Long-Term Outcomes of Penetrating Keratoplasty for Keratoconus with Resolved Corneal Hydrops

CLINICAL SCIENCE

Long-term Outcomes of Penetrating Keratoplasty for Keratoconus With Resolved Corneal Hydrops

Sayan Basu, MBBS, MS,* Jagadesh C. Reddy, MBBS, MS,* Pravin K. Vaddavalli, MBBS, MS,* Geeta K. Vemuganti, MD,† and Virender S. Sangwan, MBBS, MS*

cute corneal hydrops develops when sudden spontaneous Purpose: To address the controversial issue of whether the Arupture of the Descemet membrane (DM) leads to bullous occurrence of corneal hydrops adversely affects the fate of sub- corneal edema, in eyes with progressive keratectasia.1 It is sequent penetrating keratoplasty (PK), this study compared the long- a rare complication of keratoconus affecting only 2% to term outcomes of PK in keratoconic eyes with resolved corneal 3% of cases and is associated with severe ocular allergy.2,3 hydrops with those without prior corneal hydrops. Resolution is spontaneous and 31% to 63% of patients 2,3 Methods: This was a retrospective chart review of 102 eyes of 102 recover useful vision with contact lenses. However, poor patients with keratoconus who underwent PK. The primary outcome vision because of central corneal scarring or contact lens – intolerance necessitates a penetrating keratoplasty (PK) in measure was endothelial rejection free allograft survival and the 2–4 secondary outcomes were vision, postoperative complications, and 20% to 59% of patients. histopathologic findings of corneal buttons obtained during PK. Among the numerous studies that have reported the long-term outcomes of PK in keratoconus,5–18 only two pre- Results: The mean follow-up after PK was 5.5 ± 3.3 years. The vious studies have explored the association between corneal Kaplan–Meier endothelial rejection–free allograft survival at 1 and hydrops and allograft rejection/survival but with conflicting 5 years post-PK were 93.7% ± 4% and 82.6% ± 7%, respectively, in results.3,4 Although Tuft et al3 noted that eyes with resolved 32 eyes with hydrops and 100% and 98% ± 2%, respectively, in hydrops had significantly higher chances of endothelial 70 eyes without hydrops (P = 0.04). Multivariate analysis showed rejection episodes compared with those without hydrops that the risk of endothelial rejection episodes was greater in eyes (20% vs. 5%; P = 0.02), Akova et al4 noted fewer allograft with longer duration of corneal hydrops (P = 0.019) and coexistent rejection episodes in the hydrops group (6% vs. 11%; ocular allergy (P = 0.012). All rejection episodes were reversed P = 0.7). Tuft et al3 postulated that rejection episodes may medically and only 1 allograft failed because of postoperative be more common after hydrops because of the associated endophthalmitis. More than 90% of eyes achieved a visual acuity ocular allergy and/or vascularization; however, this associa- of better than 20/40. Common postoperative complications were tion was not tested statistically. To address this controversial cataract and graft infiltrate. Histopathology in cases of resolved issue, in this large case series, we compared the long-term hydrops after intracameral gas showed unique compression artifacts clinical outcomes of PK in keratoconic eyes with resolved like folding and burial of the broken ends of Descemet membrane corneal hydrops with those without prior corneal hydrops. in the stroma. Conclusions: Although endothelial rejection episodes are more METHODS common in eyes with resolved corneal hydrops, long-term allograft Patient Selection survival and visual results after PK in eyes with keratoconus are This study followed the tenets of the Declaration of excellent, irrespective of prior corneal hydrops. Helsinki and was approved by the Ethics Committee of the Key Words: acute corneal hydrops, keratoconus, penetrating L V Prasad Eye Institute, Hyderabad, India. This was keratoplasty, allograft rejection, allograft survival, histopathology a retrospective interventional study of patients with clinically diagnosed keratoconus who underwent corneal transplanta- (Cornea 2012;31:615–620) tion between January 1995 and December 2009. Exclusion criteria were cases in which (1) the treatment and/or duration of corneal hydrops could not be reliably ascertained, (2) lamellar keratoplasty was performed, (3) PK was performed Received for publication January 10, 2011; revision received July 10, 2011; for nonoptical indications, (4) PK was performed before accepted August 4, 2011. complete clinical resolution of corneal hydrops, and (5) From the *Cornea and Anterior Segment Service; and †Ocular Pathology post-PK follow-up was less than 1 year. Laboratory, L V Prasad Eye Institute, Hyderabad, India. Supported by the Hyderabad Eye Research Foundation. The authors state that they have no financial or conflicts of interest to disclose. Data Collection Reprints: Sayan Basu, Cornea and Anterior Segment Service, L V Prasad Eye Institute, Kallam Anji Reddy Campus, Rd No.2, Banjara Hills, All patients underwent a comprehensive ophthalmic Hyderabad, India (e-mail: [email protected]). examination at each follow-up visit. The medical records of Copyright © 2012 by Lippincott Williams & Wilkins the eligible patients were reviewed by 1 examiner (S.B.), and

