use, and 430 million without adjustment. Of all people with a hearing impairment, 62.1% were older than 50 years. By 2050, a projected 2.45 billion people will have hearing loss, a 56.1% increase from 2019, despite stable age-standardized prevalence .There are different articles in the literature that attempt to analyze the causes of why these patients with sensorineural hearing loss, who are hearing aid candidates, use or reject hearing aids. Despite significant developments and improvements in hearing aids over the last few years , some meDillon et al. (2020) showed significant variability in estimates of the non-use of hearing aids (mainly in studies conducted in developed countries). It is possible that, in addition to the variability between studies from different countries with different socio-demographic contexts, there is also variability within the same country. For instance, in the UK, the study by Aazh et al. (2015) estimated non-use at 10%, while Dillon et al. (2020) observed a prevalence of non-use at 18% ,13.Knudsen et al. performed an extensive search of the literature covering studies addressing help-seeking, hearing aid uptake, use, and satisfaction with hearing aids yielded 39 empirical studies published between January 1980 and January 2009. A total of 31 factors were examined in these studies. These were personal factors , demographic factors , or external factors . Whereas they found mixed results for most factors, they found that self-reported activity limitation as measured before treatment correlated positively with all four outcomes throughout all stages . This is a noteworthy finding demonstrating that self-reported auditory difficulty is highly important in aural rehabilitation, possibly more important than objective hearing sensitivity, which showed less consistent effects on outcomes. This result underlines the need to carefully consider what outcome  is the prime interest when designing rehabilitation programs. They conclude that whereas there is a large body of literature available on factors possibly influencing the different stages in the process toward help-seeking, obtaining a hearing aid, using it, and becoming satisfied with it, there are many issues that have not yet been investigated in controlled studies .Ng et al. reviewed a total of twenty-two articles. The identified four audiological determinants  and seven non-audiological determinants  as factors affecting the adoption and use of hearing aids. They concluded that there was a need to explore the influence of significant others, health professionals, and user demographics on hearing rehabilitation for future research .Our study aims to address the gaps identified in the systematic reviews mentioned above. We present a systematic review that analyzes the determining factors behind patients’ decisions to either reject or use their hearing aids.This study was conducted according to the Preferred Reporting terms for Systematic Reviews and Meta-Analyses (PRISMA) guidelines . FollowiIn our study, we conducted a comparison between group A  and group B . In group A, we included individuals who used their hearing aids, regardless of the duration of the use. In group B, we included individuals who either kept the device but did not use it or returned it.A comprehensive search strategy was conducted using the PubMed, Embase, and BVS  databases. We used a combination of medical subject headings and keywords to cover the following concepts: hearing aid, older adults, elderly, patient compliance, use, adherence, and acceptance. The search strategy was adapted to each concept to ensure comprehensive coverage of the relevant literature. The most recent search was conducted on 7th February 2022. The Boolean operators used are shown in We included studies that described the causes of the use or rejection of hearing aids based on the following criteria. For all eligible articles, data extraction was performed, and basic information was extracted.Inclusion criteria: publications from the last 25 years on adherence to hearing aid use in adult patients (over 18 years old), including the total number of patients with hearing loss, hearing aid candidacy, use or rejection of hearing aid, and its associated factors. The initial selection of the articles was based on the title and abstract of the articles, followed by a full-text assessment. The articles considered were those written in English, French, or Spanish. Articles had to include the following variables: age and gender of the participants, causes for use or rejection of the hearing aids, and total number of patients who used and who rejected the devices.All studies that did not meet the inclusion criteria were excluded.The search and article selection processes were independently conducted by two authors using the Rayyan tool .A descriptive analysis was conducted to examine the factors related to the use or rejection of hearing aids. This analysis included continuous variables , Student’s T-test for two independent samples was employed, and a meta-analysis of risk difference was conducted using a random-effect model to compare the prevalence of use or rejection of the hearing aid. The homogeneity and