Effect of Six-Month Postoperative Endothelial Cell Density on Graft Survival after Descemet Membrane Endothelial Keratoplasty.

PURPOSE: To analyze if 6-month endothelial cell density (ECD) affects long-term ECD outcome and graft survival 5 years after Descemet membrane endothelial keratoplasty (DMEK) in eyes with Fuchs endothelial corneal dystrophy (FECD). DESIGN: Retrospective cohort study. PARTICIPANTS: A total of 585 DMEK eyes were included. The study group was divided into 4 groups based on 6-month ECD quartiles: group 1 (n = 146) with 313 to 1245 cells/mm2, group 2 (n = 148) with 1246 to 1610 cells/mm2, group 3 (n = 145) with 1611 to 1938 cells/mm2, and group 4 (n = 146) with 1939 to 2760 cells/mm2. Group 1 was further split into subgroups 1a (n = 36) with 6-month ECD of ≤828 cells/mm2, 1b (n = 37) with 829 to 1023 cells/mm2, 1c (n = 37) with 1024 to 1140 cells/mm2, and 1d (n = 36) 1141 to 1245 cells/mm2. METHODS: Descemet membrane endothelial keratoplasty. MAIN OUTCOME MEASURES: Long-term ECD, graft survival, and postoperative complication rates. RESULTS: For group 1, 6-month ECD decreased from 951 (±233) cells/mm2 (n = 146) to 735 (±216) cells/mm2 (n = 99) at 5 years postoperatively. Group 1 graft survival probability was 0.95 (95% confidence interval [CI], 0.91-0.99] at 5 years postoperatively, which was lower than for groups 2 to 4 (P = 0.001). Five-year graft survival in subgroup 1a was 0.79 (95% CI, 0.67-0.94), which was lower than in subgroups 1b to 1d (P = 0.001). Preoperative ECD did not influence graft survival (P = 0.400), and higher 6-month ECD values were associated with lower graft failure rates (hazard ratio, 0.994; 95% CI, 0.99-1.00; P = 0.001). CONCLUSIONS: Six-month ECD is associated with DMEK graft survival. High early cell loss after DMEK negatively affects long-term ECD outcome and graft survival. Grafts in the lowest 6-month ECD subgroup (≤828 cells/mm2) are at higher risk of failure within 5 years after DMEK. To ensure sufficiently high 6-month ECD, preoperative graft quality assessment should be optimized, and cellular stress induced to the graft should be minimized. Additionally, developing therapeutic options for the treatment of low postoperative ECD could further improve DMEK graft longevity.

The influence of preparation and storage time on endothelial cells in Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) grafts in vitro.

Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) has been introduced as a modification of the standard DMEK technique to increase the pool of endothelial grafts. In this study, we evaluated in vitro changes in endothelial cell distribution, viability and morphology of Quarter-DMEK grafts when stored in organ-culture medium. Quarter-DMEK grafts were prepared from 5 corneas and stored in organ-culture medium for 4, 7 and 11 days. Endothelial cell re-distribution was investigated by light microscopy, cell viability by a Calcein-AM assay, and expression of endothelial and non-endothelial markers by immunohistochemistry. Three standard DMEK-grafts were used as controls. After preparation, all Quarter-DMEK grafts showed a band with no viable endothelial cells along the radial cut graft edges [average width 190 (± 20) µm]. Endothelial cell density in the central graft area decreased by 12%, 23% and 26% after 4, 7, and 11 days of storage, respectively. At the same time, empty bands along the cut edges were re-populated and some cells migrated to the stromal side of the Descemet membrane (DM). These cells showed an altered phenotype, as indicated by expression of migration marker CD73 and fibroblast marker αSMA. Majority of migration occurred within the first 4 days of storage. Our data suggest that endothelial cells on Quarter-DMEK grafts re-distribute during organ-culture storage to re-populate preparation-induced empty bands and after re-distribution, cells may show further migration to the stromal DM side during storage.

Clinical outcome of 500 consecutive cases undergoing Descemet's membrane endothelial keratoplasty.

