The Brazilian elderly population is growing, and already represents 8,6% of our total population. Environmental factors, lifestyle, gender and genetics impact the development of presbycusis, which reduces quality of life.investigate audiologic and vestibular complaints in the elderly; perform tonal audiometry and check to see if there are differences between genders.Cross-sectional clinical prospective study.320 elderly patients (160 men and 160 women) were submitted to audiologic interview and tonal audiometry. The results were statistically analyzed by the following methods: ANOVA, Mann-Whitney and Chi-Squared.audiologic and vestibular complaints  were similar between the genders ; tonal audiometry showed a significant difference, with hearing loss in the high frequencies among men; and among women the curves were descending and flat. These results were statistically significant .our results lead us to conclude that, when the genders are compared, hearing loss in the elderly has similar symptoms; however, there are significant differences in tonal audiometry. In Brazil, the elderly situation started to appeal to different areas of society after 1976, when the first seminars were held to discuss the problems of the elderly in our society. Looking at census data from IBGEThe National Census of 1960 found that the Brazilian population was made up of 4.7% of elderly citizens, growing slowly to 5.1% in the 70's and reaching 6.1% of elderly citizens in the 80'sIn the year 2000 National Census, the elderly population was reported to represent 8.6% of the country's population, which means a total of 14.5 million people. In relation to 1991, there was a growth of 35.5% in the total number of senior citizens. In that year the ratio of these people in the general population was of 7.3% or 10.7 million senior citizensThe increase in the elderly population may suggest an association with the increase in average life expectancy of the Brazilian population, social indication of better life quality and social well being. However, even if we have raised the average life expectancy, this does not mean that objective conditions have improved for the elderlyBerkowitzZwaardemakerBunchCrowe et al.SchuknechtKirikae et al.Hansen & Reeske-NilsenSuga & LinsaySchuknechtIn relation to predisposing factors for hearing loss in the elderly, Glorig & NixonRosen et al.WestonHinchcliffeGilad & GlorigAnderson & MeyerhoffAccording to MaderAccording to GatesThe study carried out by Cruickshanks et al.The interaction between noise exposure and presbycusis was also investigated and showed that there are more complex mechanisms than a simple summation of losses. In experiments with animals, they were exposed to low-to-moderate noise intensity for a long period of time, in short and high intensity duration this mechanism does not seem to be exactAbout the presence of symptoms associated with hearing loss in the elderly, Bora et al.According to Schneider et al.Rosenthall & KarlssonOn the other hand, labyrinth symptoms may also accompany the symptoms of hearing loss and would accrue from the incidence of degenerative alterations in the vestibular system, such as degeneration of the saccular nerve bundle and of its neuroepithelium, as well as its saccular otolithic system and, in a lesser degree, that of the utricular otolithic systemAccording to Huang et al.The goals of the present investigation were to study the hearing and labyrinthine complaints from a sample of the Brazilian elderly population and characterize the audiometric profile of these elderly, assessing the differences between genders.We carried out a cross-sectional study in a secondary level outpatient ward, in a region where most of the elderly population is needy (classes D and E)The series comprehended a group of 320 individuals with one or more audiological or associated labyrinthine complaints , with a minimum age of 60 years (“elderly) for males and females.The subjects were asked about the presence of the aforementioned complaints. We also investigated the presence of worsening factors of hearing loss in the elderly, such as systemic blood pressure, diabetes mellitus, hyperlipidemia, smoking and exposure to occupational noise, in order to better characterize the population under study.We performed threshold tonal audiometry, determining the thresholds for both air as bone conduction. Hearing loss type was defined according to Santos & RussoIn order to compare the results between genders, we used the ANOVA and Mann-Whitney tests to analyze the quantitative variables and the Chi-Squared for the qualitative variables. The significance level (α) to reject the null hypothesis was fixed at 5% . We used the EpiInfo, version 3.3.2 software package.The analysis of the elderly (n=320), according to age and gender, presented two homogeneous groups, of normal distribution and with a statistically significant difference .Table 1DThe investigation of the factors that worsen the hearing loss in the elderly showed a high percentage of cardiovascular and metabolic disorders, and also extrinsic factors, such as smoking and noise exposure . There wAmong the symptoms investigated, hearing loss was the most frequent, followed by tinnitus, dizziness and ear fullness  and 3. WAs far as tonal audiometry is concerned, we noticed an important ratio of asymmetry between the ears, without association with gender . SensoriAbout the most common type of curve, there was a predominance of deeper hearing loss in the higher frequencies when compared to the lower frequencies (descending curves) for both genders  and 8. NWith the results of the tonal thresholds and considering a moderately severe hearing loss (>55dBHL), in low and high tones, as a sign of hearing loss worsening, we found a relationship between aging and a hearing loss worsening only in men (p<0.05). When we considered a moderate level of hearing loss (>41dB NA), such association becomes even more evident, with p<0.001 .Table 2DBased on the results obtained from the descriptive analysis of the elderly population investigated, we can notice that the two groups formed , as far as age is concerned, have normal distribution, with similar data variability, thus favoring statistical inference reliability.We observed a high incidence of hearing loss worsening factors in the population studied, especially those with high blood pressure , smoking and noise exposure in men  and hyperlipidemia in women (30.0%). Many authors, from Rosen et al. and his research with the Mabbans until more recent ones such as Huang, have investigated the interaction of cardiovascular diseases and other extrinsic factors with presbycusisThe incidence of tinnitus  in our study was higher when compared to other studies involving senior citizens About dizziness, there was a relationship with gender (p<0.05), being more common in the elderly women (20.0%). In their investigation, Kamierczak & Doroszewska concluded that despite not finding any difference in the distribution of dizziness between elderly men and women, vertigo was more frequent in women. Moreover, multisensory deficits, drugs or systemic diseases common to senior citizens may cause vertigo. According to the results from tonal audiometry, we noticed an increase in auditory thresholds, especially in higher frequencies in both genders. However, a worse hearing loss in higher frequencies was more evident in men when compared to women, and this may be seen through the higher percentage of descending curves among males (85.0% in both ears) when compared to women .On the other hand, we observed a significant relationship between females and audiometric high and low tone alterations. This relationship was characterized by the presence of horizontal curves very frequent in elderly women (20.6% in both ears). And this was not seen among men .The stepwise rise in hearing thresholds with frequency increase was already expected in both genders, since presbycusis is a sensorineural hearing loss that develops first and more severely in the higher frequencies, because, according to the histology studies carried out by Crowe et al. and Schuknecht, there is an organ of Corti dystrophy and that of the cochlear branch of the vestibule-cochlear nerve in the cochlear baseMany other authors have stated that in the elderly there is a higher rise of auditory thresholds in the higher frequenciesNonetheless, there would be some differences in hearing loss development when we compare men to women. Males usually present more pronounced hearing loss in the higher frequencies; while in women it happens in the lower frequencies, at around 500HzStudies carried out in our settings have also confirmed a gradual hearing loss as the person ages, and it is more pronounced in the higher frequencies when compared to the lower frequencies for both genders. However, women have more horizontal audiometric curves than menIn his study with 912 individuals of both genders, with ages varying between 18 and 65 years, Corso concluded that women had better tonal thresholds for higher frequencies than men, even though the opposite happens for the lower frequencies (250 and 500Hz)1.age-related hearing loss onset is more stepwise for women than for men;2.once started, the hearing loss develops faster for women, although the relative hearing loss in low frequencies for them are greater than those in men;3.age-related hearing loss rate is more uniform in women; for men this rate varies with age in a less uniform fashion.The author explained this phenomenon stating that:Moller and Kryter related this fact to women having less hearing loss for the higher frequencies because of their work as housewives, less exposure to noxious noises than men. Thus, their hearing thresholds reflect, more homogeneously, the hearing loss accruing from the aging processAnd finally, when we tried to correlate the age increase with hearing loss worsening, we found a worsening in the tonal thresholds only in men . In womeThe results found in this study led us to conclude that, when we compare genders, hearing loss in the elderly has -except for dizziness - similar symptoms and significant differences in tonal audiometry.


