Current indications and surgical approaches to corneal transplants at the University of Toronto: A clinical-pathological study

Trends in keratoplasty from central and northern India. Part II: Types of keratoplasty

PURPOSE

To report the types of keratoplasty and analyze trends over a period of two decades in central and northern India.

METHODS

This was a retrospective review of eye bank registries of six tertiary eye care centers located in central and north India from 2005 to 2021. The indications and various keratoplasty procedures were compared between 2005-2012 and 2013-2021 to analyze the trend.

RESULTS

A total of 13,223 corneal grafts were performed, of which therapeutic penetrating keratoplasty (TPK) (5719, 43.3%) was the most common procedure, followed by optical penetrating keratoplasty (OPK) (5528, 41.8%), Descemet stripping endothelial keratoplasty (DSEK) (1279, 9.7%), deep anterior lamellar keratoplasty (DALK) (376, 2.8%), Descemet membrane endothelial keratoplasty (DMEK) (215, 1.6%), patch grafts (75, 0.6%), and keratoprostheses (31, 0.2%). Overall, OPK procedures decreased (-14.1%, P < 0.001), but TPK (+3.1%, P < 0.019), DSEK (+7.1%, P < 0.001), and DMEK (+1.9%, P < 0.001) procedures increased. Although there was an increasing trend in the use of DALK (+0.8%, P < 0.083) and keratoprostheses (+0.3%, P = 0.074) procedures, the trends were not statistically significant.

CONCLUSION

In keeping with worldwide trends, an increasing trend in lamellar keratoplasties was observed in central and northern India during the past decade. The trend was significant for DSEK. However, as corneal ulcers and scars were the major indications for keratoplasty, TPK and OPK remained the most common procedures.

Role of corneal collagen cross-linking in bullous keratopathy: A systematic review

Corneal cross-linking (CXL), a corneal strengthening procedure, is known to alter anterior stroma swelling behavior and is one of the treatment modalities of bullous keratopathy (BK). There are multiple studies published on the role of CXL in the treatment of BK. These articles had heterogeneous study population, different protocols used, and variable conclusions. This systematic review aimed to determine the role of CXL in the treatment of BK. The primary outcomes considered were changes in central corneal thickness (CCT) after 1, 3, and 6 months of CXL. The secondary outcome measures were changes in visual acuity, corneal clarity, subjective symptoms, and complications after CXL. We included randomized control trials (RCTs), observational and interventional studies, and case series with reports of more than 10 cases in this review. In RCTs, the mean pre-CXL CCT (794.0 ± 178.5 μm) in the intervention group (n = 37), decreased at 1 month (750.9 ± 154.3 μm) followed by a subsequent increase, but this difference was not significant during the 6-month follow-up (P- value 0.28, 0.82, and 0.82 at 1, 3, and 6 months, respectively). In noncomparative clinical studies (n = 188), the mean pre-CXL CCT (794.0 ± 178.5 μm) decreased at 1 month (710.9 ± 127.2 μm, P < 0.0001). Seven of the 11 articles included in the review reported no significant improvement in vision with CXL. The initial improvement in corneal clarity and clinical symptoms was not sustained. Current evidence suggests that CXL has short-term efficacy in the treatment of BK. More RCTs with high-quality evidence are needed.

Early Visibility of Cellular Aggregates and Changes in Central Corneal Thickness as Predictors of Successful Corneal Endothelial Cell Injection Therapy

