Deep anterior lamellar keratoplasty versus penetrating keratoplasty for macular corneal dystrophy: a randomized trial

Management of Stromal Corneal Dystrophies; Review of the Literature with a Focus on Phototherapeutic Keratectomy and Keratoplasty

Corneal dystrophies are a group of non-inflammatory inherited disorders of the cornea. This review considers treatment options for epithelial-stromal and stromal corneal dystrophies: namely Reis–Bücklers, Thiel–Behnke, lattice, Avellino, granular, macular and Schnyder corneal dystrophies. Where there is visual reduction, treatment options may include either phototherapeutic keratectomy (PTK) or corneal transplantation. Due to the anterior location of the deposits in Reis-Bücklers and Thiel–Behnke dystrophies, PTK is considered the treatment of choice. For lattice, Avellino, granular and macular corneal dystrophies, PTK provides temporary visual improvement; however, with recurrences, repeat PTK or a corneal transplant would be needed. For Schnyder dystrophy, should treatment be required, PTK may be the preferred option due to the potential for recurrence of the disease in corneal transplantation. This review discusses the literature and evidence base for the treatment of corneal dystrophies in terms of visual outcomes and recurrence rate.

Complications in deep anterior lamellar keratoplasty – A retrospective cross sectional interventional analysis in a large series

AIM

To analyse complications in patients managed with deep anterior lamellar keratoplasty (DALK) for diseases of anterior corneal stroma.

MATERIALS AND METHODS

This was a retrospective analysis of all the patients who underwent DALK in a tertiary care center in South India from 2010 to 2021. A total of 484 eyes in 378 patients were included in the study. Patients who underwent DALK for advanced keratoconus, keratoconus with Bowman's membrane scar, healed hydrops, macular corneal opacity, macular corneal dystrophy, granular corneal dystrophy, spheroidal degeneration, pellucid marginal degeneration, post-LASIK ectasia, descemetocele, postcollagen cross-linking aborted melt and dense scar, and postradial keratotomy were included in the study. The patients were followed up for 17.6±9.4 months(1-10years).

RESULTS

Complications noted in the surgery were intraoperatively Descemet's membrane perforation in 32 eyes (6.6%), postoperatively secondary glaucoma in 16 eyes (3.31%), cataract in 7 eyes (1.45%), suture-related complications in 5 eyes (1.03%), graft rejection in 3 eyes (0.61%), traumatic dehiscence in 2 eyes (0.41%), filamentary keratitis in 2 eyes (0.41%), interface infiltrate in 1 eye (0.21%), and recurrence of disease in 4 eyes (8.77%) out of 57 eyes with corneal dystrophy.

CONCLUSION

DALK as an alternative to penetrating keratoplasty for anterior corneal stromal diseases has proven to be better time and again. It has become an automatic choice for diseases of anterior cornea requiring keratoplasty. Complications occurring at any stage of surgery can be identified and managed effectively resulting in optimal outcome. This article compiles complications post DALK.

Complications in deep anterior lamellar keratoplasty - A retrospective interventional analysis in a large series

Purpose

To analyze the complications in patients managed with deep anterior lamellar keratoplasty (DALK) for diseases of the anterior corneal stroma.

Methods

This is a retrospective analysis of all the patients who underwent DALK in a tertiary care center in South India from 2010 to 2020. A total of 474 eyes in 373 patients were included in the study. Patients who underwent DALK for advanced keratoconus, keratoconus with Bowman's membrane scar, healed hydrops, macular corneal opacity, macular corneal dystrophy, granular corneal dystrophy, spheroidal degeneration, pellucid marginal degeneration, post-laser-assisted in situ keratomileusis ectasia, descematocele, post-collagen cross-linking aborted melt and dense scar, and post-radial keratotomy were included in the study. The patients were followed up for 17.2 +/- 9.2 months (1-9 years).

Results

Complications noted in the surgery were intra-operatively Descemet's membrane perforation in 31 eyes (6.54%), post-operatively secondary glaucoma in 16 eyes (3.37%), cataract in seven eyes (1.47%), suture-related complications in five eyes (1.05%), graft rejection in three eyes (0.63%), traumatic dehiscence in two eyes (0.42%), filamentary keratitis in two eyes (0.42%), interface infiltrate in one eye (0.21%), and recurrence of disease in four eyes (7.14%) out of 57 eyes with corneal dystrophy.

Conclusion

DALK as an alternative to penetrating keratoplasty for anterior corneal stromal diseases. It has become an automatic choice for diseases of the anterior cornea requiring keratoplasty. Complications can occur at any stage of surgery; however, if identified and managed early, they can result in optimal outcome.