On the other hand, the decrease in Nicotinamide adenine dinucleotide (NAD +) levels is reported to be closely related to the age-related declines in physiological functions such as ARHL in animal studies. Moreover, preclinical studies confirmed NAD + replenishment effectively prevents the onset of age-related diseases. However, there is a paucity of studies on the relationship between NAD+-related metabolites at baseline and pure-tone hearing thresholds at different frequencies  in 42 healthy Japanese men aged > 65 years were analyzed using Spearman’s rank correlation. Multiple linear regression analysis was performed with hearing thresholds as the dependent variable and age and NAD+-related metabolite levels as independent variables.This study was analyzed the baseline results of our previous clinical trial, in which nicotinamide mononucleotide or placebo was administered to 42 older men . The correlations between blood levels of NAD+ precursor in the Preiss-Handler pathway) and right- or left-ear hearing thresholds at frequencies of 1000 Hz , 2000 Hz , and 4000 Hz . Age-adjusted multiple linear regression analysis revealed that NA was an independent predictor of elevated hearing thresholds (1000 Hz (right): p = 0.050, regression coefficient (β) = 1610; 1000 Hz (left): p = 0.026, β = 2179; 2000 Hz (right): p = 0.022, β = 2317; 2000 Hz (left): p = 0.002, β = 3257). Weak associations of nicotinic acid riboside (NAR) and nicotinamide (NAM) with hearing ability were observed.Positive associations were observed between levels of nicotinic acid  on 1st June 2019.The online version contains supplementary material available at 10.1186/s12877-023-03796-3. Age is a risk factor for several diseases, such as diabetes, cardiovascular disease, cancer, and Alzheimer's disease . Aging a content –4. Moreo content –4. If th+ biosynthetic pathways: the de novo pathway, Preiss-Handler pathway, and salvage pathway [+ [+ catabolite NAM is converted to NMN in a rate-limiting step catalyzed by nicotinamide phosphoribosyltransferase (NAMPT) via the NAD+ salvage pathway [NAD + related-metabolites are derived from three main NAD pathway . The Pre pathway  or is pr pathway . NA is cthway [+ . NAD+ ca pathway –7.+ metabolism and ARHL has been identified in animals. SIRT3, one of the seven mammalian sirtuins, is a mitochondrial NAD+-dependent deacetylase that controls key metabolic pathways [+ metabolite, activates the NAD+-SIRT3 pathway and prevents noise-induced hearing loss and spiral ganglia neurite degeneration in mice [+ metabolite, was administered to healthy older men daily for 6 or 12 weeks. Chronic NMN administration partially improved muscle performance  in healthy older men and tended to improve audibility in the right ear, although the change was not statistically significant [+ metabolism in humans is limited.Age-related hearing loss (ARHL) is one of the most common age-related disorders in older adults. ARHL is underscored by hearing impairments and speech communication disability caused by physiological age-related changes in the organum auditus and central nervous system circuits related to the auditory system. The World Health Organization defines disabling hearing loss as hearing loss greater than decibels hearing level (dB HL) in both ears, and hearing loss of 35 dB HL or greater in the worse ear . The conpathways  and has pathways . SIRT3 dpathways . Moreove in mice , 12. Recnificant . However+ metabolites and hearing ability in older adults and analyzed the clinical data of older Japanese men that were obtained in our recent human clinical study [Therefore, we aimed to investigate the correlation between NADal study .+-related metabolites and hearing ability using the baseline values obtained in our previous study [This study was a sub analysis evaluating the association between NADus study . The preus study .+ metabolites and aging-related parameters, including hearing ability, were measured and evaluated as secondary objectives.The studies were approved by the Graduate School of Medicine and Faculty of Medicine, University of Tokyo Research Ethics Committee 2018013P) and registered as “Randomized, double-blind, placebo-controlled parallel-group comparative study to evaluate the effect of NMN on the body composition in elderly persons” at UMIN-CTR (UMIN000036321). 65 Japanese older men volunteers were recruited by NEWING NPO Corp , which is a third-party nonprofit organization. After some screening tests to assess eligibility for the NMN-supplementation study, in total 42 healthy Japanese men aged > 65 years were enrolled in this study. The details of the inclusion and exclusion criteria have been described in the previous study [P and regAll participants provided written informed consent to participate in the study. The study was conducted in accordance with the guidelines of the Declaration of Helsinki at the Clinical Research Support Center Phase 1 Unit of the University of Tokyo Hospital.Participants fasted and visited the Clinical Research Support Center Phase 1 Unit of the University of Tokyo Hospital in the morning. The blood samples were collected from forearms of the participants. The samples in heparinized tubes were frozen at -80 °C and analyzed at the University of Toyama. The extraction and analysis of NAD + related metabolites , NANM, NMN, NR, and NAM) were performed as previously described .50 µL of whole blood and 450 µL of 50% MeOH were mixed and vortexed for 10 s, followed by the addition of an equal volume of chloroform (500 μL). The mixture was centrifuged at 13,000 × g at 4 °C for 10 min, and then aqueous phase and organic phase were separated. The upper aqueous phase was transferred to a new tube, and this liquid–liquid extraction was repeated. After this procedure, the samples were dried. The dried aqueous phase was reconstituted in LC/MS-grade water. The metabolites were analyzed by using an Agilent 6460 Triple Quad mass spectrometer  and Agilent 1290 HPLC system (Agilent Technologies Inc.). Analytes were separated on an Atlantis T3 column  using mobile phase A (5 mM ammonium formate) and mobile phase B (methanol) at a flow rate of 150 µL/min and column temperature of 40 °C. In addition, the programmed mobile phase gradient was following: 0–10 min, 0–70% B; 10–15 min, 70% B; 15–20 min, 0% B. Analysis of chromatograms were performed by using MassHunter Quantitative Analysis software (Agilent Technologies Inc.). Various concentrations of the standard compounds were measured to make standard curves for quantification.Hearing ability of the right and left ears was measured by using an audiometer . Participants wore dedicated headphones in a quiet room and listened to acoustic pure-tone signals. If participants responded at 40 dB, the volume was lowered by 10–20 dB until no response was seen, and then the volume was gradually raised by 5 dB until participants responded. The volume level at which participants responded again was recognized as their hearing threshold. Besides, if there was no response at 40 dB, the volume was increased by 10–20 dB until a response was observed. Then, the volume was decreased by 10–20 dB until no response was seen, after that the volume was gradually increased by 5 dB until participants responded again. The volume level at which participants responded again was recognized as their hearing threshold. The same procedures were followed in order to measure and evaluate pure-tone air-conduction hearing thresholds at frequencies of 2000 Hz, 4000 Hz, 8000 Hz, 500 Hz, 250 Hz, and 125 Hz, in the order .