PURPOSE: To evaluate the clinical outcome of 500 consecutive cases after Descemet's membrane endothelial keratoplasty (DMEK) and the effect of technique standardization. DESIGN: Prospective, interventional case series at a tertiary referral center. PARTICIPANTS: A total of 500 eyes of 393 patients who underwent DMEK for Fuchs' endothelial corneal dystrophy, bullous keratopathy, or previous corneal transplant failure. METHODS: Best-corrected visual acuity (BCVA), endothelial cell density (ECD), pachymetry, and intraoperative and postoperative complications were evaluated before and 1, 3, and 6 months after DMEK. MAIN OUTCOME MEASURES: Comparison between 2 groups (group I: cases 1-250, outcome of "early surgeries" during transition to technique standardization; group II: cases 251-500, outcome of "late surgeries" after technique standardization). RESULTS: At 6 months, 75% of eyes reached a BCVA of ≥20/25 (≥0.8), 41% of eyes achieved ≥20/20 (≥1.0), and 13% of eyes achieved ≥20/18 (≥1.2) (n=418) when excluding eyes with ocular comorbidities (n=57). When including all available eyes at 6 months (n=475), 66% of eyes reached a BCVA of ≥20/25 (≥0.8), and 36% of eyes achieved ≥20/20 (≥1.0). Mean ECD decreased by 37% (±18%) to 1600 (±490) cells/mm2 (n=447) at 6 months (P<0.001). Postoperative pachymetry averaged 525 (±46) µm compared with 667 (±92) µm preoperatively (P<0.001). None of these parameters differed among the 2 groups (P>0.05). (Partial) graft detachment presented in 79 eyes (15.8%), and 26 eyes (5.2%) required a secondary surgery within the first 6 months (re-bubbling in 15, secondary keratoplasty in 11). With technique standardization, the postoperative complication rate decreased from 23.2% to 10% (P<0.001) and the rate of secondary surgeries decreased from 6.8% to 3.6% (P=0.10). CONCLUSIONS: In comparison with earlier endothelial keratoplasty techniques, DMEK may consistently give higher visual outcomes and faster visual rehabilitation. When used for the extended spectrum of endothelial pathologies, DMEK proved feasible with a relatively low risk of complications. Technique standardization may have contributed to a lower graft detachment rate and a relatively low secondary intervention rate. As such, DMEK may become the first choice of treatment in corneal endothelial disease.

The role of topical insulin in ocular surface restoration: A review.

Corneal epithelial defects are one of the most common ocular disorders. Restoring corneal integrity is crucial to reduce pain and regain function, but in cases of neurotrophic or desensitized corneas, healing can be significantly delayed. Treating neurotrophic corneas is challenging for ophthalmologists, and surgical intervention is often indicated to manage refractory cases that are unresponsive to medical therapy. Over the last decade, as more expensive therapeutics reach the market, topical insulin has returned to the forefront as an affordable option to improve corneal wound healing. There is still a paucity of data on the use and the efficacy of topical insulin, with no consensus regarding its indications, preparation, or posology. Here we review the literature on topical insulin for corneal and ocular surface pathologies, with a focus on the current evidence, its mechanisms of action, and its safety profile. Additionally, we share our experience in the field and provide a potential framework for future research.

Clinical Outcomes of Repeat Descemet Membrane Endothelial Keratoplasty After Graft Failure.

PURPOSE: To evaluate the clinical outcomes after repeat Descemet membrane endothelial keratoplasty (DMEK) for technical failure (TF) and secondary graft failure (SGF). METHODS: Retrospective analysis of 49 eyes that underwent repeat DMEK either for TF (ie, persistent graft detachment, n = 24) or for SGF (ie, late endothelial graft failure, n = 25). Surgery indications for primary DMEK were Fuchs endothelial corneal dystrophy (FECD, 80%) and bullous keratopathy (BK, 20%). Main outcome measures were best-corrected visual acuity (BCVA), endothelial cell density (ECD), corneal backscattering, pachymetry, and graft survival. Outcomes were compared with an age-matched control group of 49 primary DMEK eyes. RESULTS: Logarithm of the minimum angle of resolution BCVA improved from 0.92 ± 0.6 before to 0.20 ± 0.3 at 1 year after repeat DMEK with better outcomes for eyes with TF than those with SGF (P = 0.046). Donor ECD decreased from 2618 ± 171 cells/mm2 before to 1247 ± 422 cells/mm2 at 1 year postoperatively, with no difference between technical TF and SGF eyes (P > 0.05). One-year BCVA and ECD outcomes were better in the control group than in the repeat DMEK group (P < 0.05). Five-year graft survival probability after repeat DMEK was better for TF than for SGF eyes (100% vs. 75%, P = 0.010) and better for eyes with FECD than BK as primary indication for surgery (92% vs. 65%, P = 0.042). CONCLUSIONS: Repeat DMEK gives acceptable clinical outcomes especially when performed for TF in the early period after primary DMEK. Long-term graft survival probability after repeat DMEK is comparable to primary DMEK for FECD eyes, whereas BK eyes may show an elevated risk to develop graft failure again.