Cornea Volume 31, Number 6, June 2012 www.corneajrnl.com | 615 Basu et al Cornea Volume 31, Number 6, June 2012 the relevant demographic and clinical data were collected yearly from 1 to 5 years and 10 years postoperatively. All other in predesigned spreadsheets. Acute corneal hydrops was de- postoperative complications after PK were also noted. fined clinically as sudden onset of bullous corneal edema in eyes with keratoconus with or without an identifiable break in Statistical Analysis the DM on slit-lamp examination. Duration of corneal hydrops All statistical analysis was performed using MedCalc was calculated from the date of onset of symptoms to the date version 11.3 for Windows (MedCalc Software, Mariakerke, of complete disappearance of corneal edema on slit-lamp Belgium). Means with SDs were reported for all normally examination. Associated ocular allergy was diagnosed based distributed continuous variables. Preoperative features, post- on symptoms of itching and/or eye rubbing along with clinical operative vision, and complications were compared using the signs of papillary reaction on the tarsal and/or limbal conjunc- x2 – fi test (Yates corrected). Kaplan Meier survival analysis was tiva. An endothelial rejection episode was de ned clinically as performed to estimate the cumulative probability (reported as the acute onset of anterior uveitis with keratic precipitates on the percentage with standard error) of endothelial rejection–free graft endothelium and overlying graft edema. allograft survival. Univariate (log rank test) analysis was done to identify the variables associated with allograft survival, Interventions which were subsequently fitted in a multivariate (Cox During acute corneal hydrops, all patients received proportional hazard) model to estimate their relative effect tapering doses of topical steroid (prednisolone acetate on allograft survival (after checking all the assumptions and 1%), lubricant (carboxymethyl cellulose sodium 0.5%), interactions of the model). A P value of less than 0.05 was hyperosmotic (sodium chloride 5%), and cycloplegic considered to be statistically significant. (homatropine hydrobromide 2%) eye drops until the clinical resolution of corneal edema. Some patients also received a single intracameral injection of 14% perfluor- RESULTS 2 opropane (C3F8)gas. AstandardPKprocedurewasper- Demographic and Baseline Data formed for all patients, under local or general anesthesia, Of the 442 eyes of 398 patients who underwent using donor corneas stored in McCarey Kaufman medium, corneal transplantation for keratoconus in the study period, with a 0.25 to 0.5 mm over sizing of the donor corneal 102 eyes of 102 patients were included in the study (255 eyes button and 10-0 nylon interrupted suturing. All patients with inadequate post-PK follow-up, 66 eyes undergoing were seen again on day 1, day 7, and day 30 postopera- anterior lamellar keratoplasty, 12 eyes treated elsewhere for tively. Subsequent follow-up and selective suture removal hydrops, 5 eyes operated before resolution of hydrops, and were performed according to the discretion of the treating 2 eyes undergoing therapeutic PK were excluded). The age ophthalmologist. All patients received topical steroid of the patients at PK was 20.4 ± 9.5 years. In the 32 patients fl (prednisolone acetate 1%) and antibiotic (cipro oxacin with corneal hydrops, the age at acute hydrops was 19.6 ± 0.3%) eye drops for 1 week postoperatively after which 9.3 years, duration of corneal hydrops was 4.3 ±2.6 months the antibiotic was discontinued and the steroids were (2.25 ± 1.5 months in 8 C3F8-treated eyes and 4.1 ± tapered gradually. After the initial 3 to 6 months, most 1.6 months in other 24 eyes), and the duration between patients were maintained on a once daily or twice daily resolution of hydrops and PK was 11.2 ± 7.2 months. Table 1 dosing of steroid eye drops. In the event of an endothelial shows that at the time of PK, eyes with hydrops had rejection episode, the topical steroid dosage was inten- asignificantly higher association with ocular allergy than fi si ed, starting from every 1 hourly, and tapered according others (P , 0.0001). to the response. Systemic steroids were not administered for endothelial rejection episodes. Primary Outcome The Kaplan–Meier endothelial rejection–free allograft Histopathology Findings survival rates were 98% ± 1% at 1 year, 92.9% ± 3% at The corneal buttons of all 102 cases were retrieved 5 years, and 87.3% ± 5% at 10 years (Fig. 1A). The endo- from the Ophthalmic Pathology Laboratory. The hematoxylin thelial rejection–free allograft survival rates at 1, 5, and – and eosin and periodic acid-Schiff stained sections of 10 years postoperatively were 93.7% ± 4% and 82.6% ± fi fi formalin- xed paraf n-embedded tissues were reviewed by 7%, respectively, in 32 eyes with hydrops and 100%, 98% 2 observers (G.K.V. and S.B.) and evaluated with special ± 2%, and 90.1% ± 6%, respectively, in 70 eyes without attention to the appearance of DM and endothelium. hydrops (P = 0.04; Fig. 1B). An endothelial rejection episode occurred in 7 eyes (6.8%), all of which were reversed with Outcome Measure intensive topical medication. None of the eyes had epithelial The primary outcome measure was endothelial rejection– or stromal rejection episodes. Allograft failure occurred in 1 free allograft survival. The survival time was calculated in eye after acute postoperative endophthalmitis with graft melt- months from the date of PK to the date the patient developed ing. On univariate analysis, occurrence of hydrops, duration the first episode of endothelial rejection or failure (clinically of hydrops (.3 months), coexistent ocular allergy, and cor- defined as the loss of transparency of the central cornea for at neal vascularization were found to be significantly associated least 3 months). The secondary outcome measure was best- with endothelial rejection–free allograft survival (Table 2). corrected visual acuity (BCVA), assessed at 6 time points: Multivariate analysis showed a significantly higher risk of