+-related metabolites (µM) and hearing thresholds (dB HL) were analyzed using Spearman’s rank correlation coefficient. Multiple linear regression analysis was also performed to assess the age-adjusted correlation between hearing threshold (dB HL) and whole-blood concentrations of NAD+-related metabolites (µM) by designating hearing threshold as the dependent variable and NAD+-related metabolites and age as the independent variables. The regression coefficient represents the amount of hearing threshold (dB HL) when the NA (μM) changes by 1 μM. Outliers were defined as values outside of the third quartile + 1.5 × quartile range as the maximum and the first quartile -1.5 × quartile range as the minimum. The correlation coefficients and p-values analyzed by excluding outliers are presented in parentheses in Figs. p < 0.05.Statistical analysis of the data from the 42 participants was performed using Easy R for Microsoft Windows . Correla+-related metabolites , and hearing thresholds at each frequency, are presented in Table Japanese men aged 65–88 years participated in the study. The clinical characteristics of the 42 participants, including the mean and SD of age, blood concentrations of NADr = 0.307, p = 0.048)       Fig. B, 1000 H+ related metabolite levels and hearing thresholds at each frequency. Our data indicated that age and blood NAD+ levels were not correlated in participants aged more than 65 years. Nevertheless, an age-related decrease in NAD+ and reciprocal increase in plasma NAM has been reported among a sample of participants with a wide age range (20–87 years) [+-related metabolite levels as the independent variables in the following analyses.Spearman’s rank correlation coefficient test was basically conducted to identify the correlation between NAD7 years) . Since ar = 0.480, p = 0.001)   = 1610, 95% confidence intervals (CI) = 0.840 to 3220; 2000 Hz: p = 0.022, β = 2317, 95% CI = 348 to 4286)      , 7. The 01) Fig. B and 200r = 0.454, p = 0.004, left: 1000 Hz ),2000 Hz  and 4000 Hz  : p = 0.028, β = 2419, 95% CI = 274 to 4563; 2000 Hz (right): p = 0.001, β = 3782, 95% CI = 1585 to 5979; 2000 Hz (left): p < 0.001, β = 5968, 95% CI = 3777 to 8159; 4000 Hz (left): p = 0.024, β = 3743, 95% CI = 519 to 6966)  and left-ear hearing threshold at 8000 Hz  in Spearman’s rank correlation tests    : p = 0.171, β = 6197, 95% CI = -2783 to 15,176; 2000 Hz (left): p = 0.036, β = 10,156, 95% CI = 679 to 19,633)     and left-ear hearing thresholds at 500 Hz , 1000 Hz , 4000 Hz , and 8000 Hz   with hearing thresholds at each frequency using Spearman’s rank correlation tests , and power = 0.702 (correlation coefficient = 0.4)). Additionally, participants comprised healthy Japanese men aged 65 years or older. The results may be relevant only for the certain healthy older Japanese men. Further investigations including other races, generation, and gender are warranted. Moreover, as all analyses were exploratory, multiple comparisons were not performed. However, the significant correlation between NA levels and hearing ability were observed at the same frequencies (1000 and 2000 Hz) on both ear sides in our analyses. While this consistency is not explained by false positive results, we consider our findings deserves further investigation to confirm our findings. Finally, the mechanism of ARHL requires further elucidation from the perspective of the NADRT3 axis  in basic+ metabolic pathways, particularly the Preiss-Handler pathway, to the development of ARHL should be further investigated in future studies.In conclusion, we report a negative correlation between whole-blood concentrations of NA and hearing ability. The relevance of NADAdditional file 1: Supplementary Table 1. The correlations between age and the level of NAD+ related metabolites. The correlation between age (year) and NAD+ related metabolites (μM). Comparisons were made using the Spearman’s rank correlation coefficient. The correlation coefficients and p-values analyzed excluding outliers are presented in parentheses. Supplementary Table 2. The correlation between the level of NAD+ and hearing thresholds at each frequency. The correlation between the level of NAD+ (μM) and right or left-ear hearing thresholds at each frequency (dB HL). Comparisons were made using the Spearman’s rank correlation coefficient. The correlation coefficients and p-values analyzed excluding outliers are presented in parentheses. Supplementary Table 3. The correlation between the level of NAMN and hearing thresholds at each frequency. The correlation between the level of NAMN (μM) and right or left-ear hearing thresholds at each frequency (dB HL). Comparisons were made using the Spearman’s rank correlation coefficient. The correlation coefficients and p-values analyzed excluding outliers are presented in parentheses. Supplementary Table 4. The correlation between the level of NMN and hearing thresholds at each frequency. The correlation between the level of NMN (μM) and right or left-ear hearing thresholds at each frequency (dB HL). Comparisons were made using the Spearman’s rank correlation coefficient. The correlation coefficients and p-values analyzed excluding outliers ae presented in parentheses. Supplementary Table 5. The correlation between the level of NR and hearing thresholds at each frequency. The correlation between the level of NR (μM) and right or left-ear hearing thresholds at each frequency (dB HL). Comparisons were made using the Spearman’s rank correlation coefficient. The correlation coefficients and p-values analyzed excluding outliers are presented in parentheses. Supplemental Figure 1. The correlation between the level of NAR and hearing thresholds at each frequency. (A) The correlation between the level of NAR (μM) and right or left-ear hearing thresholds at each frequency (dB HL). (B) The correlation between the level of NAR and right-ear hearing thresholds at 250Hz. (C and D) The correlation between the level of NAR and left-ear hearing thresholds at 1000Hz(C) and 2000Hz(D). Comparisons were made using the Spearman’s rank correlation coefficient. The correlation coefficients and p-values analyzed excluding outliers are presented in parentheses. *P < 0.05; **P < 0.01