Corneal Guttae After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: The aim of this study was to report on the occurrence of corneal guttae after Descemet membrane endothelial keratoplasty (DMEK). METHODS: In this retrospective case series, 13 eyes of 13 patients who underwent DMEK at 2 tertiary referral centers between 2007 and 2021 (average available follow-up 73 ± 52 months, range 18-174 months) and showed corneal guttae during postoperative examinations were included. Eye bank images were retrospectively reviewed. RESULTS: Occurrence of guttae was observed by specular microscopy in 13 eyes. In 11 cases, presence of guttae was confirmed by confocal microscopy and in 1 case by histology. Five eyes showed an increase in guttae density during the postoperative course. Surgery indications were Fuchs endothelial corneal dystrophy (n = 11), pseudophakic bullous keratopathy (n = 1), and DMEK graft failure after allograft rejection (n = 1); the latter eye had shown no signs of guttae after primary DMEK. Two eyes with guttae required a repeat DMEK due to graft failure. At the last available follow-up, all 11 remaining eyes had clear corneas and 10 eyes had a best-corrected visual acuity of ≥0.9 (decimal). During donor cornea processing in the eye bank, no guttae were observed on the donor tissue. CONCLUSIONS: Corneal guttae can occur after DMEK including in eyes operated for indications other than Fuchs endothelial corneal dystrophy and most likely guttae were present on the donor graft but were not detectable by routine slit-lamp and light microscopy evaluation in the eye bank. Postoperative guttae density varies among patients and especially small isolated guttae do not seem to affect clinical outcomes.

Bowman Layer Onlay Grafting as a Minimally Invasive Treatment for the Most Challenging Cases in Keratoconus.

PURPOSE: To analyze the clinical outcomes after Bowman layer (BL) onlay grafting for the treatment of progressive, advanced keratoconus. DESIGN: Prospective, interventional case series. METHODS: Twenty-one eyes underwent BL onlay grafting. After removing the epithelium, a single or double BL graft was "stretched" onto the corneal surface, allowed to dry-in, and a soft bandage lens was placed until the graft was re-epithelialized. Best spectacle- and/or best contact lens-corrected visual acuity (BSCVA/BCLVA), corneal tomography, and postoperative complication rates were analyzed for the total group and 2 subgroups (group 1: preoperative maximum keratometry [Kmax] <69 diopters [D; n = 7); group 2: preoperative Kmax ≥69 D [n = 14]). Follow-up ranged from 6 to 36 months (mean 21 ± 11 months). RESULTS: All 21 surgeries were uneventful. Overall, Kmax changed from 76 ± 12 D preoperatively to 72 ± 9 D at 6 to 36 months postoperatively (P = .015). Kmax decreased by 6 D in group 2 (P = .002) but did not change in group 1. Average BSCVA remained stable for group 1 and improved from preoperatively 0.8 ± 0.4 to 0.4 ± 0.2 logarithm of the minimum angle of resolution postoperatively in group 2 (P = .032); BCLVA remained stable (P > .05). Within the first postoperative weeks, 2 eyes required BL graft repositioning after inadvertent bandage lens removal and 4 eyes underwent BL retransplantation for incomplete re-epithelialization. One eye underwent BL regrafting 12 months postoperatively after traumatic corneal erosion. All eyes showed a completely re-epithelialized graft at the last available follow-up. CONCLUSIONS: BL onlay grafting is a completely extraocular, minimally invasive surgical technique, providing up to -6 D of corneal flattening in eyes with advanced progressive keratoconus, allowing for continued (scleral) contact lens wear and therefore preserving the BCLVA.

