patients who had undergone previous keratoplasty have weakened corneal structure and are liable to have a wound dehiscence after being subjected to trauma [ 14 ] .
usually , the site of rupture globe is located at the host - graft junction [ 5 , 6 ] .
the explanation of this weak host - graft junction may be due to several factors such as inappropriate wound apposition , avascularity of the interface , prolonged treatment with topical steroids , and suture complications [ 69 ] .
deep anterior lamellar keratoplasty ( dalk ) has the advantage of no endothelial rejection because it maintains the recipient corneal endothelium .
this leads to less need for long term use of topical steroids with lower incidence of related complications such as glaucoma and infection [ 1013 ] .
another advantage of dalk over pkp is that it maintains better globe integrity , thus leaving the eyes less susceptible to trauma [ 14 , 15 ] . in the literature ,
reported cases of traumatic wound dehiscence following dalk are less than that reported following pkp [ 1521 ] .
the aim of the current study was to evaluate the patients ' characteristics , risk factors , complications , and visual outcome of traumatic wound dehiscence after keratoplasty .
this is a retrospective case series that included 20 eyes of 20 patients who had undergone a keratoplasty procedure followed by traumatic wound dehiscence .
those 20 patients represent around 4% of the total number of keratoplasty patients ' records scanned during the period between 2010 and 2014 .
the data recorded included the type of the keratoplasty procedure , the indication for the keratoplasty , sex , age at the time of the trauma , type of the trauma , the time interval between the previous keratoplasty and the trauma , size of the wound dehiscence , anterior segment complications , posterior segment complications , and visual outcome .
the wound was sutured with 10 - 0 nylon and if needed anterior vitrectomy and iris repositioning were performed .
the mean duration of follow - up after repair was 21 months ( range 13 to 48 months ) .
complete ophthalmic examination was done and final best spectacle corrected visual acuity ( bscva ) was measured .
this study was approved by the local research committee of faculty of medicine , alexandria university , egypt .
the ratio of males to females was 7  :  3 . the procedure of previous corneal transplantation was pkp in 16 eyes ( 80% ) and dalk in 4 eyes ( 20% ) .
thirteen eyes ( 65% ) had interrupted sutures and 7 eyes ( 35% ) had double running sutures .
the indication for keratoplasty was keratoconus in 11 eyes ( 55% ) , corneal opacity either postinfectious ( bacterial and herpetic ) or due to other causes in 5 eyes ( 25% ) , and pseudophakic bullous keratopathy in 3 eyes ( 15% ) , and one eye ( 5% ) suffered from congenital hereditary endothelial dystrophy .
the topical steroid eye drops used after the previous keratoplasty were prednisolone acetate 1% eye drops given 5 times a day for three months followed by gradual tapering over three months .
pkp patients were given topical steroid eye drops once daily for additional 6 months while dalk patients were given topical steroids eye drops once daily for additional 3 months .  
mean age at the time of trauma of the included eyes was 34.7  16.6 years ( range from 19 to 72 years ) .
mean duration between the time of previous keratoplasty and the trauma was 15.5  10.7 months ( range from 2 to 35 months ) .
ten cases ( 50% ) of traumatic wound dehiscence occurred during the first year following the keratoplasty procedure , four cases ( 20% ) occurred during the second year , and six cases ( 30% ) occurred during the third year ( p < 0.05 ) .
the causes included accidental hit by a door or a blunt object , minor trauma by a finger , falls , assaults , accidents , and sports injury .
the cause of trauma in elderly was falls in 2 cases ( 66.6% ) and blunt trauma in one case ( 33.3% ) .
none of the included patients had worn any protective eye wear following the keratoplasty procedure .
the site of the globe rupture in all cases was at the host - graft junction resulting in traumatic wound dehiscence of the previous keratoplasty procedure .
three eyes ( 15% ) had a wound involving three quadrants . in dalk cases ,
the extent of the wound dehiscence was as follows : 3 eyes ( 75% ) had a wound dehiscence involving two quadrants and 1 eye ( 25% ) had a wound dehiscence limited to one quadrant . using fisher 's exact test , there was no statistically significant difference ( p = 0.283 ) .
the site of the wound dehiscence in most of the cases ( 15 eyes ; 75% ) was either superonasal or inferotemporal .
in the cases of previous keratoconus , the wound dehiscence was more inferior than superior ( 7 eyes versus 4 eyes , resp . ) .