(1) Background: Cell injection therapy is an emerging treatment for bullous keratopathy (BK). Anterior segment optical coherence tomography (AS-OCT) imaging allows the high-resolution assessment of the anterior chamber. Our study aimed to investigate the predictive value of the visibility of cellular aggregates for corneal deturgescence in an animal model of bullous keratopathy. (2) Methods: Cell injections of corneal endothelial cells were performed in 45 eyes in a rabbit model of BK. AS-OCT imaging and central corneal thickness (CCT) measurement were performed at baseline and on day 1, day 4, day 7 and day 14 following cell injection. A logistic regression was modelled to predict successful corneal deturgescence and its failure with cell aggregate visibility and CCT. Receiver-operating characteristic (ROC) curves were plotted, and areas under the curve (AUC) calculated for each time point in these models. (3) Results: Cellular aggregates were identified on days 1, 4, 7 and 14 in 86.7%, 39.5%, 20.0% and 4.4% of eyes, respectively. The positive predictive value of cellular aggregate visibility for successful corneal deturgescence was 71.8%, 64.7%, 66.7% and 100.0% at each time point, respectively. Using logistic regression modelling, the visibility of cellular aggregates on day 1 appeared to increase the likelihood of successful corneal deturgescence, but this did not reach statistical significance. An increase in pachymetry, however, resulted in a small but statistically significant decreased likelihood of success, with an odds ratio of 0.996 for days 1 (95% CI 0.993-1.000), 2 (95% CI 0.993-0.999) and 14 (95% CI 0.994-0.998) and an odds ratio of 0.994 (95% CI 0.991-0.998) for day 7. The ROC curves were plotted, and the AUC values were 0.72 (95% CI 0.55-0.89), 0.80 (95% CI 0. 62-0.98), 0.86 (95% CI 0.71-1.00) and 0.90 (95% CI 0.80-0.99) for days 1, 4, 7 and 14, respectively. (4) Conclusions: Logistic regression modelling of cell aggregate visibility and CCT was predictive of successful corneal endothelial cell injection therapy.

An Overview of Corneal Transplantation in the Past Decade

The cornea is a transparent avascular structure located in the front of the eye that refracts light entering the eyes and also serves as a barrier between the outside world and the internal contents of the eye. Like every other body part, the cornea may suffer insult from trauma, infection, and inflammation. In the case of trauma, a prior infection that left a scar, or conditions such as keratoconus that warrant the removal of all or part of the cornea (keratoplasty), it is important to use healthy donor corneal tissues and cells that can replace the damaged cornea. The types of cornea transplant techniques employed currently include: penetrating keratoplasty, endothelial keratoplasty (EK), and artificial cornea transplant. Postoperative failure acutely or after years can result after a cornea transplant and may require a repeat transplant. This minireview briefly examines the various types of corneal transplant methodologies, indications, contraindications, presurgical protocols, sources of cornea transplant material, wound healing after surgery complications, co-morbidities, and the effect of COVID-19 in corneal transplant surgery.

A Novel Murine Model of Endothelial Keratoplasty

PURPOSE

The purpose of this study was to establish a murine model of endothelial keratoplasty.

METHODS

Endothelial keratoplasty (EK) was performed using C57BL/6 donor and BALB/c recipient mice. The central endothelium and Descemet membrane were removed from the recipient cornea, and a 1.5-mm posterior lamellar donor graft was made adherent to the recipient cornea with a small amount of viscoelastic. Mice were followed through slitlamp microscopy postoperatively, and OCT was used to assess the cornea and anterior chamber and measure central corneal thickness. Histology and immunohistochemistry were performed to confirm graft adherence and endothelial cell morphology.

RESULTS

Successfully attached EK grafts were visualized in all transplanted animals. Histology and immunostaining confirmed proper graft orientation and adherence, as well as the presence of donor endothelium on transplanted grafts. We observed maximal corneal edema in all animals at day 1 postoperatively which gradually subsided. EK graft survival was 97% at 8 weeks.

CONCLUSIONS

In this study, we describe a novel murine model for EK which we anticipate will enable detailed investigation into the cellular and molecular mechanisms involved in EK pathobiology.

Development of a Nomogram to Predict Graft Survival After Descemet Stripping Endothelial Keratoplasty

BACKGROUND/PURPOSE

The purpose of this study was to analyze Descemet stripping endothelial keratoplasty (DSEK) outcomes and develop a nomogram to compute the probability of 3- and 5-year DSEK graft survival based on risk factors.

STUDY DESIGN/METHODS

The medical records of 794 DSEK procedures between January 1, 2008, and August 1, 2019, were retrospectively reviewed to identify 37 variables. We also evaluated for the presence of corneal graft failure, defined as irreversible and visually significant graft edema, haze, or scarring. Variables were assessed by multivariable Cox models, and a nomogram was created to predict the probability of 3- and 5-year graft survival.