Dyes for Eyes™: hydrodynamics, biocompatibility and efficacy of 'heavy' (dual) dyes for chromovitrectomy.

As epiretinal membranes (ERMs), the internal limiting membrane (ILM) and the vitreous cortex are essentially transparent tissues, or translucent structures, nontraumatic removal may be challenging in various types of macular surgery. Vital dyes stain these thin tissues, thus allowing for better visualization of these structures during vitrectomy and selective 'membrane peeling' from the underlying retina. To avoid swirling of the dye within the fluid-filled vitreous cavity, and to better target the dye onto the macula, a fluid-air exchange is commonly performed. However, this may jeopardize visualization of the macula during peeling due to clouding of the posterior lens capsule, and may lead to postoperative visual field defects. Recently, a new dye solution for staining the ERM and ILM simultaneously has been developed that circumvents the need for fluid-air exchange, i.e. MembraneBlue-Dual™. This paper will focus on the hydrodynamics and biocompatibility of this 'heavy' dual dye and its efficacy for staining of the ILM and/or ERMs during posterior segment surgery in a multicenter clinical setting.

Early and late-onset cell migration from peripheral corneal endothelium.

In this study we describe peripheral corneal endothelial cell migration in vitro in the absence and presence of a ROCK-inhibitor. For this study, 21 corneal endothelial graft rims, with attached trabecular meshwork (TM), were prepared from Descemet membrane-endothelial cell sheets by 6.5 mm trepanation. For the initial proof-of-concept, 7 outer graft rims were cultured in a thermo-reversible hydrogel matrix for up to 47 days. To assess the effect of a ROCK-inhibitor, 14 paired outer rims were cultured either with or without ROCK-inhibitor for up to 46 days. At the end of culture, tissue was retrieved from the hydrogel matrix and examined for cell viability and expression of different endothelial cell markers (ZO-1, Na+/K+-ATPase, NCAM, glypican, and vimentin). All cultured rims remained viable and displayed either single regions (n = 5/21) or collective areas (n = 16/21) of cell migration, regardless of the presence or absence of ROCK-inhibition. Migration started after 4±2 days and continued for at least 29 days. The presence of ROCK-inhibitor seemed to contribute to a more regular cell morphology of migrating cells. In addition, 7 outer rims demonstrated a phenotypically distinct late-onset but fast-growing cell population emerging from the area close to the limbus. These cells emerged after 3 weeks of culture and appeared less differentiated compared to other areas of migration. Immunostaining showed that migrated cells maintained the expression patterns of endothelial cell markers. In conclusion, we observed 2 morphologically distinct migrating cell populations with the first type being triggered by a broken physical barrier, which disrupted contact inhibition and the second, late-onset type showing a higher proliferative capacity though appearing less differentiated. This cell subpopulation appeared to be mediated by stimuli other than loss of contact inhibition and ROCK-inhibitor presence. Further exploration of the differences between these cell types may assist in optimizing regenerative treatment options for endothelial diseases.

Machine Learning Analysis of Postkeratoplasty Endothelial Cell Images for the Prediction of Future Graft Rejection.

Purpose: This study developed machine learning (ML) classifiers of postoperative corneal endothelial cell images to identify postkeratoplasty patients at risk for allograft rejection within 1 to 24 months of treatment. Methods: Central corneal endothelium specular microscopic images were obtained from 44 patients after Descemet membrane endothelial keratoplasty (DMEK), half of whom had experienced graft rejection. After deep learning segmentation of images from all patients' last and second-to-last imaging, time points prior to rejection were analyzed (175 and 168, respectively), and 432 quantitative features were extracted assessing cellular spatial arrangements and cell intensity values. Random forest (RF) and logistic regression (LR) models were trained on novel-to-this-application features from single time points, delta-radiomics, and traditional morphometrics (endothelial cell density, coefficient of variation, hexagonality) via 10 iterations of threefold cross-validation. Final assessments were evaluated on a held-out test set. Results: ML classifiers trained on novel-to-this-application features outperformed those trained on traditional morphometrics for predicting future graft rejection. RF and LR models predicted post-DMEK patients' allograft rejection in the held-out test set with >0.80 accuracy. RF models trained on novel features from second-to-last time points and delta-radiomics predicted post-DMEK patients' rejection with >0.70 accuracy. Cell-graph spatial arrangement, intensity, and shape features were most indicative of graft rejection. Conclusions: ML classifiers successfully predicted future graft rejections 1 to 24 months prior to clinically apparent rejection. This technology could aid clinicians to identify patients at risk for graft rejection and guide treatment plans accordingly. Translational Relevance: Our software applies ML techniques to clinical images and enhances patient care by detecting preclinical keratoplasty rejection.