Ontogenetic changes in the habitats and lifestyles of animals are often reflected in their visual systems. Coral reef fishes start life in the shallow open ocean but inhabit the reef as juveniles and adults. Alongside this change in habitat, some species also change lifestyles and become nocturnal. However, it is not fully understood how the visual systems of nocturnal reef fishes develop and adapt to these significant ecological shifts over their lives. Therefore, we used a histological approach to examine visual development in the nocturnal coral reef fish family, Holocentridae. We examined 7 representative species spanning both subfamilies, Holocentrinae (squirrelfishes) and Myripristinae (soldierfishes). Pre-settlement larvae showed strong adaptation for photopic vision with high cone densities and had also started to develop a multibank retina (i.e. multiple rod layers), with up to two rod banks present. At reef settlement, holocentrids showed greater adaptation for scotopic vision, with higher rod densities and higher summation of rods onto the ganglion cell layer. By adulthood, they had well-developed scotopic vision with a highly rod-dominated multibank retina comprising 5–17 rod banks and enhanced summation of rods onto the ganglion cell layer. Although the ecological demands of the two subfamilies were similar throughout their lives, their visual systems differed after settlement, with Myripristinae showing more pronounced adaptation for scotopic vision than Holocentrinae. Thus, it is likely that both ecology and phylogeny contribute to the development of the holocentrid visual system. Summary: Coral reef fishes in the family Holocentridae remodel their retina at the cellular level to adapt to a nocturnal lifestyle during development. Vision is important to the behaviour and survival of most vertebrates . Owing tThe INL contains the nuclei of interneurons, such as bipolar, horizontal and amacrine cells, and their synapses are located within the inner plexiform layer (IPL), which represents the primary stage of opponent processing for colour vision . FinallyIn general, differences in the organisation and densities of the retinal cell types correlate well with ecological demands . For insOver ontogeny, many marine fishes experience significant ecological shifts. As larvae, most marine fishes inhabit a bright and broad-spectrum light environment  in the uFor species that adopt bright environments, visual development is characterised by typical changes in the cellular architecture of the retina. Specifically, the retina is initially cone-dominated, and the densities of cones, INL cells and GC increase early in development and then decrease slightly , while rod densities undergo a minor increase . ContrasHere, we investigated visual development at the cellular level in the nocturnal reef fish family, Holocentridae. Holocentridae comprises two subfamilies: Holocentrinae (squirrelfishes) and Myripristinae (soldierfishes). As larvae, both subfamilies inhabit the upper pelagic ocean and feed on zooplankton . During Sargocentron, Neoniphon and Myripristis) covering both subfamilies, as well as an adult for a deeper-dwelling species (Ostichthys sp.). We used this approach to address the following aims: (1) to assess how the holocentrid visual system changes as they shift from being predominantly active in bright light to dim light, and (2) to study the development of their deep-sea-like multibank retina.While the visual systems of adult holocentrids have been described in detail, their development is poorly understood. Hence, we used a histological approach to examine anatomical structure and cell densities in the retina at key ontogenetic stages . We studied shallow reef-dwelling species from three genera .Details of all animals used in this study are given in −1 phosphate-buffered saline (PBS), pH 7.4] depending on the analysis (see below for details).Fish collection and euthanasia followed procedures approved by the University of Queensland Animal Ethics Committee (QBI 304/16). Briefly, fish were first anesthetised by immersion in a solution of 0.2 ml clove oil per litre of seawater until respiration and all response to light and touch had ceased and were then euthanised by swift decapitation. All collections within Australia were conducted under a Great Barrier Reef Marine Park Permit (G17/38160.1) and Queensland General Fisheries Permit (180731) and all collections in French Polynesia were conducted in accordance with French regulations. Following euthanasia, all individuals were photographed adjacent to a ruler and their body size  and eye diameter were subsequently measured from photographs using Fiji v.1.53c , five settlement larvae , two settled juveniles  and ten adults . All animals were sampled in the light-adapted state except for the pre-settlement larvae and the adult Ostichthys specimen, which were dark adapted. To account for intraretinal variability . Briefly, a small square of retina was dissected from each region, post-fixed in 2.5% glutaraldehyde and 2% osmium tetroxide, dehydrated in ethanol and/or acetone, and embedded in EPON resin (ProSciTech). All tissue processing was done in a BioWave Pro tissue processor (PELCO).Retinal histology was conducted on PFA-fixed eyes from the following individuals: three pre-settlement larvae  on a Zeiss Axio upright microscope (Imager Z1) and brightfield images acquired with Zeiss Axiocam 506 mono and 512 colour microscope cameras. Rod outer segment (ROS) length, PRL thickness, and whole retinal thickness were then measured from micrographs using Fiji. A body size range at which the full complement of banks  was reached was determined by comparing total length in individuals with the full complement to the maximal total length published in FishBase .Radial 1-μm-thick retinal sections were cut with a glass knife on a Leica ultramicrotome (Ultracut UC6) and stained with a solution of 0.5% Toluidine Blue and 0.5% borax. Retinal sections were viewed with a 63× objective , and in two species in the same genus for Myripristinae because of a limitation in the number of specimens at specific stages . However, to make sure that the data were comparable between the different species from Myripristinae, the densities in settlement M. kuntee were also compared to one settlement M. berndti and the densities in adult M. berndti were compared to one adult M. kuntee . Briefly, using Fiji, images were cropped to obtain retinal strips of 250 μm  for lower-density cell types (i.e. cones and GCL cells) in adults, 100 μm for lower-density cell types in larvae, and 40 μm for higher-density cell types (i.e. ONL and INL cells) for all life stages. These counting frames were optimised by conducting trials with several frame sizes and taking the minimum frame size that produced counts ≥95% similar to those attained with the largest frame (assumed to be the most accurate). The number of cone OS, ONL nuclei, INL nuclei and GCL nuclei were counted for three sections per sample using the cell counter plugin in Fiji. Subsequently, counts were corrected for section thickness using Abercrombie's correction .Retinal cell densities were estimated from transverse retinal sections, a method widely employed for marine teleosts for over 50 years . Cell derrection  and the  the GCL . Graphs S. rubrum (the only species obtained at this stage) had two rod banks in the dorsal retina but only one bank in the ventral retina . Across the family, the full complement of banks was attained by the time fish reached 40–60% of maximal size.Retinal sections were taken at different life stages from species in each subfamily in Holocentridae to assess the structure of their multibank retina. In all species and stages, rods were arranged in banks in at least part of the retina. Moreover, rod banking increased with size/age. Pre-settlement larvae of l retina . In settl retina . Settlem17 banks . FinallyS. microstoma; Myripristinae: M. berndti), the addition of rod banks between settlement larvae/settled juveniles and adults resulted