RESULTS

Graft failure occurred in 80 transplants (10.1%). The strongest risk factors for graft failure included graft detachment [hazard ratio (HR) = 4.46; P < 0.001], prior glaucoma surgery (HR = 3.14; P = 0.001), and glaucoma (HR = 2.23; P = 0.018). A preoperative diagnosis of Fuchs dystrophy was associated with a decreased risk of graft failure (HR = 0.47; P = 0.005) compared with secondary corneal edema. Our nomogram has a concordance index of 0.75 (95% confidence interval, 0.69 to 0.81), which indicates that it may predict the probability of graft survival at 3 and 5 years with reasonable accuracy. We also analyzed graft rejection, which occurred in 39 cases (4.9%). The single risk factor found to be significantly associated with graft rejection was prior glaucoma surgery (HR = 2.87; P = 0.008).

CONCLUSIONS

Our nomogram may accurately predict DSEK graft survival after 3 and 5 years based on 4 variables. This nomogram will empower surgeons to share useful data with patients and improve collective clinical decision-making.

Peripheral blood immune cell profiling of acute corneal transplant rejection

Acute rejection (AR) of corneal transplants (CT) has a profound effect on subsequent graft survival but detailed immunological studies in human CT recipients are lacking. In this multi-site, cross-sectional study, clinical details and blood samples were collected from adults with clinically diagnosed AR of full-thickness (FT)-CT (n = 35) and posterior lamellar (PL)-CT (n = 21) along with Stable CT recipients (n = 177) and adults with non-transplanted corneal disease (n = 40). For those with AR, additional samples were collected 3 months later. Immune cell analysis was performed by whole-genome microarrays (whole blood) and high-dimensional multi-color flow cytometry (peripheral blood mononuclear cells). For both, no activation signature was identified within the B cell and T cell repertoire at the time of AR diagnosis. Nonetheless, in FT- but not PL-CT recipients, AR was associated with differences in B cell maturity and regulatory CD4⁺ T cell frequency compared to stable allografts. These data suggest that circulating B cell and T cell subpopulations may provide insights into the regulation of anti-donor immune response in human CT recipients with differing AR risk. Our results suggest that, in contrast to solid organ transplants, genetic or cellular assays of peripheral blood are unlikely to be clinically exploitable for prediction or diagnosis of AR.

Descemet Membrane Endothelial Transfer (DMET) in Pseudophakic Bullous Keratopathy After DSEK-A Case Report and Review of Literature

PURPOSE

The purpose of this study was to report a Descemet membrane endothelial transfer (DMET) in a patient with pseudophakic bullous keratopathy (PBK) who developed graft dislocation after manual Descemet stripping endothelial keratoplasty.

METHODS

A 60-year-old man presented with defective vision in the left eye; after Descemet stripping endothelial keratoplasty, graft dislocation was noted 1 month after surgery.

RESULTS

Corneal clarity was improving slowly over 3 months without any secondary surgical intervention. The mechanism of DMET and the review of literature were enunciated.

CONCLUSIONS

DMET occurs commonly in eyes with Fuch endothelial dystrophy and rarely in patients with PBK. The mechanism of DMET in PBK probably occurs because of migration of the donor endothelial cells from partially attached Descemet stripping endothelial keratoplasty grafts to the host stroma, in contrast to Fuch endothelial dystrophy, where the endothelial cells from the periphery migrate to the center. Hence, waiting for spontaneous corneal clarity is pivotal because of DMET even in patients with PBK for at least 3 months.

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.

Feasibility and Outcomes of Corneal Transplantation Performed at Rural Centers: An Extension of the Pyramidal Model of Enhanced Eye Care at Rural Outreach

PURPOSE

The aim of this study was to report on the feasibility of setting up a system of corneal transplants at rural outreach centers and report the outcomes of the first 111 cases.

METHODS

Retrospective analysis of the outcomes of corneal transplantation performed on patients with optical indications between March 2016 and September 2019 at 4 secondary (rural) centers. The centers are a part of a network in the pyramidal model developed by L V Prasad Eye Institute. The graft clarity and best-corrected visual acuity (BCVA) at 1-year follow-up were analyzed.