Long-Term Outcomes of Descemet Membrane Endothelial Keratoplasty: Effect of Surgical Indication and Disease Severity.

PURPOSE: The aim of this study was to evaluate clinical outcomes and graft survival in a large patient cohort up to 10 years after Descemet membrane endothelial keratoplasty (DMEK) based on surgical indication and Fuchs endothelial corneal dystrophy (FECD) severity. METHODS: The cohort in this retrospective study included 750 eyes that underwent DMEK for FECD (86%), bullous keratopathy (BK, 9%), and other indications (5%). Based on the modified Krachmer grading, 186 eyes (29%) had moderate FECD (Krachmer grade 3-4) and 440 eyes (68%) had advanced FECD (Krachmer grade 5-6). Main outcome measures were best-corrected visual acuity (BCVA), central corneal thickness, endothelial cell density (ECD), endothelial cell loss (ECL), postoperative complication rate, and graft survival. RESULTS: The mean 10-year BCVA was 0.08 ± 0.28 logMAR (n = 96), and the BCVA remained stable between 5 and 10 years postoperatively (all P > 0.05). The mean ECL at 5 and 10 years was 56% ± 17% (n = 460) and 66% ± 14% (n = 96), respectively ( P < 0.05). The 10-year graft survival rate for the total cohort was 0.85 (95% confidence interval, 0.82-0.89). BCVA and ECD differed at 1 to 5 years between eyes with different surgical indications (all P < 0.05), and FECD eyes had higher graft survival compared with BK eyes (0.90 vs. 0.60, P = 0.001). Moderate FECD eyes had better BCVA, ECD, and graft survival outcomes than advanced FECD eyes (all P < 0.05). Minor graft detachment ( P = 0.04) and lower donor ECD ( P = 0.01) were related to lower 10-year ECD. CONCLUSIONS: Long-term outcomes and graft survival after DMEK were better in FECD eyes than BK eyes and were also related to FECD disease severity. Eyes operated for moderate FECD showed the highest graft survival probability and excellent long-term outcomes.

Impact of Fuchs Endothelial Corneal Dystrophy Severity on Scheimpflug-Derived Parameters After Descemet Membrane Endothelial Keratoplasty.

PURPOSE: The aim of this study was to evaluate how Scheimpflug-derived parameters of eyes with Fuchs endothelial corneal dystrophy (FECD) are influenced by Descemet membrane endothelial keratoplasty (DMEK) depending on FECD severity and the presence of subclinical edema. METHODS: A retrospective cohort study including 115 eyes (115 patients) that underwent DMEK for FECD and a control group of 27 eyes with nonpathological corneas was conducted. Preoperative and 6 months postoperative Scheimpflug imaging was used to analyze pachymetry, presence of tomographic features (loss of isopachs/displacement of the thinnest point/focal posterior depression), and corneal backscatter. FECD severity was based on the modified Krachmer scale and the absence/presence of subclinical edema. RESULTS: Scheimpflug-derived pachymetry, tomographic, and corneal backscatter parameters were correlated with FECD severity, and all changed from preoperatively to postoperatively (all P < 0.05). Postoperative central corneal thickness, anterior and posterior corneal backscatter, and presence of focal posterior depression remained different from the control group (all P < 0.05). Of eyes without preoperative clinical edema (n = 75), 18.7% showed 0 or 1 tomographic feature (no edema group) and 82.4% had 2 or 3 features (subclinical edema group). Compared with the control group, postoperative best-corrected visual acuity for the "no edema" group did not differ (0.03 ± 0.12 vs. -0.02 ± 0.08 logarithm of the minimum angle of resolution, P = 0.150) but was worse for the subclinical edema group (0.06 ± 0.08 vs. -0.02 ± 0.08 logarithm of the minimum angle of resolution, P = 0.001). CONCLUSIONS: For eyes without preoperative edema, more parameters reversed back to 'normal' levels than for eyes with (sub)clinical edema. Although most analyzed parameters correlated with FECD severity, corneal tomography might be best suited for objective grading of disease severity to aid in surgical decision-making.