Update on Pediatric Corneal Diseases and Keratoplasty

Managing pediatric corneal disorders is challenging as the prognosis of pediatric keratoplasty depends on several factors. Advancements in the genetic basis of congenital corneal diseases and investigations in congenital corneal conditions provide a better understanding of pediatric corneal conditions. Surgeons performing keratoplasty in children now have a choice of various techniques. Evolving surgical techniques of anterior lamellar and endothelial keratoplasties has expanded the management interventions in these pediatric corneal morbidity conditions; however, considerable concerns still exist in association with corneal transplantation in infants and children. Outcomes in pediatric keratoplasty depend upon the preoperative indications, the timing of surgical intervention, intraoperative and postoperative factors including the patient/care givers' compliance. Factors such as low scleral rigidity, higher rate of graft failure, need for frequent examinations under anesthesia, and difficulty in optimal visual acuity assessment still remain a considerable challenge in pediatric scenarios. In children, deprivation amblyopia as a result of the corneal opacification can adversely affect visual development, causing dense amblyopia. Outcomes to surgical interventions for management of corneal opacification in children is further compromised by the pre-existing amblyopia apart from the concerns of refractive outcome of the graft. Graft rejection, graft infection, amblyopia, and glaucoma continue to be serious concerns. In recent years both anterior and posterior lamellar keratoplasty techniques are being increasingly performed in pediatric eyes, which offer advantages in the form of lower risk of graft rejection. The timing of surgery, careful case selection, cautious intraoperative approach, and optimal postoperative management can improve the anatomical and functional outcome in difficult cases.

Current Perspectives on Corneal Transplantation

Disease of the cornea is the third leading cause of blindness worldwide. Corneal graft surgery is one of the most successful forms of solid organ transplantations in humans, with ever-increasing developments in surgical technique. To date, approximately 4504 corneal transplants are performed in the United Kingdom each year. While full thickness transplantation was the most commonly performed keratoplasty over the last few decades, selective lamellar transplantation of the diseased layers of the cornea has been universally adopted. This comprehensive review aims to provide an updated synthesis on different types of corneal transplantations, their treatment outcomes, and the associated complications of each procedure in both adult and paediatric population. In addition, we also present an up-to-date summary of the emerging therapeutic approaches that have the potential to reduce the demand for donor-dependent keratoplasty.

Does Storage Time Affect the Outcomes of Split Corneal Transplantation to Reduce Corneal Donor Shortage? A Retrospective Study

Split cornea transplantation can reduce the shortage of donor corneas. Therefore, this study aimed to evaluate the effect of split graft storage time on the outcomes of split corneal transplantation through Descemet membrane endothelial keratoplasty (DMEK) and deep anterior lamellar keratoplasty (DALK) surgeries. Split corneal transplantation was performed in 80 eyes using 41 donor corneas. The mean before and after splitting storage times and total storage times were recorded. Donor corneal buttons and split grafts were stored in short-term solution at 4°C. In both surgeries (DMEK and DALK), donor corneas were divided into groups depending on their storage times. Mean postoperative 12th month best corrected visual acuity (BCVA), endothelial cell density (ECD), endothelial cell loss (ECL), central corneal thickness (CCT), refractive spherical equivalent (RSE), refractive astigmatism, and complication rates were compared among the groups. Correlation between storage times and 1-year BCVA, ECL, and complication rates were assessed. Clinical outcomes of the groups 1 year after the surgeries were also compared. DALK and DMEK were performed in 41 and 39 eyes, respectively. Storage times were not correlated with 1-year DMEK outcomes and only weakly correlated with post-DALK ECD, ECL, and RSE values. Except for CCT in those that underwent DALK, the outcomes of DMEK and DALK surgeries with stored and non-stored split grafts were not significantly different (P = .02). The storage times of donor corneas and split grafts do not have any impact on outcomes.

Medium-Term Clinical Outcomes of Deep Anterior Lamellar Keratoplasty versus Penetrating Keratoplasty for Macular Corneal Dystrophy

Purpose

To compare the postoperative outcomes of deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PKP) for macular corneal dystrophy (MCD).

Design

Single-center, retrospective, interventional case series.

Methods

A chart review was performed of 100 patients (157 eyes) who underwent primary DALK (DALK group) and PKP (PKP group) for histopathologically confirmed MCD for whom at least 12 months of follow-up were available. Between-group comparisons were performed of visual acuity (VA), graft survival, and postoperative complications.

Results

There were 22 eyes in the DALK group and 135 in the PKP group. Postoperative best-corrected visual acuity (BCVA) of 20/40 or better was achieved in 90.9% of the DALK group and 76.3% of the PKP group (P=0.12). At last visit, graft survival was 95.5% (21 eyes) and 91.1% (123 eyes) in DALK and PKP groups, respectively (P=0.69, Log rank test). Corneal graft rejection episodes occurred in 1 (4.5%) DALK graft and 19 (14.1%) PKP grafts. Five of the 19 graft rejections in the PKP group were irreversible. Microbial keratitis and cataract occurred in 6 (4.5%) and 15 (11.1%) PKP eyes. One (4.5%) eye in the DALK group had cataract and none of the DALK cases developed microbial keratitis. Clinically significant recurrence was observed in 4 (2.9%) PKP eyes and 1 (4.5%) DALK eye (P=0.69), respectively.