RESULTS

Of the 111 patients, 34.23% underwent penetrating keratoplasty and 65.77% endothelial keratoplasty. The mean age was 59.4 ± 15.0 (range-17-86 years); 47.75% were men and 52.25% were women. The indications for surgery were bullous keratopathy (54.05%), corneal scar/adherent leukoma (23.42%), and repeat grafts (13.51%). At the end of 1 year, 69.37% grafts remained clear. Factors associated with graft failure included poor socioeconomic status and graft infiltrate in both univariate and multivariate analyses. Surgical technique of endothelial keratoplasty was associated with failure on multivariate analysis only. Of the 77 eyes with clear corneal grafts at 1 year, the preoperative mean logMAR BCVA was 1.91 ± 0.06, which improved to 0.90 ± 0.08 postoperatively. Overall, 84.4% had preoperative BCVA of <3/60. Postoperatively, 40% had BCVA of 6/18 or better.

CONCLUSIONS

Our study showed that close to 70% grafts remained clear at 1 year. Graft failure was associated with poor socioeconomic status and graft infiltrates. This study established a viable model for delivery of corneal transplant surgery and care in a rural setup.

Visual Outcome of Combined Descemet Stripping Endothelial Keratoplasty and Sutured Scleral Fixated Intraocular Lens in Endothelial Decompensation with Coexistent Aphakia or Intra Ocular Lens Subluxation

Purpose To elucidate visual outcome of patients after combined Descemet stripping endothelial keratoplasty (DSEK) with scleral fixated intra ocular lens (SFIOL) implantation in patients of endothelial decompensation with coexistent aphakia or lens subluxation.

Materials and Methods A prospective interventional study of combined DSEK with sutured SFIOL in the patients who have undergone surgery at our center over 6-month follow-up period. Preoperative visual acuity and slit lamp findings were documented. Postoperative follow-up was done at days 1, 3, and 7 subsequently, months 1 and 3, and thereafter monthly till the sixth month.

Results Mean age of the patients was 60.47 years. Six patients had aphakic bullous keratopathy, while 11 patients had pseudophakic bullous keratopathy with subluxated posterior chamber IOL (PCIOL). Preoperative visual acuity ranged from hand movements close to face (LogMar 2.4) with accurate projection of rays to 1/60 (LogMar 2) due to existing corneal edema and aphakia. Postoperatively uncorrected visual acuity at 6 months improved up to 6/36 (LogMar 0.8) in all cases. There was gradual improvement in corneal clarity and compactness during the follow-up. A good donor tissue endothelial count and an adequate IOP control were vital prognostic factors for the successful outcome.

Conclusion This novel surgical merger reduces the complications of lenticule dislocation into vitreous and repeated surgeries and shows results akin to when performed in a staged manner.

Changing Indications for Corneal Transplantations in Southern Taiwan From 2008 to 2018

OBJECTIVES

To investigate the changing indications for corneal transplantations in southern Taiwan from 2008 to 2018 and compare the results with those of other previous studies.

METHODS

We retrospectively reviewed the records of patients who underwent corneal transplantations from January 2008 to December 2018 at Kaohsiung Veterans General Hospital. The patients' age, sex, indication for corneal transplantation, and the surgical technique were recorded and analyzed.

RESULTS

In total, 336 patients (421 eyes) were included in our study from January 1, 2008, to December 31, 2018. The mean age was 63.6±15.3 years; 371 penetrating keratoplasty (88.1%), 35 deep anterior lamellar keratoplasty (8.3%), and 15 Descemet-stripping automated endothelial keratoplasty (3.6%) were performed. The leading indication for corneal transplantation was regraft (n=103, 24.5%), followed by bullous keratopathy (n=82, 19.5%), corneal scar and opacity (n=79, 18.8%), keratitis (n=59, 14.0%), corneal dystrophy (n=58, 13.8%), other indications (n=26, 6.2%), and keratoconus (n=14, 3.3%).

CONCLUSION

The indications for corneal transplantations changed with time in Taiwan. Regraft was the leading indication, but there was a decreasing trend over time. The proportion of bullous keratopathy increased significantly over the past decade and is the second most common indication, similar to the most developed countries. Both corneal scar and opacity, and keratitis showed a decreasing trend of occurrence compared with a previous study in Taiwan. The proportion of keratoconus remained low, making it the least common indication for corneal transplantation.