the associated anterior segment injuries included iris prolapse in 17 eyes ( 85% ) , traumatic aniridia in one eye , hyphema in 15 eyes ( 75% ) , and lens extrusion in 12 eyes ( 60% ) .
the associated posterior segment injuries included vitreous prolapse in 12 eyes ( 60% ) , vitreous hemorrhage in 11 eyes ( 55% ) , and retinal detachment within the first six months after trauma in 4 eyes ( 20% ) . in dalk cases , two eyes suffered from hyphema and two eyes suffered from lens extrusion and vitreous prolapse .
there was no statistically significant association relating dalk cases to lower incidence of anterior segment complications ( p > 0.05 ) .
none of dalk cases had retinal detachment or needed vitreoretinal intervention ( p = 0.001 ) .
ten eyes ( 50% ) had undergone regrafting because of graft failure ( 9 previous pkp patients versus one previous dalk patient ) .
three cases ( 15% ) suffered from intractable glaucoma that necessitated the need for implantation of ahmed glaucoma valve .
secondary intraocular lens implantation either alone or combined with another procedure such as regrafting was performed in 11 eyes ( 55% ) .
iris lens complex was needed in the case of traumatic aniridia and was implanted in combination with regrafting .
two cases suffered from complicated posterior subcapsular cataract and one of them had undergone cataract extraction with intraocular lens implantation .
iridoplasty was performed as a part of other surgical procedures , for example , secondary intraocular lens implantation or regrafting .
the other four cases had retinal detachment and underwent vitreoretinal surgery to repair the detachment .
the anatomical result was satisfactory except for one case that suffered from redetachment and underwent another vitreoretinal procedure with silicone oil tamponade .
this case had late graft failure and underwent regrafting and was left aphakic because of aniridia and difficult secondary intraocular lens implantation .
the best spectacle corrected visual acuity ( bscva ) of this eye was 0.1 in the final follow - up .
the final bscva was 0.1 or better in 5 cases ( 25% ) , was better than hand motions ( hm ) to less than 0.1 in 7 cases ( 35% ) , was hand motions ( hm ) or light perception ( pl ) vision in six cases ( 30% ) , and was no light perception vision in 2 cases ( 10% ) .
two cases of dalk had final bscva of 0.1 or better and the other two cases had final bscva between 0.1 and better than hm .
cases of dalk had better final visual outcome , but this was not statistically significant using fisher 's exact test ( p = 0.33 ) . as regards posttraumatic wound repair corneal astigmatism in the cases with clear graft , the mean corneal astigmatism after resuturing and before any second intervention was 5.50  1.55  d.
traumatic wound dehiscence after keratoplasty has a worse prognosis than other cases of traumatic globe rupture [ 6 , 22 ] .
it occurs in around 0.6 to 5.8% of patients with previous keratoplasty [ 14 , 23 ] .
the usual site of rupture is the host - graft junction indicating a weakness in this area despite wound healing .
cases with previous keratoplasty either pkp or dalk are liable to ruptured globe even from mild trauma . in the current case series , four cases of traumatic wound dehiscence following dalk procedure
cases reported in the literature of traumatic wound dehiscence following dalk are less than that reported following pkp [ 14 , 15 ] .
more than two thirds of the included patients were males and the most common indication for keratoplasty was keratoconus followed by other indications .
most authors report higher incidence of traumatic wound dehiscence after keratoplasty in younger age and in keratoconus patients [ 3 , 22 , 24 ] .
in contrast , some authors did not associate a higher incidence with younger age or keratoconus [ 1 , 25 ] .
keratoconus is a common indication for keratoplasty and keratoconus is common in younger age . also , younger age group especially males is more active and is more liable to trauma .
therefore , the previously mentioned factors are interrelated and can not be used to relate a higher incidence of traumatic wound dehiscence after keratoplasty with a weaker wound construction or other related factors to the healing process itself .
this higher incidence can be simply explained by more liability to trauma due to active lifestyle . in the current study
, the type of suturing technique was interrupted in two - thirds of the cases reported .
this agrees with other reports that showed continuous suturing technique to be more stable than interrupted suturing technique in preserving the globe from rupture [ 7 , 24 ] . as regards the duration between keratoplasty and the traumatic wound dehiscence , half of the cases occurred in the first year followed by the third and second years .