Conclusion

DALK is a viable option for MCD without Descemet membrane involvement. DALK had comparable medium-term visual and survival outcomes to PKP. DALK has the advantage of lower open sky intraoperative complications and lower graft rejection episodes.

Macular Corneal Dystrophy: An Updated Review

Macular Corneal Dystrophy is an autosomal recessive form of corneal dystrophy due to a mutation in CHST6 gene, which results in abnormal proteoglycan synthesis. There is accumulation of abnormal glycosaminoglycans in the corneal stroma and endothelium. The deposition results in progressive loss of corneal transparency and visual acuity. The histopathology shows characteristic alcian blue positive deposits. Management in the cases with visual loss requires keratoplasty either full thickness or lamellar. The decision about the ideal type of keratoplasty depends on age and pre-operative clinical features. Although prognosis after keratoplasty is good, recurrences can occur. Future research should be targeted towards gene therapy in this condition.

Impairment of the autophagy-lysosomal pathway and activation of pyroptosis in macular corneal dystrophy

Macular corneal dystrophy (MCD) is ascribed to mutations in the carbohydrate sulfotransferase (CHST6) gene affecting keratan sulfate (KS) hydrophilicity and causing non-sulfated KS to precipitate in keratocytes and the corneal stroma. We investigated roles for inflammatory responses in MCD pathogenesis by examining the lysosomal-autophagy pathway and activation of pyroptosis in MCD keratocytes. Normal and lesioned keratocytes were obtained from MCD patients undergoing corneal transplantation. The keratocytes were subjected to gene sequencing, RT-PCR, western blotting, transmission electron microscopy, histological staining, induction and inhibition assays of autophagy and pyroptosis, CCK-8 and LysoTracker Green DND-26 labeling, and flow cytometry. A novel homozygous MCD mutation was identified in a family from Northeast China; the mutation was distinguished by cytoplasmic vacuolation, cell membrane disruption, electron dense deposits, and deposition of a band of Periodic acid-Schiff and Alcian blue-positive material in the keratocytes and stroma layer. KS protein levels were decreased, expression of p62 and LC3-II proteins was enhanced, cathepsin D expression was declined and the LysoTracker Green DND-26 signal was dramatically reduced in MCD keratocytes. Bafilomycin-A1 treatment significantly increased caspase-1 and Pro-IL-1β expression in normal and MCD keratocytes. Nod-like receptors pyrins-3 (NLRP3), caspase-1, Pro-IL-1β, and IL-1β levels were pronouncedly elevated in cells exposed to H2O2. Ac-YVAD-CMK treatment reversed this expression in normal and MCD keratocytes. Suppression of the autophagic degradation of non-sulfated KS by impaired autophagic flux in MCD keratocytes triggers pyroptosis. Amelioration of impaired autophagy and restraint of pyroptosis may, therefore, have therapeutic efficacy in the treatment of MCD.

Bilateral phototherapeutic keratectomy for corneal macular dystrophy in an adolescent: case report and review of the literature

PURPOSE

Phototherapeutic keratectomy (PTK) with 193-nm excimer laser is a safe and effective procedure for the treatment of superficial corneal pathology. We aimed to review the use of PTK for the treatment of corneal macular dystrophy (MCD).

METHODS

Case report and literature review.

RESULTS

A 16-year-old boy presented to an ophthalmologist with a 4-year history of reduced vision, glare and photophobia in his left eye. He was diagnosed with corneal macular dystrophy and underwent sequencing of the CHST6 gene. Left excimer PTK with mitomycin C was performed. He remained relapse free until 18 months post procedure when his visual acuity declined and the stroma appeared more "milky". He underwent a penetrating keratoplasty in his left eye 24 month following the initial PTK.

CONCLUSION

Phototherapeutic keratectomy is an effective means of visual restoration in patients with macular corneal dystrophy and may delay penetrating keratoplasty. Patients should be counselled regarding the high risk of recurrence. This is the first reported case of a CHST6 gene positive patient with MCD that was treated with phototherapeutic keratoplasty.

High-risk Corneal Transplantation: Recent Developments and Future Possibilities

Human corneal transplantation (keratoplasty) is typically considered to have superior short- and long-term outcomes and lower requirement for immunosuppression compared to solid organ transplants because of the inherent immune privilege and tolerogenic mechanisms associated with the anterior segment of the eye. However, in a substantial proportion of corneal transplants, the rates of acute rejection and/or graft failure are comparable to or greater than those of the commonly transplanted solid organs. Critically, while registry data and observational studies have helped to identify factors that are associated with increased risk of corneal transplant failure, the extent to which these risk factors operate through enhancing immune-mediated rejection is less clear. In this overview, we summarize a range of important recent clinical and basic insights related to high-risk corneal transplantation, the factors associated with graft failure, and the immunological basis of corneal allograft rejection. We highlight critical research areas from which continued progress is likely to drive improvements in the long-term survival of high-risk corneal transplants. These include further development and clinical testing of predictive risk scores and assays; greater use of multicenter clinical trials to optimize immunosuppressive therapy in high-risk recipients and robust clinical translation of novel, mechanistically-targeted immunomodulatory and regenerative therapies that are emerging from basic science laboratories. We also emphasize the relative lack of knowledge regarding transplant outcomes for infection-related corneal diseases that are common in the developing world and the potential for greater cross-pollination and synergy between corneal and solid organ transplant research communities.