Demographic and clinical profile, surgical outcome, and quality of life in patients who underwent bilateral lamellar corneal grafts

Purpose:

Lamellar corneal grafts have revolutionized the management of corneal blindness by replacing only the disease specific corneal layers. To the best of our knowledge, there is no study in literature describing the outcomes of bilateral lamellar keratoplasty in the Indian population. The aim of this work was to study the demographic profile, surgical outcomes, and quality of life in patients who underwent bilateral lamellar keratoplasty and to assess the correlation between these three.

Methods:

An observational cross-sectional study was conducted on 47 patients who underwent bilateral deep anterior lamellar keratoplasty (DALK) (n = 31) or descemet stripping automated endothelial keratoplasty (DSAEK) (n = 16) with a minimum follow-up of 6 months after the second surgery. Demographic parameters were collected by interview, surgical outcomes by clinical examination, and quality of life by a questionnaire.

Results:

A total of 47 patients were evaluated, women 42.56%, (n = 20) and men 57.44% (n = 27) with 38.3% being in 18–30 years age group and 23.4% above 60 years; 17.02% patients had a good socioeconomic status (score >60) and 61.70% had poorer socioeconomic status (score <50). Quality of life score (VR-QoL) was ≥50 in 82.9% patients and ≥70 in 14.89%. No significant association existed between VR-QoL scores and demographic factors. However, statistically significant association existed between VR-QoL and age of patient (P < 0.05), postoperative vision (P ≤ 0.05), and contrast sensitivity (P ≤ 0.01).

Conclusion:

Bilateral lamellar corneal grafts provide satisfactory visual outcomes compatible with day-to-day functioning. VR-QoL has a direct correlation to the age, visual acuity, contrast sensitivity, and inverse correlation with lenticule thickness in DSAEK and residual bed thickness in DALK.

Corneal transplantation activity in Catalonia, Spain, from 2011 to 2018: Evolution of indications and surgical techniques

Purpose

To report corneal transplant activity carried out in Catalonia (Spain) and the evolving indications for keratoplasty over an 8-year period.

Methods

Annual reports from the Catalan Transplant Organization, Spain, on corneal graft indications and techniques from 2011 to 2018 were reviewed.

Results

A total of 9457 keratoplasties were performed in Catalonia, from January 2011 to December 2018. The most frequent indications were bullous keratopathy (BK; 20.5%), Fuchs endothelial dystrophy (FED; 17.9%), re-graft (13.7%), and keratoconus (11.3%). Penetrating keratoplasty (PKP) accounted for 63.4% of all performed keratoplasties. Since the introduction of eye bank precut tissue for Descemet stripping automated endothelial keratoplasty (DSAEK) in 2013 and for Descemet membrane endothelial keratoplasty (DMEK) in 2017 the number of endothelial keratoplasties has drastically increased. An increasing trend of posterior lamellar techniques over the total of keratoplasties was found (p<0.001). Endothelial keratoplasties for different endothelial diseases indications (BK, FED, and re-graft), also showed and increasing trend (p<0.001). DMEK is the technique with the highest increase (statistically significantly different from linearity) over other endothelial keratoplasties in FED (p<0.001) but not in BK (p = 0.67) or re-grafts (p = 0.067).

Conclusion

Endothelial diseases represented the top indication for keratoplasty over the 8-year period. PKP is still the most used technique in Catalonia, but endothelial keratoplasties and especially DMEK showed a significant increasing trend over the last years. This is congruent with the main rationale nowadays for keratoplasties: to customize and transplant as less tissue as possible. Therefore, the availability of precut tissue could have definitely enforced such approach.

Endophthalmitis After Descemet Stripping Endothelial Keratoplasty: Microbiological Yield and Visual Outcomes

PURPOSE

To describe the clinical presentation, management, and visual outcomes of 6 eyes with endophthalmitis after Descemet stripping endothelial keratoplasty (DSEK).

DESIGN

Retrospective case series.

METHODS

Setting: Tertiary, academic eye center. StudyPopulation: Individuals developing endophthalmitis after DSEK at the Duke Eye Center from January 1, 2009, to January 1, 2018, with at least 6 months of follow-up. ObservationProcedure: Retrospective chart review. OutcomeMeasures: Diagnostic procedures, microbiological yield, and visual outcomes.