publication bias of the study were assessed. The statistical software JAMOVI was used along with the statistical packages R and MAJOR . The estimation of proportions for each study employed the restricted maximum likelihood as the model estimator, and the effect size model measure used the raw proportion. The restricted maximum likelihood method was also used. The methodological quality of each study was assessed using the ROBINS-I scale .Out of the initial 4199 articles identified through the search, 81 studies remained after screening titles and abstracts refer to . After cIn each article, various factors were associated with the rejection or use of hearing aids. Since these factors varied across the articles, we tried to homogenize the variables by grouping them. This allowed for a more consistent and comparable analysis of the factors influencing the decision to reject or use hearing aids across the selected studies.For the use of the hearing aids, we found factors that were grouped into the following categories: (1) higher degree of hearing loss or bilateral hearing loss. The classification of the hearing loss degree varied across the screened articles; (2) greater awareness of their condition; (3) greater satisfaction with the device, ease of use of the device, or having a simpler or more modern device; (4) higher economic status, higher income, higher level of education, having a university degree (the definition of high economic level may vary across the examined articles); (5) social issues ; (6) emotional causes, having a positive attitude; (7) greater experience using the device, using the device for more hours per day; (8) being Caucasian; (9) recent diagnosis, recent audiometry evaluation, regular medical monitoring; (10) older age; (11) being male; and (12) other comorbidities.Similarly, the causes for rejection were grouped as follows: (1) lack of awareness of their condition. This category includes factors related to individuals not being fully aware of their hearing loss condition or its impact on their daily life; (2) low or no perceived benefits from hearing aid use; (3) inability to understand others; (4) finding the device uncomfortable or difficult to use; (5) social stigma and other social causes; (6) lack of sufficient income. This factor relates to individuals not having enough financial resources to afford hearing aids or related costs; (7) lack of social or family support; and (8) older age.Based on the analysis of the selected studies, the most common causes for positive adherence to hearing aid use were identified as follows: (1) a higher degree of hearing loss: individuals with a more severe degree of hearing loss were more likely to adhere to the use of hearing aids; (2) awareness of their condition and daily necessity: individuals who were aware of their hearing loss condition and recognized the need for the device in their daily life were more likely to adhere to using hearing aids; (3) adequate income: having a higher income or sufficient financial resources was associated with positive adherence to hearing aid use; (4) greater experience using the device: individuals who had more experience using hearing aids and were familiar with their operation and benefits were more likely to adhere to their use. On the other hand, the most common causes for rejection of hearing aids were: (1) lack of perceived benefits: individuals who did not perceive significant benefits or improvements in their hearing or communication abilities with the use of hearing aids were more likely to reject them; (2) discomfort with the device: some individuals found the device uncomfortable to wear or experienced difficulties in using it, leading to rejection. Additionally, being older was identified as a factor that could both contribute to positive adherence to hearing aid use and rejection. The reasons for this dual association may vary and could be influenced by factors such as individual preferences, attitudes, or specific needs related to age .p < 0.05)  of 0.623, with a 95% confidence interval (CI) ranging from 0.531 to 0.714. The analysis also reveals high heterogeneity within both group A and group B, as indicated by an I2 value of 99.31, a Tau value of 0.211, and a significant Q value of 6421.241 ( < 0.05) . The ana < 0.05) . Figure The literature reveals various factors that contribute to the use or rejection of hearing aids, encompassing demographic, clinical, and device-related aspects. The rate of rejection typically falls within the range of 20% to 30%. However, if we consider patients who only use their hearing aids for a few hours a day, the rejection rate can increase to 40% . AdherenRegarding device-related factors, Fuentes López et al. found that 21.7% of patients discontinued using their hearing aids, with the majority ceasing usage within the first six months. The factors associated with increased usage were socioeconomic status, perceived degree of hearing loss, and satisfaction with the device . Humes eThe literature consistently highlights that a higher degree of hearing loss and greater awareness of one’s condition and perceived hearing loss are important factors that promote the use of hearing