Deep anterior lamellar keratoplasty outcomes in macular and granular corneal dystrophy - A comparative cross-sectional study

Purpose

To compare the functional and anatomical outcomes (in terms of graft uptake and rejection/failure) of deep anterior lamellar keratoplasty (DALK) in stromal corneal dystrophy (macular and granular).

Methods

Sixteen eyes with macular corneal dystrophy (MCD; group A) and 10 eyes with granular corneal dystrophy (GCD; group B) underwent successful DALK by big bubble technique or layer-by-layer dissection.

Results

Both groups showed significant improvement in their best-corrected visual acuity postoperatively (postoperative P value in MCD and GCD was 0.00001 and 0.0008, respectively) with no statistically significant differences between the two groups (P = 0.77) at 1 year. Postoperative endothelial count did not drop significantly in group A (MCD, P= 0.1553). Only in seven eyes preoperative endothelial count could be obtained (due to dense stromal corneal opacity), but there was a significant endothelial count difference between preoperative and postoperative count in group B (GCD, P= 0.0405) at the end of 1 year postoperatively which could be because of age and stage of disease (advanced granular dystrophy) and also because of small sample size of GCD compared with MCD. Intergroup comparison between the two groups showed no statistically significant difference (P = 0.6353) with good postoperative outcome in both groups.

Conclusion

DALK can be successfully done in both groups and results are comparable. However, long-term outcomes on a large scale need to be further evaluated.

Changing Trends in Penetrating Keratoplasty Indications between 2011 and 2018 - Histopathology of 2123 Corneal Buttons in a Single Center in Germany

Purpose: To analyse the changing trends in penetrating keratoplasty indications between January 2011 and December 2018, at the Department of Ophthalmology, Saarland University Medical Center, Homburg/Saar, Germany. Patients and Methods: This is a retrospective review of 2123 corneal buttons of 1776 patients (1993 eyes, 56.0% males, age at the time of surgery 57.6 ± 18.7 years), who underwent penetrating keratoplasty (PKP) between January 2011 and December 2018. The classification was performed based on histological analysis and using the priority scheme of Brady et al., supplemented by a group of "failed endothelial keratoplasty grafts". Our groups were the following: pseudophakic or aphakic bullous keratopathy, regraft, failed endothelial keratoplasty graft, acute necrotizing and ulcerative keratitis, keratoconus, Fuchs' dystrophy, corneal dystrophy other than Fuchs', corneal scars and other diagnoses. Results: Between 2011 and 2018, keratoconus was the leading indication for PKP in 455 (21.5%) cases, followed by acute necrotizing and ulcerative keratitis in 384 (18.1%), regraft in 367 (17.3%), corneal scars in 350 (16.5%), pseudophakic or aphakic bullous keratopathy in 225 (10.6%), Fuchs' dystrophy in 194 (9.1%), other diagnoses in 64 (3.0%), corneal dystrophy other than Fuchs' in 52 (2.4%), and failed endothelial keratoplasty graft in 32 (1.5%) cases. Conclusions: With the introduction of posterior lamellar keratoplasty, keratoconus remains the leading PKP indication in our center with excimer laser-trephination on a routine basis. A trend towards increasing numbers can be observed regarding acute necrotizing and ulcerative keratitis patients and regrafts. However, the incidence of Fuchs' dystrophy decreased dramatically within PKP patients, with the introduction of posterior lamellar keratoplasty.

Nerve Growth Factor Changes and Corneal Nerve Repair after Keratoplasty

SIGNIFICANCE

Measured tear concentration of nerve growth factor is correlated with postoperative corneal reinnervation among patients who undergo keratoplasty. This may be a future therapeutic target for post-keratoplasty corneal nerve regeneration.

PURPOSE

To determine the relationship between changes in the content of nerve growth factor (NGF) in tear fluid and corneal subepithelial nerve regeneration in patients after keratoplasty.

METHODS

In this retrospective study, 30 eyes of 28 patients (15 males, 13 females; mean age 42.8 [range 16–73] years) who underwent primary keratoplasty for the first time were recruited through the clinics of the Department of Ophthalmology, Jilin University affiliated First Hospital, between May and December 2015. All patients underwent a complete ophthalmic examination preoperatively. Tear fluid samples were collected to detect the content of NFG at different time points in the follow-up period (day 1 preoperatively and days 1, 7, 30, and 90 postoperatively) and analyzed correlations between NFG content and age, infective factors, and variables of the surgical procedure as well as with subepithelial nerve repair at 30 and 90 days postoperatively.