RESULTS

Six eyes of 6 patients were identified. Mean time from surgery to presentation was 51 days (range, 4-137 days). Dense vitreous opacities were present in all cases. Five of 6 cases (83%) had culture-proven infectious endophthalmitis (2 Candida glabrata, 2 coagulase-negative Staphylococcus, 1 Streptococcus pneumoniae). Aqueous tap yielded positive culture in 2 of 2 cases with adequate sample (100%); needle vitreous tap yielded positive culture in 0 of 3 cases. One eye underwent vitrectomy on presentation, and 3 eyes (50%) underwent subsequent vitrectomy for persistent endophthalmitis after a mean of 37 days. Mean pre-endophthalmitis visual acuity (VA) was 20/64; mean VA at 6 months was 20/2069 (average 15 ETDRS lines lost). VA at 6 months was light perception or no light perception in 3 of 6 cases (50%). One eye underwent enucleation at 6 months, and 1 eye became phthisical 1 year after endophthalmitis.

CONCLUSIONS

DSEK-related endophthalmitis may lead to severe vision loss, even with prompt and appropriate treatment. Aqueous tap had a higher culture yield than needle vitreous tap in our series.

Fuchs endothelial corneal dystrophy: The vicious cycle of Fuchs pathogenesis

Fuchs endothelial corneal dystrophy (FECD) is the most common primary corneal endothelial dystrophy and the leading indication for corneal transplantation worldwide. FECD is characterized by the progressive decline of corneal endothelial cells (CECs) and the formation of extracellular matrix (ECM) excrescences in Descemet's membrane (DM), called guttae, that lead to corneal edema and loss of vision. FECD typically manifests in the fifth decades of life and has a greater incidence in women. FECD is a complex and heterogeneous genetic disease where interaction between genetic and environmental factors results in cellular apoptosis and aberrant ECM deposition. In this review, we will discuss a complex interplay of genetic, epigenetic, and exogenous factors in inciting oxidative stress, auto(mito)phagy, unfolded protein response, and mitochondrial dysfunction during CEC degeneration. Specifically, we explore the factors that influence cellular fate to undergo apoptosis, senescence, and endothelial-to-mesenchymal transition. These findings will highlight the importance of abnormal CEC-DM interactions in triggering the vicious cycle of FECD pathogenesis. We will also review clinical characteristics, diagnostic tools, and current medical and surgical management options for FECD patients. These new paradigms in FECD pathogenesis present an opportunity to develop novel therapeutics for the treatment of FECD.

Endothelial corneal transplants: indications, clinical profile and surgical outcomes in a tertiary care hospital

Background

Endothelial keratoplasties have become the surgical procedure of choice over full thickness penetrating keratoplasty for corneal decompensation because of endothelial dysfunction.

Methods

A retrospective data review was performed from February 2016 to April 2017 for all the patients who underwent endothelial keratoplasty in a tertiary care center for Indian Armed Forces.

Results

A total of 161 corneal transplants were performed; endothelial keratoplasties accounted for 34 (21.1%) transplants. Most common indication was pseudophakic/aphakic bullous keratopathy followed by Ahmed glaucoma valve-related corneal decompensation and Fuchs' corneal dystrophy, respectively. Mean preoperative corneal thickness was 845.96 ± 106.9 microns. Mean lenticule thickness was 131.55 ± 42.47 microns with microkeratome for descemet stripping automated endothelial keratoplasty (DSAEK) and 174 ± 70.4 microns manually for descemet stripping endothelial keratoplasty (DSEK). Mean preoperative best-corrected visual acuity (BCVA) was 1.65 LogMAR (Snellen equivalent in meters 2/60 approx) which significantly improved to 0.82 LogMAR (Snellen equivalent in meters 6/36 approx) after surgery. In the DSAEK group, BCVA improved from 1.61 to 0.7 LogMAR, whereas in the DSEK group, the visual acuity improved from 1.7 to 0.94 LogMAR at one-month postoperative period. Postoperatively, two patients had graft detachment and had to undergo repeat DSAEK.

Conclusion

Study results suggest the similar trends in our tertiary care hospital as in other most advanced ophthalmic centers around the world for adoption of newer techniques of lamellar corneal transplants and their outcomes.