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TABLE 1. Baseline Demographic Characteristics of Eyes That Underwent PK for Keratoconus Characteristics Total, n (%) Hydrops, n (%) No Hydrops, n (%) P Gender 102 32 70 0.67 Male 72 (70.6) 24 (75) 48 (68.6) Female 30 (29.4) 8 (25) 22 (31.4) Age at PK, yr 102 32 70 0.1 #16 47 (46.1) 19 (59.4) 28 (40) .16 55 (53.9) 13 (40.6) 42 (60) Laterality of operated eye 102 32 70 0.5 Right 54 (52.9) 15 (46.9) 39 (55.7) Left 48 (47.1) 17 (53.1) 31 (44.3) Active ocular allergy 102 32 70 ,0.0001 Present 17 (16.7) 13 (40.6) 4 (5.7) VKC 15 (14.7) 12 (37.5) 3 (4.3) Others 2 (1.9) 1(3.1) 1 (1.4) Absent 85 (83.3) 19 (59.4) 66 (94.3) Corneal vascularization 102 32 70 0.12 Present 21 (20.6) 10 (31.3) 11 (15.7) Superﬁcial 20 (19.6) 9 (28.1) 11 (15.7) Deep 1 (0.9) 1 (3.2) 0 (0) Absent 81 (79.4) 22 (68.7) 59 (84.3) Indication for PK 102 32 70 0.14 Poor CL corrected vision 47 (46.1) 21 (65.6) 29 (41.4) CL intolerance 44 (43.1) 9 (28.1) 32 (45.7) Poor CL ﬁtting 11 (10.8) 2 (6.3) 9 (12.9) Donor trephine size, mm 102 32 70 0.56 #8 42 (41.2) 15 (46.9) 27 (38.6) .8 60 (58.8) 17 (53.1) 43 (61.4) Donor ECD, cells/mm2 102 32 70 0.17 2150–2499 17 (16.7) 2 (6.3) 15 (21.4) 2500–3000 65 (63.7) 25 (78.1) 40 (57.1) .3000 20 (19.6) 5 (16.6) 15 (21.4)