Long-Term Outcome After Bilateral DMEK for Fuchs Endothelial Corneal Dystrophy.

PURPOSE: The aim of this study was to assess the long-term clinical outcome, complications, and graft survival of bilateral Descemet membrane endothelial keratoplasty (DMEK) in patients with Fuchs endothelial corneal dystrophy. METHODS: This was a retrospective cohort study of 181 patients (362 eyes) with sequential bilateral DMEK for Fuchs endothelial corneal dystrophy. Clinical outcomes were assessed up to 5 years postoperatively. Outcome measures were best-corrected visual acuity, pachymetry, endothelial cell density, graft survival, and complication rates. RESULTS: Contralateral DMEK was performed on average 15 ± 11 months (range: 2-60 months) after the first eye. From 1 until 5 years after DMEK, best-corrected visual acuity, pachymetry, endothelial cell density, and graft survival did not differ between the first and second eyes (all P > 0.05). Graft detachment occurred in 67 eyes (19% [18% first eyes, 19% second eyes], 6% bilateral), graft rejection in 9 eyes (3% [3% first eyes, 2% second eyes], 1% bilateral), glaucoma in 25 eyes (7% [8% first eyes, 6% second eyes], 2% bilateral), and graft failure in 22 eyes (6% [4% first eye, 8% second eye], 2% bilateral). All differences were not significant (all P > 0.05). Five-year graft survival rates were comparable for first and second eyes (0.95 and 0.92, respectively; P = 0.15). CONCLUSIONS: Clinical outcomes after bilateral DMEK are similar in both eyes and sustainable in the longer term. Within the first 5 years, the same complication may rarely occur in the contralateral eye.

P19-A118†Bowman layer onlay: preparation and transplantation (BLOT).

PURPOSE: With the introduction of Bowman layer onlay transplantation (BLOT), the need for BL transplants increases.In this study, the clinical outcomes of BLOT are described and the results of three different BL graft preparation methods are evaluated: manually (m-BL), femtosecond laser-assisted (fs-BL), and femtosecond laser-assisted followed by excimer laser (fs/ex-BL). METHOD: Twenty-one eyes with advanced progressive keratoconus underwent BLOT with m-BL. Best spectacle- and/or best contact lens-corrected visual acuity (BSCVA/BCLVA), corneal tomography, and complications were recorded. Follow-up ranged from 6-36 months with a mean follow-up time of 21±12 months.To evaluate BL preparation methods, Descemet membrane-denuded donor corneas (n=41) were used (n=2 for m-BL, n=18 for fs-BL and n=21 for fs/ex-BL). For fs-BL, corneas were placed on an artificial anterior chamber and different depth cuts were performed with decreasing decrements starting from 30 µm (diameter 9.0 mm). For fs/ex-BL, a superficial flap of 80 µm was created by the femtosecond laser (FEMTO-LDV Z8, Ziemer). Followed by residual stroma ablation by excimer laser (Schwind Amaris 750S) with increasing increments. Grafts were analyzed visually, and graft thickness regularity was evaluated by histological analysis and Transmission Electron Microscopy (TEM). RESULTS: All twenty-one surgeries could be performed without intraoperative complications. Average maximum keratometry changed from 75.8±12D preoperatively to 72.2±9D at the last available follow-up (n=21, P<0.05), and BSCVA/BCLVA improved. Five patients required a regraft; four of those because of a graft detachment within one week.Evaluation of BL-preparation methods: Fs-BL preparation was successful until 14µm cuts (success rate: 12 out of 14, 86%). Fs/ex-BL graft preparation was most successful after an 80µm cut by femtosecond laser with subsequent 60µm ablation by excimer laser (success rate: 15 out of 21, 71%). After the femtosecond laser cut, traces of the femtosecond laser treatment were visible on the flap. While m-BL showed long protruding stromal fibers, they were shorter in fs-BL and absent in fs/ex-BL. CONCLUSION: BL-onlay grafting may be a feasible surgical technique, providing on average -3D of corneal flattening in eyes with advanced progressive keratoconus, while improving patient's visual acuity.Fs-BL and fs/ex-BL preparation may be faster alternatives to manual BL graft preparation.