in an increase in the PRL thickness (In species from both subfamilies (Holocentrinae: hickness . The reghickness .Table 1S. rubrum) and Myripristinae    were estimated in different regions of the retina for species in Holocentrinae (berndti) . In S. rregions) , Table 3Myripristis spp. , a comparison between stages was done using the two species to increase sample size. Between settlement and adulthood, cone, INL cell and GCL cell densities decreased across the retina by 92–96%, 77–90% and 90–95%, respectively. Concurrently, rod densities and rod:GCL summation increased by 104–294% and 2123–6592%, respectively.A similar developmental pattern was observed in tis spp. , Table 3S. rubrum retained these peak densities in the temporal retina, while Myripristis spp. shifted its peak cone and GCL cell densities centrally, and its peak INL cell densities ventrally. Conversely, rod densities did not peak in the same regions for S. rubrum and Myripristis spp. at either stage , or until 20–47% of the maximal size is reached (for bathypelagic fishes) (Table S1), until they reached 40–60% of their maximal size. However, this may be found to be even earlier if more intermediate sizes were examined. Moreover, most banks were added after holocentrids settled on the reef and transitioned to a dimmer environment. Whether the addition of rod banks was driven by the exposure to dim light is still unknown. However, light environment has consistently been shown to be the dominant driver of visual adaptations in marine fishes  . Similare fishes  and thusFurther evidence for light environment as a driver of multibank retina development comes from an examination of intraretinal and interspecific variability in bank numbers. This variability has been reported in some adult deep-sea fishes  as well Despite the prevalence of multibank retinas, their function remains a mystery. Two main non-mutually exclusive hypotheses have been proposed: (1) multibank retinas enhance luminous sensitivity  and/or . ResultsMost teleosts commence life with a pure cone retina, with rods added later . While mM. berndti: ∼2.6 million rods mm−2 vs. Myctophum brachygnathum: ∼2 million rods mm−2 and Hoplostethus atlanticus: ∼1.7 million rods mm−2) (M. berndti: 3800:1 vs. Lampanyctodes spp.: 2000:1 and Chauliodus sloani: 200:1)   and thei: 200:1) . Finally: 200:1)  and the : 200:1) .Retinal specialisations in teleosts usually reflect ecological demands  and, accAfter holocentrids have settled on the reef and adopted their nocturnal lifestyle, their retinal specialisations shift accordingly . In adulThe holocentrid visual system adapted to life in dim light over ontogeny. At the morphological level, they increased rod banks from 1-2 to 5-17, adopted a rod-dominated retina and increased visual summation. Despite the early emergence of the multibank retina, substantial topographic specialisations in bank number were only evident after the transition to a dimmer environment. Together, this suggests that ecology drives visual development in Holocentridae. However, subfamily-specific differences in the degree of scotopic specialisation emerged over development  and these were correlated with phylogenetic relatedness to deep-water representatives rather than ecology. This suggests that the development of the holocentrid retina may also be somewhat driven by phylogeny. Future studies on visual development in other nocturnal reef fishes, as well as other marine fish families with both shallow- and deep-water forms, such as Anomalopidae (flashlight fishes) and Engraulidae (anchovies), may provide further insights into the ecological and phylogenetic drivers of the development of dim-light vision.


The study aimed to evaluate audiological benefits, quality of hearing and safety of two Bonebridge generation: BCI601 and BCI602  in children.Twelve children were implanted: five BCI601 and seven BCI602 comprising of ten conductive hearing loss, and two single sided deaf SSD subjects. Audiological outcomes tested were sound field audiometry, functional gain, speech recognition threshold (SRT50), speech recognition in noise (SPRINT) and localisation abilities. Subjective measures were Speech, Spatial and Qualities of Hearing Scale (SSQ12).The mean FG with the BCI601 was 25.0 dB and with the BCI602 28.0 dB. The benefit in SRT50 was 23.2 dB and 33.8 dB, respectively. The mean benefit in SPRINT was 15% and 6.7% and the localisation ability improved from 33.3° to 16° and from 26.2° to 17.6°, respectively. The two SSD subjects reported a FG of 17 dB, a benefit in SRT50 of 22.5 and a benefit in SPRINT of 20%. Subjective outcomes improved significantly and even exceeded the values of their age-and sex matched normal hearing peers. One revision was reported: a retroauricular emphysema above the implant occurred 12 months post-OP, it was resolved operatively with the implant still being functional.The pediatric cohort reports significant audiological benefit, even exceeding that of the age- and sex matched control. The combination of the high safety and audiological benefit makes the Bonebridge a comfortable and effective option in hearing rehabilitation in children. In general, all implant recipients exhibit a wide range of speech perception skills with a range of factors identified affecting clinical performance despite of the degree and type of hearing loss . Hensch The aim of this study was to evaluate the audiological outcomes, benefits, and safety of the two generations, the BCI601 and BCI602, implanted in twelve children . To the best of knowledge of the authors, this is the second study on the new Bonebridge BCI602 , as wellThe prospective data analysis and implantation was performed as part of routine clinical procedures between January 2018 and December 2020 at the tertiary centre. The study protocol was approved by the ethics committee of University Hospital  and informed consent of the parents/legal guardian was given prior surgical intervention. The audiological inclusion criteria were based on manufacturer’s recommendations and paediatric patients suffering from CHL and SSD were included  and 3 months post-operative (post-OP) in a soundproof audiometric booth, using the audiometer Interacoustics AC40E .Pure tone measurements were performed at a frequency range from 0.5 to 4 kHz. Pure tone average air (PTA4AC) and bone (PTA4BC) conduction hearing thresholds were calculated as the mean of the evaluated AC and BC values at 0.5, 1, 2 and 4 kHz.Sound-field thresholds were measured using frequency—modulate warble tones presented from the aided side, with the loudspeaker positioned 3 m away from the subject. Soundfield audiometry (SF), speech recognition threshold (SRT50) and speech recognition in noise test (SPRINT) at 65 dB HL in a multi-talker babble were performed. The contralateral ear was masked with narrowband noise during pure-tone and sound field audiometry, and with broad band noise during the speech tests. The noise level was determined by the experienced audiologist as necessary. All audiological examinations were performed with (aided) and without the bone conduction hearing device (unaided) and with temporary hearing aid used before implantation (previous HA). In four children with CHL, localisation testing was performed