Corneal transplantation in the modern era

Corneal blindness is one of the major causes of reversible blindness, which can be managed with transplantation of a healthy donor cornea. It is the most successful organ transplantation in the human body as cornea is devoid of vasculature, minimizing the risk of graft rejection. The first successful transplant was performed by Zirm, and since then, corneal transplantation has seen significant evolution. It has been possible because of the relentless efforts by researchers and the increase in knowledge about corneal anatomy, improvement in instruments and advancements in technology. Keratoplasty has come a long way since the initial surgeries wherein the whole cornea was replaced to the present day where only the selective diseased layer can be replaced. These newer procedures maintain structural integrity and avoid catastrophic complications associated with open globe surgery. Corneal transplantation procedures are broadly classified as full-thickness penetrating keratoplasty and partial lamellar corneal surgeries which include anterior lamellar keratoplasty [sperficial anterior lamellar keratoplasty (SALK), automated lamellar therapeutic keratoplasty (ALTK) and deep anterior lamellar keratoplasty (DALK)] and posterior lamellar keratoplasty [Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK)] broadly.

A 27-Year Report from the Central Eye Bank of Iran

Purpose

To report the 27-year statistical data from the Central Eye Bank of Iran (CEBI) and its activity.

Methods

All CEBI records regarding procured eyes, tissue utilizations, corneal transplants per capita, and indications for keratoplasty from 1991 to 2017 were analyzed.

Results

In total, 115,743 whole eyes were donated during the 27-year period. Out of the 114,169 eyes donated between 1994 and 2017, 95,314 eyes were distributed for transplantation, and 95,057 corneas were actually transplanted. The mean annual rate of corneal transplants per capita was 55.10 - 6 ± 27.10 - 6 . Although penetrating keratoplasty (PKP, 70%) was the most common technique of corneal transplantation during the study period, it exhibited a decreasing trend between 2006 and 2017 (P = 0.048). It was in contrast to Descemet stripping automated endothelial keratoplasty (DSAEK) that demonstrated an increasing trend during the same period (P < 0.001). Keratoconus (KCN, 39.70%) was the most leading indication for keratoplasty over the last three decades followed by bullous keratopathy (BK, 18.5%), corneal scar and opacities (15.7%), and graft failure (GF, 7.5%), with an increasing trend for BK, GF, and KCN. A majority of scleral tissues (83.7%) were utilized for orbital implant protection.

Conclusion

An increasing trend in the number of procured eyes was observed over the past 27 years in Iran. The most leading indications for corneal transplantation were KCN and BK. While PKP was the most common keratoplasty technique, DSAEK showed an increasing trend over the last 12 years.

Proposed risk factors for failure of transplanted eye bank-prepared descemet stripping automated endothelial keratoplasty tissues

To investigate the possible risk factors for failure of transplanted eye bank-prepared Descemet stripping automated endothelial keratoplasty (DSAEK) tissues. In a retrospective study between March 2011 and March 2019, all the failed DSAEK cases (131 cases) reported to the Central Eye Bank of Iran were compared with a surgeon-matched successful DSAEK group (control, 126 cases) in terms of the donor, DSAEK tissue, and recipient characteristics. Univariate analysis indicated that the DSAEK tissue preparation from excised corneoscleral tissues (OR 2.17; P = 0.026) and donor conjunctival hyperemia (OR 1.62; P = 0.042) were more common in the re-DSAEK group than in the controls. Other donor and recipient characteristics as well as other DSAEK tissue criteria were not significantly different between the re-DSAEK and control groups. DSAEK lenticules in both re-DSAEK and control groups demonstrated symmetric contours. Subgroup analyses in the re-DSAEK group revealed a higher rate of surgeons' low to moderate experience in comparison to those of high experience (P < 0.001). Additionally, failed DSAEK was observed more commonly in donors aged over 50 years than among those under 30 years (P < 0.001). Our study showed that DSAEK tissues prepared from excised corneoscleral tissues and from donors with conjunctival hyperemia were associated with higher rates of re-DSAEK due to failed DSAEK. An increasing trend of re-DSAEK was observed with shorter surgeons' experience and more advanced donor's age.

Lymphatic vessels identified in failed corneal transplants with neovascularisation

BACKGROUND

Corneal transplant failure with neovascularisation is a leading indication for full-thickness grafts in patients. Lymphangiogenesis is implicated in the pathology of graft failure, and here we systematically evaluate failed human corneal transplants with neovascularisation for the presence of lymphatic vessels.