aids. Patients with moderate hearing loss are reported to use their hearing aids more frequently than patients with other degrees of hearing loss .Lee et al. identified individuals with daily professional and/or social activities for whom hearing loss significantly impacts their daily life as predictive factors for hearing aid use. These individuals have a greater awareness of their condition and recognize the necessity of using hearing aids .Simpson et al. found that it takes patients approximately nine years from the time of prescription to decide to use hearing aids. They also identified perceived needs and the social handicap associated with hearing loss as motivating factors for increased hearing aid use .A higher degree of hearing loss has been consistently associated with seeking help and a greater likelihood of using hearing aid devices ,40. McCoWhile most studies do not report significant differences between ethnic groups in terms of hearing aid use, there is some evidence suggesting that Black patients may use hearing aid devices less frequently compared to White patients ,42,43. TRegarding age, there seems to be variation in the factors influencing the use of hearing aids among different age groups. Younger patients may face economic challenges that hinder their ability to use hearing aids effectively, while older patients may encounter difficulties handling the devices. However, it is worth noting that different studies have provided conflicting findings regarding the relationship between age and hearing aid use. Some studies suggest that being younger is associated with a higher likelihood of using the device, driven by the need and willingness to rehabilitate , while oIncome and economic status have been identified as significant factors related to the rejection of hearing aid devices. Bainbridge et al. conducted a study on patients over 70 years old and found that the main reason for rejecting the device in their sample was the lack of sufficient income. They emphasized the importance of the public health system assisting these patients . SimilarThe role of doctors and healthcare professionals in promoting adherence to hearing aid use is crucial. Studies have shown that better adherence is associated with more frequent medical consultations and closer monitoring by healthcare professionals. Providing detailed information and regular monitoring increases patients’ motivation to seek information, try the devices, and ultimately use them ,31,32,35Including people over 18 years old may introduce significant heterogeneity in the prevalence estimates due to the wide age range and potential differences in factors related to hearing aid use. While the original intention was to focus solely on the elderly population, the decision to include individuals over 18 years old was made due to the larger number of articles available for analysis . Future Including studies from the past 25 years may introduce additional heterogeneity due to the significant changes in hearing aid technology during this period. As previously mentioned, the technology of hearing aid devices is a variable associated with their use, and advancements in technology can impact the prevalence and factors related to their use . StudiesIt is important to acknowledge that estimating a grouped prevalence with high heterogeneity may not provide specific and accurate information about any particular population subgroup. The estimate of 63.2% adherence to hearing aid use may represent an average prevalence based on the included studies, but the high heterogeneity suggests significant variability in the prevalence rates across different populations. Migliavaca et al. (2022)  highlighIt is also important to acknowledge that the variability in the information collected and reported by different studies can limit the comparability of results.There is also a high risk of bias, as measured by the ROBINS tool. The prevalence estimates presented in this review are based on the dichotomization between “people who use their hearing aids any amount of time” and “people who kept the device but did not use it at all or returned them”. However, the primary studies included in this review did not consistently use this dichotomization when studying variables associated with adherence. For example, Oyarzún et al. (2017)  used theThe heterogeneity among the studies may also be attributed to the use of different questionnaires by different authors. For instance, Aazh et al. (2014)  used theProspective studies with a homogeneous methodology focusing on the population over 65 years old are needed to establish the causes, and additional data on age, sex, income, and education are necessary to define specific profiles for each group.A significant proportion of patients (38%) do not use their hearing aid devices.Being aware of the need to use hearing aids and having a higher degree of hearing loss are important factors that promote their use.Homogeneous multicenter studies using the same methodology are needed to analyze the causes of rejection of hearing aids.Due to the heterogeneity and bias in the studies, it is not possible to objectively establish the causes for the use of hearing aids, and the quality of the evidence is low. There is heterogeneity among the studies included in this analysis, including non-randomized series, variation in the populations studied, different study designs, and diverse data collection methods. The wide age range and the inclusion of studies conducted over a long period, which encompasses changes in technology and social habits, further contribute to the heterogeneity. This increased heterogeneity suggests that the results may not apply to the overall population. Therefore, valid conclusions cannot be drawn regarding the characteristics and profiles of patients in each group.