with a circular, ten loudspeaker arrangement. The localisation test tool v.1.0 provided by MED-EL was utilized, using a stimulus of different white noise types and a stimulus level of 40 dB. The outcomes were separated into the stimulus provided from the front or from the back for better visualisation purposes displayed in Fig. The Speech, Spatial and Qualities of Hearing Scale (SSQ 12) questionnaire was designed to measure auditory disability across a wide variety of domains, reflecting the reality of hearing in everyday life . Items aR score was generated to test for the correlation efficiency. The Root Mean Square Localisation Error (RMSE) was calculated as a function of unaided versus aided conditions, for both implant generations separated as well as for signals presented from the back and from the front (°) , baseline characteristics (e.g. aetiology), and patient-reported outcomes mean, SD, median, minimum and maximum Table . The non°) Table ; Fig. 4.n = 9)] and two from SSD were included. Five were implanted with the BCI601 and seven with the BCI602 . The two SSD subjects have each received a BCI601 and a BCI602. The study cohort comprised of six females and six males. The mean age at implantation was 12 ± 3.5 years, ranging from the youngest with 6 years up to 19 years of age. Prior to surgery all subjects trialled different Bone Conduction Hearing Devices, such as the ADHEAR, BAHA Softband, Cross Hearing and Contact Mini. Even though Soundfield outcomes with the previous HA were quite satisfying . In all patients, the transmastoidal (TM) approach was carried out. For the BCI602 placement, only pre-OP CT scans were visually inspected without further planning. No complications occurred during surgery. BCI lift was used only in one patient implanted with a BCI601. In four subjects, the emergency screw had to be used because of an inferiorly localised screw due to a highly pneumatised mastoid tip and thin superficial bone. In two patients, the dura was exposed (BCI601 and BCI602) and compressed by 1 mm. The sigmoid sinus was compressed in one patient (BCI601). Detailed peri-operative course and device models BCI601 or BCI602 are depicted in Table P = 0.098), but was not significantly different when compared to previous hearing aids used 28.0 ± 2.4 (P = 0.125) (Table P = 0.036) and was significantly different when compared to previous hearing aids used 29.0 ± 5.5 (P = 0.036) (Table P = 0.125). For the six subject with the BCI 602, the mean SRT50 improved from 67.0 ± 9.6 dB in the unaided condition to 33.2 ± 7.4 dB in the aided condition (P = 0.031). Merging the ten subjects resulted in a highly significant improvement in SRT50 (P = 0.006).The outcomes of the two SSD subjects reported pre-OP mean in SRT50 of 52.5 ± 17.1 which improved to 30 ± 14.1 after Bonebridge treatment (one device generation each). The mean SPRINT outcomes exhibited pre-operative mean level of 80 ± 14.14% and improved to a mean of 100% after implantation. The pre-OP SF was 39 ± 1.8 dB HL and with previous HA 26 ± 0.88 dB HL and improved to 22 ± 0.88 dB HL. Due to the low number and the equally distributed outcomes, the SSD subjects were not separately according to their device analysed nor was statistical analysis possible. The analysis of the CHL cohort implanted with the BCI601 resulted in a significant improvement from the mean pre-OP value of hearing threshold in sound field of 48.00 ± 6.6 compared to the BB-aided condition 23.00 ± 3.7 dB HL (n = 2) a mean of 85.0 ± 7.1% and improved to 90.0 ± 0.0% post-OP (statistics N/A). In the BCI602 study group, five subjects understood with the device 90% ± 10.0%, which improved from 83.3 ± 15.3 in the pre-OP condition. Only the total CHL cohort comprising of seven measured subjects showed a statistically significant improvement with a P value of 0.038.The speech Speech Recognition in Noise Test (SPRINT) exhibited in the BCI601 cohort (°) on the x-axis is plotted against the answers of the users, shown as the stimulus response plots. The correct answers with sound stimulus from the front barely correlated with the trend line resulting in a Pearson R of 0.51 for the BCI601 and with the BCI602 a Pearson R of 0.8 in the unaided condition was observed. These outcomes improved in the BCI601 aided condition to R = 0.8 and R = 0.91. Sound localisation ability with the stimulus given from the back resulted in a correlation of the trend line in the BCI602 and BCI602 of R = 0.65 and R = 0.68 in the unaided conditon and improved to R = 0.88 and R = 0.91 in the aided conditon, respectively. The calculated root mean square error (RMSE) with signals from the front in the unaided condition was 34.5° and improved to 17° in the aided condtion for the BCI 601. Similar results were observed in the BCI602 implanted subjects with signals from the front (18.8° and 21.3°). Investigating the results for the BCI601 with signals presented from the back a RMSE of 32° was observed in the unaided condition which improved to 15° in the aided condition. Similar results were seen for the BCI602 subjects, were the RMSE improved from 31.1° when unaided to 16.5° in the aided situation  which was also seen for the subcategories of Speech, Spatial and Qualities of Hearing . The rating for the BCI601 implanted cohort was also significantly better when compared to the pre-OP condition (P = 0.063), which was rated even better in the BCI602 implanted study group (P = 0.031). The sames device-respective statistical significance was found in the subdomains of Speech, Spatial and Qualities of Hearing measured . The SRT50 significantly improved in the BCI602 group with an average gain of 33.8 dB after implantation. The lack of significant benefit in the BCI601 group, even though the outcomes improved to 34.3 dB (gain 23.2 dB) may be again due to the relatively low number of subjects (n = 4). Nonetheless, these outcomes are in accordance with the recent reported literature [. As compared to the previous model BCI601, the new BCI602 provides nearly 50% less drilling depth due to reduction of the BC-FMT thickness from 8.7 to 4.5 mm and flexible implant positioning, which opens up new possibilities for difficult pathologies up to implanting children younger than the age of five including a wide range of anatomies and underlying pathologies [Audiological performance tests were chosen to best reflect everyday hearing situations, hence real-life benefit. The beneficial rehabilitation of hearing should also be reflected in post-operative subjective evaluation of quality of hearing, which in in our experience was often lacking a correlation of objective measures, such as speech reception and/or localisation ability, and the patient’s objective expectations and self-assessment of their hearing abilities. We, therefore, utilized the Speech, Spatial and Qualities of Hearing via a short questionnaire SSQ12). Pleasingly, our subjective audiological measures go hand in hand with the subjective, patients’ self-assessment: showing significantly improved localisation abilities paired with significantly improved dimension of spatial hearing in the questionnaire—outcomes apply for both device generations. On the other hand, we observed, that the pre-operative bone conduction hearing aid trial of up to three