METHODS

Nine failed grafts with neovascularisation, based on H&E staining with subsequent immunoperoxidase staining for CD31, a blood vessel marker, were selected. Lymphatics were investigated by immunohistochemical and immunofluorescence approaches using podoplanin as a lymphatic marker. In two of nine cases, fluorescence in situ hybridisation (FISH) was used for detection of lymphatic mRNAs including podoplanin, VEGFR-3 and LYVE-1. All immunofluorescence and FISH samples were compared with positive and negative controls and visualised by confocal microscopy.

RESULTS

Corneal neovascularisation was established in all cases by H&E and further confirmed by CD31 immunoreactive profiles. Immunohistochemistry for the podoplanin antibody was positive in all cases and showed morphologies ranging from distinct luminal structures to elongated profiles. Simultaneous immunofluorescence using CD31 and podoplanin showed lymphatic vessels distinct from blood vessels. Podoplanin immunofluorescence was noted in seven of nine cases and revealed clear lumina of varying sizes, in addition to lumen-like and elongated profiles. The presence of lymphatic mRNA was confirmed by FISH studies using a combination of at least two of podoplanin, VEGFR-3 and LYVE-1 mRNAs.

CONCLUSIONS

The consistent finding of lymphatic vessels in failed grafts with neovascularisation implicates them in the pathogenesis of corneal transplant failure, and points to the lymphatics as a potential new therapeutic target.

Indications and techniques of corneal transplantation in a referral center in Colombia, South America (2012-2016)

PURPOSE

To describe the indications and techniques of corneal grafting in a tertiary institution in a middle-sized city in Colombia.

METHODS

A retrospective review of surgical reports and medical records of patients undergoing keratoplasty from January 2012 to December of 2016.

RESULTS

A total of 346 eyes from 316 patients were included. The first three indications for keratoplasty were: bullous keratopathy (BK) with 46.2% of the cases, active infectious keratitis (22.3%) and the group of corneal dystrophies and degenerations, including Fuchs' endothelial dystrophy (9%). Keratoconus was in the sixth place (4.9%). 73.3% of the procedures were penetrating keratoplasties (n = 255), 21.7% posterior lamellar (n = 75) and 3.5% anterior lamellar (n = 12). While in 2012, 25 cases of endothelial grafts were performed, only 13 were done in 2016.

CONCLUSIONS

BK was the first cause of keratoplasty with almost half of the cases, and keratoconus was relegated to sixth place with less than 5%. In comparison, in a study from eye banks from the US, BK was the second and keratoconus was the third indication for corneal grafts. The frequency of endothelial lamellar techniques in our institution decreased from 2012 to 2016. This could have been related to both the long time that the patients had to be on a waiting list, which made them unsuitable candidates for this technique, due to stromal fibrosis, and to the fact that surgeons of our institution had less experience with posterior endothelial grafting than with penetrating keratoplasties.

Deep anterior lamellar keratoplasty: A surgeon's guide

Purpose

To review and highlight important practical aspects of deep anterior lamellar keratoplasty (DALK) surgery and provide some useful tips for surgeons wishing to convert to this procedure from the conventional penetrating keratoplasty (PK) technique.

Methods

In this narrative review, the procedure of DALK is described in detail. Important pre, intra, and postoperative considerations are discussed with illustrative examples for better understanding. A comprehensive literature review was conducted in PubMed/Medline from January 1995 to July 2017 to identify original studies in English language regarding DALK. The primary endpoint of this review was the narrative description of surgical steps for DALK, its pitfalls, and management of common intraoperative complications.

Results

A standard DALK procedure can be successfully performed taking into consideration factors such as age, ophthalmic co-morbidities, status of the crystalline lens, retina, and intraocular pressure. Careful trephination and dissection of the host cornea employing appropriate technique (such as big bubble technique, manual dissection, visco-dissection, etc.) suitable for the specific case is important to achieve good postoperative outcomes. Prompt identification of intraoperative complications such as double bubble, micro and macroperforations, etc. are vital to change the management strategies.

Conclusion

Although there is a steep learning curve for DALK procedure, considering details and having insight into the management of intraoperative issues facilitates learning and reduces complication rates.