RESULTS

The NFG content in tear fluid on day 1 postoperatively was lower than that on the day preceding surgery; however, it was higher than the preoperative value on postoperative days 7, 30, and 90 (F = 5.046, P < 0.05). Further, the NFG content of tear fluid at 30 days postoperatively correlated with the surgical procedure (coefficient = −2.775, P = 0.010); however, no significant correlation was found on postoperative day 1 (coefficient = −1.315, P> 0.05). At all study time points, the NFG content of tear fluid had no correlation with infective factors or age (P> 0.05). Postoperatively, at day 30, small nerve buds were observed in the periphery of the corneal graft in 13 eyes (43.3% of cases) but not in 17 eyes (56.7% of cases), which showed a significant correlation with the NFG content of tear fluid (coefficient = −3.370, P = 0.010). By postoperative day 90, small nerve buds were observed in the periphery of the corneal graft in 24 eyes (80.0% of cases) and showed a significant correlation with the NFG content of tear fluid (coefficient = −2.750, P = 0.006).

CONCLUSIONS

The NFG content in tear fluid increases with the increasing ratio of small nerve buds indicating corneal nerve regeneration. NFG promotes subepithelial nerve regeneration in patients after keratoplasty.

Impact of Corneal Higher-Order Aberrations on Visual Acuity After Deep Anterior Lamellar Keratoplasty in Treating Keratoconus

PURPOSE

To evaluate the incidence of the Descemet membrane (DM) folds after deep anterior lamellar keratoplasty (DALK) in treating keratoconus. We also evaluated the influence of DM folds and corneal higher-order aberrations (HOAs) on visual acuity after DALK.

METHODS

This retrospective study included 89 consecutive eyes of 87 patients who underwent DALK for the treatment of keratoconus at Tokyo Dental College Ichikawa General Hospital from April 2002 to June 2017. The presence or absence of DM folds was determined by slitlamp microscopy. Visual acuity after DALK was compared between the eyes with and without DM folds. Corneal HOAs of the anterior and posterior surfaces and the total cornea were measured by anterior segment optical coherence tomography. Correlations among the presence of DM folds, corneal HOAs, and visual acuity were analyzed.

RESULTS

The Descemet membrane folds developed in 28.1% (25/89) eyes after DALK for the treatment of keratoconus. However, there were no significant differences in postoperative visual acuity between the eyes with and without DM folds at 1, 3, 6, and 12 months (P=0.739, P=0.106, P=0.223, and P=0.186, respectively). The visual acuity at 12 months was significantly correlated with corneal HOAs within a 4-mm diameter (anterior surface: R=0.546, P=0.003; total cornea: R=0.506, P=0.007).

CONCLUSIONS

Larger corneal HOAs, but not the presence of DM folds, were associated with poor visual acuity after DALK. In treating advanced keratoconus with DALK, it is important to minimize postoperative corneal HOAs, although DALK improves visual acuity by reducing HOAs due to keratoconus.

Etiology of Global Corneal Blindness and Current Practices of Corneal Transplantation: A Focused Review

PURPOSE

The purpose of this focused review was to explore the etiologies of corneal blindness worldwide and compare them with the indications and type of keratoplasties (eg, full-thickness penetrating keratoplasty, anterior lamellar keratoplasty, or endothelial keratoplasty) performed.

METHODS

A literature search of the articles published in the top 10 journals (based on the Altmetrics score) relevant to corneal transplantation within the past 20 years was performed to determine how the focus within corneal transplantation has changed over time. These data were compared with the prevalence and etiology of corneal blindness in each respective region worldwide.

RESULTS

The leading etiologies of corneal blindness worldwide are primarily due to anterior corneal pathology with a normal endothelium, and the prevalence is highest in developing countries. In addition, the number and type of corneal transplantations performed globally indicate that current practices are disproportionately skewed in favor of endothelial keratoplasty, which is targeted for the pathology prevalent in developed countries. Despite the large number of individuals who would benefit from anterior lamellar keratoplasty, this technique seems to be infrequently performed.

CONCLUSIONS

Most corneal blindness worldwide is secondary to anterior corneal pathology because of infections and trauma. However, this does not align with the current trends and practices in the field of corneal transplantation. We discuss potential solutions to address the current leading causes of global corneal blindness, including increasing the number of anterior lamellar keratoplasties performed, using long-term preserved corneas by trained surgeons, and improving eye bank handling and distribution of procured tissues.

Primary graft failure after big bubble deep anterior lamellar keratoplasty in macular corneal dystrophy

Macular corneal dystrophy is autosomal recessive dystrophy characterized by deposits of abnormal glycosaminoglycans in stromal lamellae and within endothelial cells. Deep anterior lamellar keratoplasty is successful in the management of this dystrophy. We herein describe three cases of primary graft failure after uneventful big bubble deep anterior lamellar keratoplasty for macular corneal dystrophy.