P07-A139†Guttae in corneal donor tissue.

PURPOSE: To report on the occurrence of guttae in corneal donor tissue. MATERIAL & METHODS: Retrospective database study of discard reasons for corneal donor tissue at Amnitrans EyeBank Rotterdam (AER) for the period from January 2019 to December 2021 and the outcome of an eight-question survey sent to European Eye Bank Association corresponding members addressing the occurrence of corneal guttae and the practice pattern regarding donor tissue with guttae. RESULTS: Between 2019 and 2021 6039 donor corneas were processed at AER. Average discard rate because of guttae in this period was 9 (±4)% (n=552). Most corneas were discarded because of guttae at first evaluation (8%, n=481). Monthly discard rate because of guttae ranged from 3% to 19%. Yearly discard rates related to corneal guttae were 10 (±3)%, 8 (±3)% and 11 (±5)% in 2019, 2020 and 2021, respectively. Average endothelial cell density (ECD) at the first evaluation from 2019-2021 was 2486 (±93) cells/mm2, with average monthly ECD ranging from 2343 to 2642 cells/mm2.Twenty-nine eye banks completed the survey, including 4 located outside Europe. 70% reported a guttae-related discard rate of ≤4. The types of microscope used for the evaluation, the geographical location and the number of guttae permitted do not seem to influence the discard rates. 13 eye banks permitted 0 guttae while 10 banks accepted between 1-10 guttae.The 16 eye banks that responded 'no' to the question whether the contralateral cornea of a guttae-cornea was automatically discarded did report a lower guttae-related discard rate than the other eye banks. CONCLUSION: The high variability of the discard rate due to guttae in donor corneas (ranging from <1% and >12%) is an indication that it is not always easy to detect guttae in donor corneas. Although transplanting corneal grafts with guttae does not necessarily mean that a re-transplantation will be needed on the short term, a vital method to unequivocally determine the presence of guttae in the eye bank seems essential to prevent unnecessary waste of suspect tissue and unnecessary re-surgeries.

Belgian Endothelial Surgical Transplant of the Cornea (BEST cornea) protocol: clinical and patient-reported outcomes of Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) versus Descemet Membrane Endothelial Keratoplasty (DMEK) - a multicentric, randomised, parallel group pragmatic trial in corneal endothelial decompensation.

OBJECTIVES: Corneal blindness is the third most frequent cause of blindness globally. Damage to the corneal endothelium is a leading indication for corneal transplantation, which is typically performed by lamellar endothelial keratoplasty. There are two conventional surgical techniques: Ultra-Thin Descemet Stripping Automated Endothelial Keratoplasty (UT-DSAEK) and Descemet Membrane Endothelial Keratoplasty (DMEK). The purpose of this study is to compare both techniques. METHODS AND ANALYSIS: The trial compares UT-DSAEK and DMEK in terms of clinical and patient reported outcomes using a pragmatic, parallel, multicentric, randomised controlled trial with 1:1 allocation with a sample size of 220 participants across 11 surgical centres. The primary outcome is the change in best-corrected visual acuity at 12 months. Secondary outcomes include corrected and uncorrected vision, refraction, proportion of high vision, quality of life (EQ-5D-5L and VFQ25), endothelial cell counts and corneal thickness at 3, 6 and 12 months follow-up appointments. Adverse events will also be compared 12 months postoperatively. ETHICS AND DISSEMINATION: The protocol was reviewed by ethical committees of 11 participating centres with the sponsor centre issuing the final definitive approval. The results will be disseminated at clinical conferences, by patient partner groups and open access in peer-reviewed journals. GOVERNANCE OF THE TRIAL: Both, trial management group and trial steering committee, are installed with representatives of all stakeholders involved including surgeons, corneal bankers, patients and external experts. TRIAL REGISTRATION NUMBER: NCT05436665.

Corneal endothelial wound healing: understanding the regenerative capacity of the innermost layer of the cornea.