CL, contact lens; ECD, endothelial cell density; VKC, vernal keratoconjunctivitis. Values in bold indicate statistically significant results. endothelial rejection episodes in eyes with longer duration of ceftazidime (2.25 mg) and vancomycin (1 g). The vitreous on corneal hydrops (hazard ratio, 6.1; 95% confidence intervals, culture showed significant growth of Streptococcus pneumo- 1.4–27.4; P = 0.019) and coexistent ocular allergy (hazard niae. One year postoperatively, the patient had a clear graft ratio 8.5; 95% confidence intervals, 1.6–45.3; P = 0.012). with BCVA of 20/40. Loose sutures were seen in 16 eyes (15.7%), all within 12 months of PK. Five of these eyes fi Secondary Outcome (4.9%) developed peripheral graft in ltrates caused by The visual outcomes after PK are provided in Table 3. coagulase-negative Staphylococcus species. Complete resolu- At all follow-up visits, more than 90% of patients had BCVA tion of infection and scarring was seen in all 5 eyes with intensive application of fortified cefazolin (5%) eye drops. of better than 20/40. Astigmatism was 4.3 ± 2.6 diopters (D), fi 3.4 ± 1.6 D, 3 ± 1.2 D, 2.8 ± 1.2 D, 2.6 ± 0.9 D, and 2.3 ± Visually signi cant posterior subcapsular cataract developed in 7 eyes (6.8%), and all patients underwent uneventful 0.8 D at 1 years and 2, 3, 4, 5, and 10 years, respectively. fi Corneal topography-guided selective removal of tight sutures phacoemulsi cation with posterior chamber intraocular lens was successful in treating patients with high postoperative implantation. None of the 102 eyes showed an increase in astigmatism, and no patients developed keratectasia or needed intraocular pressure or needed antiglaucoma medications additional surgical interventions. during the entire study period.

Complications Histopathology Findings One patient presented with acute postoperative endoph- All specimens showed epithelial hyperplasia, fragmen- thalmitis with graft inﬁltrate and melting, 5 days after PK. tation of the Bowman layer with variable scarring, and Immediate therapeutic PK with pars plana vitrectomy were thinning of the corneal stroma; these features were consistent performed along with intraocular injection of 0.1 mL each of with a clinical diagnosis of keratoconus. DM and endothelium

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TABLE 2. Endothelial Rejection–Free Allograft Survival Rates in Different Subgroups 5 Years After PK for Keratoconus Endothelial Rejection–Free Graft Signiﬁcance Rejection/ Survival at 5 (Log Rank Factor Total Failure Years ± SE (%) Test) Previous episode of 0.043 hydrops Present 32 5 82.6 ± 7 Absent 70 3 98 ± 2 Age at PK, yr 0.63 #16 47 3 95 ± 4 .16 55 5 91.1 ± 4 Duration of hydrops, 0.045 mo* 0 to 3 76 3 98.3 ± 2 .3 26 5 70.5 ± 11 Donor corneal size. mm 0.76 #8 42 3 93.7 ± 4 .8 60 5 92.4 ± 4 Ocular allergy 0.0001 Absent 85 3 97.3 ± 2 Present 17 5 58.5 ± 2 Vascularization 0.0003 Absent 81 3 97.3 ± 2 Present 21 5 62.4 ± 2 Postoperative suture- 0.06 related problems (loose sutures and/or suture inﬁltrates) Absent 86 5 95.9 ± 2 Present 16 3 78.1 ± 11

*Duration was considered 0 for cases without hydrops. SE, standard error. FIGURE 1. Kaplan–Meier survival curves showing endothelial Values in bold indicate statistically significant results. rejection–free graft survival in eyes undergoing PK for keratoconus. A, The survival rate for all 102 eyes was 98% ± 0.01% at 1 year, 92.9% ± 0.03% at 5 years, and 87.3% ± 0.05% at DM and relayering of a thin periodic acid-Schiff–positive 10 years. B, Comparison between 32 eyes with hydrops and membrane, suggestive of the healing process after hydrops. 70 eyes without hydrops showing that there was a significant difference in the endothelial rejection–free survival rate between these 2 groups (log rank test; P = 0.04). DISCUSSION Keratoconus is a noninflammatory corneal pathology, were normal in eyes without a clinical diagnosis of resolved which makes it immunologically ideal for a successful PK. Tuft hydrops. A single DM break was identified in all 32 speci- et al3 hypothesized that this immune privilege is compromised mens with resolved hydrops, but interestingly, the appearance in eyes developing corneal hydrops because of the associated of DM was different in cases that had received C3F8 from the ocular allergy and peripheral corneal vascularization, leading to ones that had not. In post-C3F8 cases, the broken ends of DM a greater risk of developing allograft rejection episodes after were rolled or folded at one end and flat at the other end, both PK. However, this hypothesis could not be validated in a sub- ends being attached to or buried in the posterior corneal sequent study by Akova et al.4 Our study aimed to reevaluate stroma (Fig. 2). In non–C3F8-treated cases, 2 patterns were the controversial association between corneal hydrops and sub- seen: (1) detachment of one end of DM, whereas the other sequent allograft rejection episodes and allograft survival. We end was seen lying rolled or flat against the posterior stroma found that keratoconic eyes with prolonged duration of corneal (Fig. 3A) or (2) rolling of both ends of DM with attachment to hydrops and/or coexistent ocular allergy were more prone to the posterior corneal stroma (Fig. 3B). Interestingly, folding developing endothelial rejection episodes after PK. However, or burial of DM in the corneal stroma was a feature seen endothelial rejection episodes were rare, medically reversible, exclusively in 7 post-C3F8 cases (87.5%), suggestive of the and did not lead to allograft failure. The visual outcomes of PK pressure tamponade by the gas bubble. All 32 cases showed in eyes with keratoconus, irrespective of corneal hydrops, were endothelial cell migration between the 2 broken ends of excellent and stable throughout the duration of the study.