Avoiding big bubble complications: outcomes of layer-by-layer deep anterior lamellar keratoplasty in children

BACKGROUND/AIMS

To describe the visual and clinical outcomes of manual layer-by-layer deep anterior lamellar keratoplasty (DALK) in a paediatric population.

METHODS

The charts of all children who underwent DALK surgery between January 2007 and January 2015 were reviewed retrospectively. Data collected included preoperative and postoperative spectacle-corrected distance visual acuity (CDVA), intraoperative and postoperative complications including graft rejection and failure. Residual posterior lamellar thickness (RPLT) and endothelial cell density (ECD) were measured in eyes with follow-up longer than 6 months.

RESULTS

Fifty-one eyes of 42 patients were included in the study. The mean patient age at surgery was 11.2±5.2 years and the mean follow-up time was 36.5±23.7 months. The most common indications for surgery were mucopolysaccharidosis (29.4%) and keratoconus (23.5%). Nine eyes (17.6%) had intraoperative microperforation, none of which were converted to penetrating keratoplasty (PKP). Only one eye (2.0%) was converted to PKP. Five eyes (9.8%) had a stromal rejection episode of which one eye failed. Another four eyes (7.8%) experienced graft failure among which three eyes (75%) had infectious keratitis. Three of the five failed grafts had a successful repeat DALK. The average RPLT was 81.9±36.5μm. ECD was significantly lower in the operated eye compared with the normal eye (3096±333 cells/mm² vs 3376±342 cells/mm², n=11, P=0.003). The mean postoperative CDVA was 0.5±0.4 logarithm of the minimum angle of resolution (logMAR) reflecting a gain of 0.3 logMAR (P<0.001).

CONCLUSION

Manual dissection DALK is a safe procedure in children with stromal opacities. Despite successful structural rehabilitation, functional recovery is still suboptimal mostly due to amblyopia.

Endothelial cell loss in penetrating keratoplasty, endothelial keratoplasty, and deep anterior lamellar keratoplasty

PURPOSE:

To compare endothelial cell density (ECD) loss rates in penetrating keratoplasty (PKP), Descemet's stripping automated endothelial keratoplasty (DSAEK), and deep anterior lamellar keratoplasty (DALK).

DESIGN:

Single-center, multiple-surgeon, retrospective cohort study.

MATERIALS AND METHODS:

Patients who received PKP, DSAEK, or DALK from 2009 to 2014 were analyzed (68 vs. 38 vs. 11 patients, respectively). We excluded patients with therapeutic PKP or regraft, infection, endothelial rejection, or uncontrolled glaucoma. Only clear grafts and initial ECD more than 1000 cell/mm² were included in the study. The main outcome was ECD loss rate. The follow-up time period was divided into five subgroups: 0–1.5 months, 1.5–6 months, 6–12 months, 12–24 months, and longer than 24 months.

RESULTS:

Average ECD loss rate (cell/mm²/month) declined in all three groups (PKP group: −561.5, −113.2, −36.6, −31.4, and −53.7; DSAEK group: −686.4, −68.3, −21.8, −14.4, and −5.1; DALK group: −576.5, −68, −23.7, 5.9, and 18.3). Although DSAEK group showed faster ECD loss rate in the early postoperative period, it became slower compared to the PKP group within the postoperative 6^th month and demonstrated significant difference within 2 years. No ECD loss developed in the DALK group after the 1^st postoperative year; this was significantly different from the PKP group.

CONCLUSIONS:

Although ECD loss rate in the DSAEK group was initially larger than that in the PKP group, the DSAEK group possessed better long-term endothelial cell survival rate. The DALK group had a lower ECD loss rate than that of the other groups and maintained a stable ECD at 1 year after surgery.

Novel mutation in the CHST6 gene causes macular corneal dystrophy in a black South African family

BACKGROUND

Macular corneal dystrophy (MCD) is a rare autosomal recessive disorder that is characterized by progressive corneal opacity that starts in early childhood and ultimately progresses to blindness in early adulthood. The aim of this study was to identify the cause of MCD in a black South African family with two affected sisters.

METHODS

A multigenerational South African Sotho-speaking family with type I MCD was studied using whole exome sequencing. Variant filtering to identify the MCD-causal mutation included the disease inheritance pattern, variant minor allele frequency and potential functional impact.

RESULTS

Ophthalmologic evaluation of the cases revealed a typical MCD phenotype and none of the other family members were affected. An average of 127 713 variants per individual was identified following exome sequencing and approximately 1.2 % were not present in any of the investigated public databases. Variant filtering identified a homozygous E71Q mutation in CHST6, a known MCD-causing gene encoding corneal N-acetyl glucosamine-6-O-sulfotransferase. This E71Q mutation results in a non-conservative amino acid change in a highly conserved functional domain of the human CHST6 that is essential for enzyme activity.

CONCLUSION

We identified a novel E71Q mutation in CHST6 as the MCD-causal mutation in a black South African family with type I MCD. This is the first description of MCD in a black Sub-Saharan African family and therefore contributes valuable insights into the genetic aetiology of this disease, while improving genetic counselling for this and potentially other MCD families.