The macula, as the central part of the retina, plays an important role in the reading process. However, its morphology has not been previously studied in the context of dyslexia. In this research, we compared the thickness of the fovea, parafovea and perifovea between dyslexic subjects and normal controls, in 11 retinal segmentations obtained by optical coherence tomography (OCT). With this aim, we considered the nine sectors of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid and also summarized data from sectors into inner ring subfield (parafovea) and outer ring subfield (perifovea). The thickness in all the four parafoveal sectors was significantly thicker in the complete retina, inner retina and middle retina of both eyes in the dyslexic group, as well as other macular sectors (fovea and perifovea) in the inner nuclear layer (INL), inner plexiform layer (IPL), IPL + INL and outer plexiform layer + outer nuclear layer (OPL + ONL). Additionally, the inner ring subfield (parafovea), but not the outer ring subfield (perifovea), was thicker in the complete retina, inner retina, middle retina (INL + OPL + ONL), OPL + ONL, IPL + INL and INL in the dyslexic group for both eyes. In contrast, no differences were found between the groups in any of the sectors or subfields of the outer retina, retinal nerve fiber layer, ganglion cell layer or ganglion cell complex in any eye. Thus, we conclude from this exploratory research that the macular morphology differs between dyslexic and normal control subjects, as measured by OCT, especially in the parafovea at middle retinal segmentations. Dyslexia has been defined as a neurodevelopmental disorder characterized by reading difficulties in the absence of psychiatric, neurological, auditory or visual disabilities . This diThe pathophysiology of dyslexia is still controversial and has been attributed to phonological, auditory or visual alterations ,4. A numSpecifically, the reading process starts with the projection of a well-focused image of the text onto the central part of the retina, called the macula. Then, this macular image is encoded by photoreceptors in a process called phototransduction, and transmitted through the chain of neurons of the visual pathway to the brain cortex to be interpreted . The macDespite the macula being such an important site for the reading process, no study is available about the macular morphology in dyslexia as far as we know. Thus, the aim of this research was to compare the thickness of different retinal segmentations between dyslexic subjects and normal controls at the macula, by the means of OCT.In this study, dyslexic and normal controls were prospectively recruited from the patients attending the hospital for a routine ophthalmic review at the General University Reina Sofia Hospital of Murcia, Spain.The inclusion criteria for the dyslexic group were: (1) Caucasian race; (2) Spanish as mother tongue; (3) aged under 25 years; (4) previous diagnosis of dyslexia confirmed by at least two different specialists; (5) refraction less than 6 spherical diopters and 2.5 cylinder diopters; (6) visual acuity of 20/25 or higher; (7) no history or findings of eye diseases or previous eye surgery; (8) no extraocular disease capable of modifying OCT measurements; (9) a reliable OCT scan (see below); (10) no other sensory, neurological, psychiatric, emotional or intellectual disorders; (11) no socio/economic significant disadvantage. Self-reported normal reader controls had the same inclusion criteria, except for criterion number 4. Only those participants not self-reporting reading difficulty and who correctly read aloud a simple 5-line paragraph text, without making a mistake or awkward pauses, were recruited in the control group.All the patients underwent a complete ophthalmic examination in both eyes, including visual acuity, autorefraction, air pneumatic tonometry, biomicroscopy and funduscopy. If the candidates were eligible, they underwent posterior pole horizontal protocol with 768 A- and 61 B-scans taken 30 × 25 degrees centered at the fovea, using a Spectralis OCT spectral domain device with an eye-tracking system . The OCT examinations were performed in the morning, between 8:30 and 12:30 h, with pupil dilation. During this examination, the mean thickness of nine sectors was determined for each considered segmentation using the 1, 3, 6 mm diameter Early Treatment Diabetic Retinopathy Study protocol, that is one of the most used OCT en face patterns to study the macula, which considers the fovea, parafovea and perifovea subfields