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follow up, 2 years) noted a much higher rejection episode rate of TABLE 3. Visual and Refractive Outcomes 1, 2, 3, 4, and 5 21% and 31%, respectively. Whether the proportion of cases Years After PK for Keratoconus with hydrops or ocular allergy was higher in the latter 2 studies Hydrops, No Hydrops, is not known. Surprisingly, we did not note any cases with Characteristic n(%) n(%) P (x2 test) epithelial or stromal rejection episodes, which may have been 1 Year 32 70 inadvertently missed had they occurred between scheduled fol- BCVA . 20/40 29 (90.6) 63 (90) 0.97 low-up visits or before episodes of endothelial rejection. Astigmatism . 6 D 3 (12.5) 7 (10) 0.79 Because ocular allergy is known to be associated with 2 Years 29 57 both corneal hydrops2,3 and endothelial rejection episodes BCVA . 20/40 27 (93.1) 54 (94.7) 0.85 after PK,19 it can potentially confound the association be- Astigmatism . 6 D 0 1 (5.3) 0.73 tween the latter 2 variables. To address this issue, we per- 3 Years 24 50 formed a multivariate analysis, which revealed that both BCVA . 20/40 22 (91.6) 48 (96) 0.82 ocular allergy and duration of corneal hydrops were indepen- Astigmatism . 6D 0 0 NA dent risk factors for the development of endothelial rejection 4 Years 22 45 episodes. However, all endothelial rejection episodes were BCVA . 20/40 21 (95.4) 44 (97.7) 0.85 reversed with appropriate medical therapy, and none of the Astigmatism . 6D 0 0 NA eyes developed allograft failure after rejection. In fact, com- 5 Years 20 44 pared with endothelial rejection, nonimmunological causes BCVA . 20/40 20 (100) 42 (95.4) 0.85 account for a significant proportion of allograft failures Astigmatism . 6D 0 0 NA (42.8%–100%) seen after PK in keratoconus.3–10 10 Years 4 9 The histopathology of corneas with resolved hydrops BCVA . 20/40 4 (100) 9 (100) NA has been described earlier.20,21 However, to our knowledge, Astigmatism . 6D 0 0 NA this is the first study to report the histopathology of resolved NA, not applicable. hydrops after intracameral gas injections. The unique findings in post-C3F8 corneas were greater attachment of DM to the posterior stroma and burial of the rolled or folded DM in Although the reported incidence of endothelial rejection the stroma, both of which seem to be compression effects episodes after PK in keratoconus varies widely from 3.6% to of the gas bubble on the DM. Separation between the split 31%, allograft survival at 5 to 12 years has been consistently ends of DM shows that despite C3F8, end-to-end reapprox- reported to be greater than 90%.3–18 Occurrence of endothelial imation of the DM was not possible because of the elastic rejection episodes in our series (6.8%, 102 eyes; mean follow-up, coiling and retraction of DM after rupture. There are concerns 5.5 years) was similar to that noted by Lim et al5 (4%, 93 eyes; about the safety of intracameral gases on the endothelium,22,23 mean follow-up, 3.83 years), Pramanik et al6 (3.6%, 112 eyes, but at least on histopathology, we did not find any signs of 7 mean follow-up, 13.8 years), and Fukuoka et al (9.6%, 125 endothelial attenuation in eyes that received C3F8. eyes; mean follow-up, 15.3 years). Sharif and Casey8 (100 eyes; Recently, 3 different surgical techniques of deep anterior mean follow up of 6.1 years) and Olson et al9 (93 eyes; mean lamellar keratoplasty (DALK) have been described for eyes