Intraoperative Optical Coherence Tomography for Enhanced Depth Visualization in Deep Anterior Lamellar Keratoplasty From the PIONEER Study

PURPOSE

Deep anterior lamellar keratoplasty (DALK) is a challenging procedure that often results in conversion to penetrating keratoplasty. Preservation of Descemet membrane (DM) relies on indirect visualization of surgical planes. We describe a technique for enhanced visualization of key steps in DALK with intraoperative optical coherence tomography.

METHODS

Using a microscope-mounted spectral domain optical coherence tomography system, high-resolution images of various steps were obtained.

RESULTS

Specifically, images were obtained of the trephination depth and proximity of the cannula tract to DM. Other key steps such as air cannula placement, assessment of the DM position and integrity after attempted big-bubble delivery, and assessment of graft-host apposition were readily visualized. The presence of intrastromal emphysema after air injection decreased visualization of deeper structures.

CONCLUSIONS

Intraoperative optical coherence tomography allows visualization of depth-dependent anatomy and changes from specific surgical interventions during DALK not appreciated with the en face operating microscope view and has the potential to facilitate big-bubble delivery. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT02423161.

Morphometric changes of corneal endothelial cells following intracameral air for micro perforation of the Descemet Membrane during big-bubble deep anterior lamellar keratoplasty

Aim

The aim of this study was to assess the effect of intracameral air on the endothelial cell morphometrics.

Patients and methods

This is a retrospective controlled interventional cohort study of 26 patients (18 males and 8 females) who underwent unilateral deep anterior lamellar keratoplasty (DALK) for moderate keratoconus. The DALK patients were divided into two groups: a treatment group (14), which had micro perforations of the Descemet Membrane (DM) intraoperatively and received intracameral air at the end of the surgery; and an independent control group (12), which had no micro perforation and thus no intracameral air was injected. Postoperative best corrected visual acuity (BCVA), sphere, cylinder, spherical equivalent (SEQ), central corneal thickness, and endothelial cell morphometric features consisted of the endothelial cell density (ECD), polymegathism, and pleomorphism were compared between treatment and control groups.

Results

The mean BCVA was 0.36 ± 0.36 logMAR in the treatment group and 0.17 ± 0.11 logMAR in the control group (p = 0.081), and the mean corneal thickness was 507.86 ± 62.69 μm in the treatment group and 525.67 ± 37.54 μm in the control group air (p = 0.399). Furthermore, the mean sphere was −5.14 ± 4.17D and −1.02 ± 3.29D, the mean cylinder was −3.16 ± 2.20D and −2.88 ± 1.21D, and the mean SEQ was −6.72 ± 4.66D and −2.46 ± 3.14D and in the treatment and control groups respectively (p = 0.011, 0.693, and 0.013). As to morphometric features, the mean ECD was 2176.76 ± 549.18 cell/mm² and 2257.30 ± 436.12 cell/mm² in the treatment and control groups respectively (p = 0.686), and the mean pleomorphism 0.48 ± 0.09 and 0.54 ± 0.10 in the treatment and control groups respectively (p = 0.139). In contrast, the mean polymegathism was 0.37 ± 0.06 and 0.31 ± 0.05 in the treatment and control groups respectively (p = 0.009).

Conclusion

The presence of air inside the anterior chamber for a short term may not cause further endothelial cell loss and can be safely performed to prevent postoperative Descemet Membrane detachment in case of micro perforations.

Aetiology-specific comparison of long-term outcome of deep anterior lamellar keratoplasty for corneal diseases

AIMS

To evaluate the long-term outcome of deep anterior lamellar keratoplasty (DALK) for the treatment of herpetic keratitis, keratoconus, stromal scars and corneal dystrophies.

METHODS

This retrospective consecutive case study includes 275 consecutive eyes of 254 patients who underwent DALK; 35 eyes with herpetic keratitis, 114 eyes with stromal scar, 93 eyes with keratoconus and 67 eyes with corneal dystrophy. Exclusion criteria included therapeutic DALK for the treatment of descemetocele or infectious keratitis, and eyes with limbal stem cell deficiency. Patients were examined at 1, 3 and 6 months, and 1, 3 and 5 years after DALK. Graft survival rate, best corrected visual acuity (BCVA), endothelial cell density (ECD) and postoperative complications were evaluated.

RESULTS

The mean postoperative follow-up duration was 51±41 months. The graft survival rate of all subjects was 96.8% at 1 year, 89.9% at 3 years, 83.5% at 5 years and 74.1% at 10 years. At 6 months, BCVA significantly improved from 1.14±0.54 to 0.22±0.21 in the keratoconus group, from 1.13±0.60 to 0.44±0.54 in the herpes group, from 1.00±0.59 to 0.49±0.38 in the stromal scar group and from 1.04±0.52 to 0.32±0.29 in the corneal dystrophy group (all, p<0.0001). BCVA stabilised after 6 months thereafter up to 5 years. ECD decreased just after DALK and maintained >1000 cell/mm(2) at 5 years in all groups.