b,c. The Then, with a segmentation tool , the thickness values of the following segmentations were automatically obtained: complete retina, inner retina, outer retina, retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL). The thickness value of the other segmentations was also obtained by summing up the thicknesses of the automatically obtained segmentations as follows: ganglion cell complex (RNFL + GCL + IPL), middle retina (INL + OPL + ONL), IPL + INL and OPL + ONL a. The thp-value less than 0.05 was considered statistically significant.The data analysis was conducted using SPSS version 22.0 . As there were no previous similar studies, no sample size calculation was performed in this investigation. The results of the right and left eyes were separately compared between the groups. Gender was compared between the groups by a Fisher’s exact test. The quantitative variables were assessed for normality distribution by inspecting histograms and using the Shapiro–Wilk test. Normally distributed variables were expressed as the mean and standard deviation, while non-normally distributed values were expressed as the median and interquartile range. Comparisons between two normally distributed variables were performed with the unpaired Student’s t-test. If at least one variable was non-normally distributed, the comparison between the groups was made by the Mann–Whitney test. A correction for multiple comparisons was not applied to this study in order to avoid the false-negative results . A p-valp = 1, Fisher’s exact test) or the left eyes .The OCT examinations of one right eye from the dyslexic group and two left eyes from the control group were discarded due to segmentation errors at one or more sectors. Finally, 89 reliable OCT scans from 46 participants were selected in this study: 24 right eyes  and 25 left eyes  were selected from 25 normal controls. Moreover, 21 right eyes  and 19 left eyes  were included from 21 dyslexic subjects. The gender between the dyslexic and control groups did not differ when considering the right  or for the left eyes .Similarly, the mean age was not different between the groups for the right eyes  , ganglioWhen considering the inner ring subfield (parafovea), we found that the complete retina, inner retina, middle retina (INL + OPL + ONL), OPL + ONL, IPL + INL and INL showed a higher thickness in the dyslexic group for both eyes, with IPL showing this difference only for the right eye . The resIn contrast, when dealing with the outer ring subfield (perifovea), only INL + OPL + ONL and INL showed a discrete increase of thickness in the dyslexia group, only when comparing the right eyes .This study found parafoveal thickenings in both eyes of the dyslexic group for the middle retina, mainly the ONL-related segmentations, but also for the INL-related segmentations . RemarkaThe ONL contains photoreceptor cell bodies and the INL bipolar, amacrine and horizontal cells nuclei. OPL and IPL are made up of axons and synapses and connect the neighboring nuclear layers  . In factA genetically determined disorder in foveal development could bring about the findings of the present study. This hypothesis is consistent with the fact that dyslexia presents a high degree of heritability (70% or even more), whereas the environment has little effect ,24,25.As a matter of fact, some genetic polymorphisms have been detected to be much more prevalent in dyslexia. These polymorphisms are in relation to abnormal axonal growth and defective neural migration ,27,28, aThe highest thickenings found in this study were located at the parafovea, although alterations at the fovea, and even at some perifoveal sectors, were also present in OPL + ONL and INL + OPL + ONL segmentations . The fovThe fovea and the parafovea work together in the reading process, because, although the fovea is oriented to the target word, the parafovea previews the next words to facilitate further foveal processing ,33. In fThus, the thickenings found in this study could constitute the morphological correlation of parafoveal dysfunction in dyslexia. These thickenings may theoretically cause a higher level of light scattering transmitted to the outer segments of photoreceptors, where the phototransduction takes place, and potentially a subsequent loss of sensitivity . The othIt is also remarkable that the thickening in all four parafoveal sectors 360 degrees) found herein is consistent with the fact that dyslexia is present in all languages, independently of the reading direction going from left to right , from right to left (Hebrew or Arabic) or from top to bottom  [0 degreesThis exploratory research also has its limitations. First, the sample size is small and the outcomes should be studied in larger groups, but we found significant results. Moreover, the facts that the comparisons have been calculated separately for the right and the left eyes and that the found differences are so similar in both eyes, affecting the same segmentations and with analogous disparities, reinforce the validity of our results . Second,From this exploratory research, we conclude that the macular morphology differs in dyslexic and normal controls, especially in the parafovea.