months was in terms of SF measurements quiet successful, nonetheless the patients still opted for an implantable solution. We conclude this from the fact (and after correspondence with the parents), that either the stigmatisation, especially in that particular age-group was too high (mean age at implantation was 12 ± 3.5 years), the speech understanding, particularly in challenging environments such as classrooms and at parties, was not sufficient enough and/or the wearing comfort was not given, as for most of those devices, except the ADHEAR, high pressure for optimal sound transmission through the skin is required . A wide 2. Pleasi dB gain .2 dB mayterature –26. Espeterature . Vyskociterature . Our resterature . The firterature , 30, 31 terature , such coterature . Most chhologies , the othhologies . So far,hologies .Most of the reports in the literature on the results of Bonebridge implantation in children have employed small study groups with a maximum of up to 20 patients. Our report uses a similar sample size, which is limitation of the study and further investigations with higher subject numbers should be employed in the future. Such reports might be brought together as part of a meta-analysis which could draw much stronger conclusions about the safety, efficacy and effectiveness of this solution for children.All children, as well as their parents, were very satisfied with both implanted generations of the Bonebridge: the BCI601 and the BCI602. Sound-field audiometry, speech audiometry, speech audiometry in noise as well as localisation abilities showed a significant benefit after implantation. Subjective assessment of hearing quality as investigated via the SSQ12 improved significantly after implantation. The combination of the high safety and significant objective as well as subjective benefit makes the Bonebridge (both generations) a comfortable and effective option for hearing rehabilitation in children suffering from CHL or SSD.


Hearing loss is a growing public health concern associated with decreased health-related quality of life (HRQoL) and a negative impact on work life. Knowledge about the long-term benefits for patients receiving cochlear implants may provide knowledge imperative for policymakers to promote better HRQoL and working life outcomes for individuals with hearing loss. The purpose of this study was to explore how HRQoL, hearing disabilities, and work satisfaction outcomes changed in working-aged adults with severe to profound hearing loss from pre- to post-receiving a cochlear implant (CI) between the baseline, year one, and year two. This longitudinal study used Cochlear’s Implant Recipient Observational Study (IROS) registry data to assess HRQoL, hearing disabilities, and work satisfaction in 18–65-year-old CI recipients. Data were collected pre- and post-implantation at baseline, year one, and year two follow-up. One hundred and twenty-seven CI recipients participated in the study. Significant improvements were observed for HRQoL outcomes for hearing, speech, emotion, and health utility post-implant. Overall hearing disability decreased post-CI, and work satisfaction improved. With the increasing prevalence of hearing disabilities, this is pertinent knowledge that supports the use of CIs for hearing rehabilitation which may promote better HRQoL and work satisfaction. In 2021, the World Health Organization (WHO) launched a report that addressed hearing health as a global public health priority . HearingTo increase hearing function in individuals with HL, hearing technologies, such as hearing aids and cochlear implants (CIs), can be used to generate a representation of sounds from the environment ,11. CIs With a global growing prevalence of HL, it is pertinent to explore the long-term benefits for patients receiving CIs which may provide knowledge imperative for policymakers to promote better HRQoL and working life outcomes for individuals with HL. The overarching purpose of this study was, therefore, to explore how HRQoL, hearing disabilities, and work satisfaction outcomes changed in working-aged adults with severe to profound hearing loss from pre- to post-receiving CIs between baseline, year one follow-up (YR1), and year two follow-up (YR2).This study had a longitudinal design with repeated measures at baseline, YR1, and YR2 follow-up. Participants in the study received three different questionnaires including measurements for generic HRQoL, levels of hearing disabilities, and work satisfaction at the three measure points. The study process and reporting of findings were guided by the checklist Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) .Implant Recipient Observational Study (IROS) [ClinicalTrials.gov NCT02004353] which contains data collected from clinicians and CI recipients between years 2009–2020 [Data was obtained from Cochlear’s international registry, the 009–2020 . IndividUniwersytetu Medycznego w Łodzi, RNN/117/12/KE), Spain , and South Africa  according to institutional and national research standards. Participants received verbal and written information about the purpose of the study before providing signed informed consent to participate.The IROS study was approved by Ethical Review Boards of participating centres in Colombia , Germany , Hungary , Poland , a 15 item survey with eight health attributes: vision, hearing, speech, ambulation, dexterity, emotion, cognition, and pain/complaints . The insHearing disabilities were measured by the 49 item instrument The Speech, Spatial and Qualities of Hearing Scale (SSQ), which measures hearing disabilities on a scale ranging from 0  to 10  across the domains of speech hearing, spatial hearing, and qualities of hearing . Speech Employment status and work satisfaction were assessed by questions, e.g., if the participant was employed (yes/no), grade of employment (part-time/full-time), job classification (multiple choice categories), job title (free text), satisfaction with the job (yes/no), and if their hearing ability had negatively affected the daily work satisfactory . No definition was given for the concept of “satisfaction” as individuals assign different meanings to what they find satisfactory, and, as such, it was understood from the viewpoint of the participant’s personal interpretation. Unemployed participants were asked if they were retired (yes/no), their level of satisfaction being unemployed (yes/no/don’t know), and if they believed that their hearing ability was the reason for not being employed (yes/no/do not know). Employed participants were asked about the impact on hearing ability through the hearing device(s) related to the daily work, if there had been any changes over the last 12 months compared to before having the implant surgery (yes/no), and if the device(s) enabled them to do their job now .n) and percentage. Continuous data, i.e., age, was calculated as a mean value with standard deviation (SD). The HUI-3 and SSQ subscale and global score data were analysed by Kolmogorov–Smirnov and Shapiro–Wilk tests and by examining histograms to determine the normality distribution. For the SSQ data median values were imputed for individuals who had occasionally missing data (<1%). Subscales and global score means for HUI-3 and SSQ as well as work satisfaction summary scores were compared between baseline and YR1 with Wilcoxon Signed rank test and with Friedman’s test between baseline and across YR1 and YR2. Categorical data were compared between baseline and YR1 with McNemar’s test and with Cochran’s Q test between baseline across YR1 and YR2. Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 28.0. All statistical tests were conducted by using a significance level of p < 0.05.Descriptive statistics were used for background information. Categorical variables are presented with number  years of age, and about two-thirds were female (63%). Participants were located in six different countries with most residing in South Africa (46.5%) and Spain (31.5%). Nine out of ten received one CI. The etiology of participants’ HL displayed that it was unknown what had caused the HL in approximately half of the cases. More than half of the participants reported to have tinnitus pre-implantation. Seventy percent of participants stated to be employed, and the majority were in full-time employment. Of the employed participants, the largest proportion were academic professionals (32.6%) followed by semi-skilled trained workers (25.8%), non-academic professionals (23.6%), and unskilled workers (10.1%). A smaller group of participants reported to have “other” occupations (7.9%). Only nine participants of the sample stated that they had a comorbid condition. A more detailed account of participants’ socio-demographic and clinical background information at baseline can be seen in p = 0.020). The aggregated difference between baseline and YR2 for hearing was 0.104 (p < 0.001). For speech, there was a significant change in scores of 0.015 between baseline and YR1 and YR2 follow-ups (p < 0.010). The attribute emotion had a significant difference of 0.0047 (p < 0.001) between baseline and YR1 and YR2. Cognition showed a significant change in scores of −0.006 (p < 0.004) between baseline and YR1 and YR2 follow-ups. For the health utility score, a significant increase of 0.169 (p < 0.001) was seen between baseline and YR1 and YR2 follow-up.Results for HUI-3 scores between baseline, YR1, and YR2 follow-up showed significant changes in HRQoL values for the attributes hearing, speech, emotion, cognition, and the overall health state utility score . For thep < 0.01, but no domain was significant between YR1 and YR2).The result for hearing disability measured by the SSQ instrument showed that there was an improvement in scores for patients post-CI implantation between baseline, YR1, and YR2 follow-ups . ChangesA visual display of the distribution of the data from the aggregated SSQ global score at baseline, YR1, and YR2 follow-up is shown as boxplots in p = 0.017). A significant increase could, however, not be seen between YR1 and YR2. Patients also stated that they, to a lesser extent, experienced their hearing ability to have a negative impact on the satisfaction of executing their daily work at YR1 and YR2 post-CI as compared to baseline. At baseline, patients’ summary score for their mean impact of hearing on their work was 2.521 (SD ± 0.852), indicating that, on average, their hearing negatively impacted their ability to work sometimes/most of the time. At YR1, patients scored their mean impact of hearing on their work at 1.603 (SD ± 0.640), indicating that, on average, their hearing impairment negatively impacted their ability to work not at all/sometimes. At the YR2 follow-up, the mean summary score was estimated at 1.575 (±0.622). Hence, there was a significant difference in mean score between baseline and across the YR1 and YR2 follow-ups of 0.946 (p < 0.001)Eighty-nine patients in the sample were employed at baseline, as some individuals in the sample recently retired or were currently undertaking studies . The empn = 70), and presented a health utility score of 0.49 at baseline and 0.56 at follow-up [This study identified overall increases in HRQoL that were significant for the attributes hearing, speech, emotion, and the aggregated health utility value between baseline and across the follow-ups in individuals who received CI implants. However, there were more prominent increases in HRQoL between baseline and YR1 and YR2 follow-ups compared to between YR1 and YR2. This suggests that there may be a larger initial effect post-CI implantation that levels out and potentially remains steady over time. A possible explanation that aligns with this finding may be that respondents attained stable CI programming parameters after the first switch-on, meaning stimulation levels usually obtain a fast evolution during the first weeks after activation of the sound processor. Then, the evolution becomes slower, and the programming parameters tend to be stable about six months after the initial switch-on . The staollow-up . The subp < 0.001) between baseline and YR1 and YR2 follow-up, this denotes considerable clinical importance of CIs, as differences of 0.03 are considered clinically meaningful [p = 0.020) and 0.104 (p < 0.001) between the baseline and YR2, which suggests a substantial and clinically important improvement.Comparing the baseline health utility score for individuals with HL in this study, which was estimated at 0.481, with other chronic diseases from a Canadian study also shows that the mean health status is worse than for the utility norms of living with the effects of stroke (0.581), urinary incontinence (0.621), and mood disorders (0.643). Furthermore, the improved scoring at YR1 and Y2, set at 0.653 and 0.650, respectively, is similar to the utility norms for chronic obstructive pulmonary disease (COPD) (0.649) . This inaningful . Similaraningful , and it The findings for work satisfaction revealed that the majority of the employed participants were generally satisfied with their work at baseline (86.5%), a number that increased at YR1 follow-up (96.5%) and had a smaller drop in YR2 (91.6%). Participants also reported that, to a lesser extent, their HL negatively impacted their ability to work between the baseline and YR1 and YR2 follow-ups. This result aligns with a previous systematic review concluding that receiving CIs had a positive effect on the working life of individuals with HL in terms of better work performances related to, e.g., improved communication with colleagues and increased functioning . From a Limitations of the study include that there was no control group, which weakened the ability to draw conclusions about outcomes due to threats associated with validity. However, being a pre- and post-study with two follow-ups gives the advantage of enabling the assessment of patterns that may occur over a longer period that could not be observed over shorter periods of time. A further strength of this study is that the reliability was controlled for by using the instruments HUI-3 and SSQ to assess HRQoL. These instruments have been validated for responsiveness for individuals with HL and used in numerous studies for this patient group ,27. In aIn conclusion, overall hearing quality increased post-CI and work satisfaction improved. With the increasing prevalence of hearing disabilities, this is pertinent knowledge that supports the use of CIs for hearing rehabilitation, which may promote better HRQoL and work satisfaction.