CONCLUSIONS

DALK provides good visual acuity with slight ECD decrease over long term in all groups.

Comparison of femtosecond laser-assisted deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus

BACKGROUND

To compare outcomes of femtosecond laser-assisted deep anterior lamellar keratoplasty (FSL-DALK) and penetrating keratoplasty (FSL-PK) for the treatment of keratoconus.

METHODS

Twenty eight eyes underwent FSL-DALK (consisted of 12 eyes in the FSL-DALKa subgroup without baring the Descemet's membrane and 16 eyes in the FSL-DALKb subgroup baring the Descemet's membrane using big-bubble technique) were compared with 12 eyes that underwent FSL-PK for keratoconus. These patients underwent an ophthalmic examination preoperatively and 3, 6, 9, and 12 months postoperatively.

RESULTS

The postoperative BCVA in the FSL-PK group, and the FSL-DALKb subgroup were significantly better than that in the FSL-DALKa subgroup (P < 0.05), whereas no differences were found between the FSL-DALKb subgroup and the FSL-PK group (P > 0.05). There were no significant differences in the mean spherical equivalent (SE) and astigmatism between the FSL-DALK and the FSL-PK groups, nor between the subgroups of FSL-DALK during the follow-up period (P > 0.05). At the last follow-up, the mean endothelial cell loss in the FSL-DALK group (9.12 %) was significantly less than that in the FSL-PK group (20.79 %) (P < 0.001), while there was no difference between the FSL-DALKa (9.15 %) and the FSL-DALKb (9.10 %) subgroups (P = 0.15). The FSL-DALK group seemed to have fewer graft rejections (1/28 cases) than the FSL-PK group (2/12 cases), although Kaplan-Meier curve showed no significant difference between the two groups (P = 0.144).

CONCLUSIONS

In this retrospective study, the results suggested that FSL-DALKb gives better visual outcome, and FSL-DALKb is a better option for keratoconus whose endothelium is not compromised. However, larger and prospective studies are further required.

Clinical outcomes and risk factors for graft failure after deep anterior lamellar keratoplasty and penetrating keratoplasty for macular corneal dystrophy

PURPOSE

The aim of this study was to compare visual acuity, clinical outcomes, complications, and risk factors for graft failure after deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy.

METHODS

Retrospective comparative case series.

RESULTS

The PK group consisted of 109 eyes of 84 patients and the DALK group consisted of 21 eyes of 20 patients. The mean logarithm of the minimum angle of resolution best-corrected visual acuity at 3 and 12 months was 0.5 versus 0.5 (P = 0.285) and 0.4 versus 0.4 (P = 0.67) in the DALK and PK groups, respectively. There was no significant statistical difference in astigmatism and spherical equivalent between the 2 groups at 12 months. In the PK group, graft rejection that was the most common cause of graft failure was seen in 27 eyes (25%), of which 55% occurred within 1 year. In the DALK group, Descemet membrane microperforation occurred in 5 eyes (24%) intraoperatively, and early postoperative Descemet membrane detachment with double anterior chamber occurred in 9 eyes (43%). Kaplan-Meier estimate of graft survival in PK versus DALK groups were 93% versus 80% at 1 year and 78% versus 70% at 4 years, respectively.

CONCLUSIONS

Visual and refractive outcomes are comparable between DALK and PK groups. DALK was superior to PK in its safety against postoperative complications such as endothelial rejection and secondary glaucoma. Graft failure in DALK was mostly associated with either intraoperative or early postoperative complications. DALK is a viable surgical option in cases with macular corneal dystrophy.

A year of cornea in review: 2013

PURPOSE

The goal of this study was to provide an update of significant corneal literature published in 2013.

DESIGN

This study is a systematic literature review.

METHODS

We conducted a systematic review of the English-language literature published from January 1, 2013, to December 31, 2013, using the following PubMed search and Medical Subject Headings terms: cornea transplantation, keratoplasty, Descemet membrane endothelial keratoplasty, Descemet stripping endothelial keratoplasty, cross linking, pre-Descemet's layer, Rho-associated kinase, keratoprosthesis, infectious keratitis, corneal dystrophy, corneal astigmatism, and keratoconus.

RESULTS

This review summarizes relevant and innovative original articles, review articles, and novel techniques from the following journals: American Journal of Ophthalmology, British Journal of Ophthalmology, Cornea, Graefe's Archive for Clinical and Experimental Ophthalmology, Investigative Ophthalmology & Visual Science, JAMA Ophthalmology, Journal of Cataract and Refractive Surgery, Journal of Refractive Surgery, and Ophthalmology. Case reports, abstracts, letters to the Editor, and unpublished work were excluded, as well as articles e-published ahead of print in 2012 that were discussed in the previous review. One hundred twenty-seven articles met the criteria for this review.

CONCLUSIONS

This review summarizes significant cornea-related literature from 2013.