FIGURE 2. Photomicrographs of periodic acid-Schiff–stained sections of corneal buttons obtained during PK. A, Corneal specimen from case 3 showing a break in the DM (black arrows, ·20), one end of which is ﬂat and the other end is folded and buried into the stroma. B, C, Varying patterns of rolling, folding, and burial of the broken ends of the DM were seen in eyes that received intracameral gas (·100).

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hydrops, allograft failure was rare and the visual outcomes of PK in the long run were excellent. Patients at a higher risk for endothelial rejection episodes must be educated about its symptoms and about the importance of early reporting to the ophthalmologist once the symptoms develop. Although we cannot prevent endothelial rejection episodes, allograft failure because of rejection can certainly be successfully treated.

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Risk factors for graft failure in basement membrane, which is likely to give way easily, penetrating keratoplasty. Acta Ophthalmol Scand. 1996;74:584–588. 15. Ing JJ, Ing HH, Nelson LR, et al. Ten-year postoperative results of especially if a big-bubble is attempted. Leaving behind a sliver – of the posterior stroma, as described by Das et al24 and Chew penetrating keratoplasty. Ophthalmology. 1998;105:1855 1865. 25 16. Dandona L, Ragu K, Janarthanan M, et al. Indications for penetrating et al, may be advisable to prevent an inadvertent perforation. keratoplasty in India. Indian J Ophthalmol. 1997;45:163–168. Early suture removal and discontinuation of topical steroids 17. Thompson RW Jr, Price MO, Bowers PJ, et al. Long-term graft survival after DALK can help in avoiding loose suture–related graft after penetrating keratoplasty. Ophthalmology. 2003;110:1396–1402. infiltrates and steroid-induced cataracts, which were the most 18. Inoue K, Amano S, Oshika T, et al. Risk factors for corneal graft failure and rejection in penetrating keratoplasty. Acta Ophthalmol Scand. 2001; common complications after PK in this study. 79:251–255. The limitations of this study are inherent to its retro- 19. Yildiz EH, Erdurmus M, Hammersmith KM, et al. Comparative study of spective design. In our previous study, we found that acute graft rejection in keratoconus patients with and without self-reported corneal hydrops occurs in 3% of eyes with keratoconus, of atopy. Cornea. 2009;28:846–850. 2 20. Shaw EL. Pathophysiology and treatment of corneal hydrops. Ophthal- which only 20% require PK for visual rehabilitation. In view mic Surg. 1976;7:33–37. of the rarity of acute corneal hydrops, the infrequent need for 21. Stone DL, Kenyon KR, Stark WJ. Ultrastructure of keratoconus PK in resolved corneal hydrops, and the low rate of allograft with healed hydrops. Am J Ophthalmol. 1976;82:450–458. rejection/failure in keratoconus, a retrospective approach was 22. Green K, Cheeks L, Stewart DA, et al. Intraocular gas effects on corneal – considered appropriate. Multiple surgeons were involved in endothelial permeability. Lens Eye Toxic Res. 1992;9:85 91. 23. Foulks GN, de Juan E, Hatchell DL, et al. The effect of perfluoropropane this study, and it does not include long-term data on endothelial on the cornea in rabbits and cats. Arch Ophthalmol. 1987;105:256–259. cell count, morphology, or corneal topography. 24. Das S, Dua N, Ramamurthy B. Deep lamellar keratoplasty in keratoconus In conclusion, we studied the long-term endothelial with healed hydrops. Cornea. 2007;26:1156–1157. rejection–free allograft survival after PK in eyes with kerato- 25. Chew AC, Mehta JS, Tan DT. Deep lamellar keratoplasty after resolution of hydrops in keratoconus. Cornea. 2011;30:454–459. conus. We found that despite higher chances of endothelial 26. Ramamurthi S, Ramaesh K. Surgical management of healed hydrops: rejection episodes in eyes with prior corneal hydrops, espe- a novel modification of deep anterior lamellar keratoplasty. Cornea. cially those with active ocular allergy and longer duration of 2011;30:180–183.

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