rehany and rumelt   explained that the higher incidence of traumatic wound dehiscence in the early period after keratoplasty could be related to wound weakness , visual rehabilitation following keratoplasty , and increased physical activity of the patients . in the current series , the mean duration between the time of trauma and the previous keratoplasty was 15.5  10.7 months ( range from 2 to 35 months ) . in the literature , this duration varied from 4 months to 7 years [ 1 , 7 , 22 , 24 ] .
although many studies reported higher incidence in the first two or three years following keratoplasty , [ 3 , 23 , 25 ] late occurrence has been reported indicating unstable wound that never reaches its original strength even late after keratoplasty [ 1 , 22 , 26 ] . as regards the mechanism of trauma ,
all the cases were subjected to blunt trauma from different causes . in elderly group , falls were more common .
the site of traumatic wound dehiscence was more common in either superonasal or inferotemporal quadrants ; this could be explained by the exposed temporal part of the globe that is less protected by bone . in keratoconus ,
inferior site of the dehiscence was more common ; this could be explained by thinner stroma and weaker wound in the inferior part due to the keratoconus pathology itself .
deep anterior lamellar keratoplasty cases seem to have less wound extent than pkp cases , but this was not statistically significant .
this needs larger number of reported cases of traumatic wound dehiscence following dalk to get a statistically significant difference . in the current series ,
lens extrusion occurred in 60% of the cases ; this could be explained by the extent of the wound dehiscence that was large enough to allow the lens to be extruded and the severity of the trauma itself .
other studies reported similar associated anterior and posterior segments injuries with variable incidence rates [ 1 , 3 , 5 , 27 ] .
reported similar incidence of iris prolapse ( 71.9% ) but lower incidence of hyphema ( 40.6% ) and lens extrusion ( 34.4% ) .
posterior segment complications included vitreous hemorrhage and retinal detachment which lead to poor prognosis and needed a further intervention .
graft failure could be explained by endothelial cell injury and corneal decompensation either from trauma or surgical manipulations .
none of the dalk cases had retinal detachment or needed vitreoretinal intervention , but the number of cases is too small to get a clinical conclusion or a statistically significant difference .
apparently , dalk seems to result in better corneal structure than pkp but this needs more reported cases of traumatic wound dehiscence following dalk for proper comparison with that following pkp .
as regards the final visual outcome , many studies report a poor visual outcome in cases of traumatic wound dehiscence after keratoplasty [ 1 , 2225 ] . in the current series
the other 75% had final visual outcome of less than 0.1 with 2 cases of no light perception vision .
jafarinasab et al .   reported that 43.7% of their patients had final visual acuity of hand motions or less .
cases of dalk seem to have better final visual outcome . this may be explained by less wound extent , decreased rate of rejection , better corneal wound integrity and preserved structure , and less posterior segment complications . in conclusion , traumatic wound dehiscence following keratoplasty results in poor visual outcome .
the dehiscence seems most likely to occur during the first year . whenever possible dalk should be used instead of pkp in young active persons especially males and who has keratoconus . as none of the cases wore protective glasses
, it would be a good idea to advise cases of previous keratoplasty to wear one .
femtosecond laser - assisted keratoplasty may offer better stability due to modified and more precise host - graft junction wound configuration .
 
 purpose . the study aimed at evaluating the patients ' characteristics , risk factors , complications , and visual outcome of traumatic wound dehiscence after keratoplasty . 
 patients and methods . 
 a retrospective case series that included 20 eyes of 20 patients who had undergone a previous keratoplasty procedure followed by traumatic wound dehiscence . 
 records of the selected patients were reviewed . 
 the mean duration of follow - up after repair was 21 months . included patients were recalled for the final follow - up visit . 
 results . 
 the procedure of corneal transplantation was penetrating ( pkp ) in 16 eyes and deep anterior lamellar keratoplasty ( dalk ) in 4 eyes . 
 the associated anterior segment injuries included iris prolapse in 17 eyes and lens extrusion in 12 eyes . 
 the associated posterior segment injuries included vitreous hemorrhage in 11 eyes and retinal detachment in 4 eyes . 
 the final bscva was 0.1 or better in 5 cases ( 25 % ) and was better than hand motions ( hm ) to less than 0.1 in 7 cases ( 35 % ) . 
 conclusion . 
 traumatic wound dehiscence following keratoplasty results in poor visual outcome . 
 cases following dalk may have less wound extent and better final visual outcome . 
 the dehiscence seems most likely to occur during the first year . 