Currently, there are very few well-established treatments to stimulate corneal endothelial cell regeneration in vivo as a cure for corneal endothelial dysfunctions. The most frequently performed intervention for a damaged or dysfunctional corneal endothelium nowadays is corneal endothelial keratoplasty, also known as lamellar corneal transplantation surgery. Newer medical therapies are emerging and are targeting the regeneration of the corneal endothelium, helping the patients regain their vision without the need for donor tissue. Alternatives to donor tissues are needed as the aging population requiring transplants, has further exacerbated the pressure on the corneal eye banking system. Significant ongoing research efforts in the field of corneal regenerative medicine have been made to elucidate the underlying pathways and effector proteins involved in corneal endothelial regeneration. However, the literature offers little guidance and selective attention to the question of how to fully exploit these pathways. The purpose of this paper is to provide an overview of wound healing characteristics from a biochemical level in the lab to the regenerative features seen in the clinic. Studying the pathways involved in corneal wound healing together with their key effector proteins, can help explain the effect on the proliferation and migration capacity of the corneal endothelial cells.

Long-Term Outcomes of Bowman Layer Inlay Transplantation for the Treatment of Progressive Keratoconus.

PURPOSE: To report long-term clinical outcomes and estimated success rates after Bowman layer (BL) inlay transplantation in eyes treated for progressive keratoconus (KC). METHODS: Thirty-five eyes (29 patients) with progressive KC underwent BL inlay transplantation. Best-corrected spectacle and contact lens visual acuity, Scheimpflug-based corneal tomography [simulated and maximum keratometry (Kmax)], central corneal thickness, thinnest point thickness, complications, and success rate were evaluated up to 8 years postoperatively for the total group and 2 subgroups [group 1: preoperative Kmax > 69 diopter (D) (n = 26); group 2: preoperative Kmax < 69D (n = 9)]. RESULTS: Mean logarithm of the minimum angle of resolution best contact lens-corrected visual acuity for the total group and the 2 subgroups did not change from preoperative up to the last available follow-up (all P > 0.05), whereas best spectacle-corrected visual acuity improved for group 1 ( P = 0.03). Group 1 showed an average Kmax reduction of 7D in the first month ( P < 0.001) with no further changes up to 8 years postoperatively ( P > 0.05), whereas no significant changes were observed in group 2 (all P > 0.05). Postoperative KC progression occurred in 4 eyes (n = 3 group 1, n = 1 group 2) and 1 eye (group 2) underwent retransplantation for unsatisfactory visual performance. Kaplan-Meier analysis showed an estimated success rate of 85% at the 5 to 8 years follow-up in group 1 and of 75% at the 5 to 7 years follow-up for group 2. CONCLUSIONS: BL inlay transplantation stabilized KC in most eyes along with preservation of contact lens tolerance up to 8 years postoperatively and may be a successful treatment option, in particular for eyes with progressive advanced KC (Kmax > 69D).

32†Corneal guttae after descemet membrane endothelial keratoplasty (DMEK).

PURPOSE: To report on the occurrence of corneal guttae after Descemet membrane endothelial keratoplasty (DMEK) in eyes operated on for Fuchs endothelial corneal dystrophy (FECD). MATERIAL AND METHODS: Case series of 10 eyes of 10 patients operated on for FECD at a tertiary referral center between 2008 and 2019. Average patient age was 61±12 years and 3 patients were female and 6 were male. Five patients were phakic and 4 pseudophakic. Average donor age was 67±9 years. RESULTS: During routine postoperative consultation, specular microscopy images showed suspected recurrence of guttae in 10 eyes after DMEK. Presence of guttae was subsequently confirmed in 9 cases by confocal microscopy and in one case by histology. Six out of 10 patients (60%) had undergone bilateral DMEK, but all only showed recurrence of guttae in one eye. In 9 eyes guttae recurred after primary DMEK, while in one eye recurrence was after a re-DMEK that has been performed 56 months after the first DMEK with no signs of guttae after primary DMEK. Suspected guttae were visible on specular microscopy images already at 1 month after DMEK in most cases.No guttae had been noted during donor cornea processing in the eye bank. Preoperative donor endothelial cell density (ECD) had been 2643±145 cells/mm2 and 1-year postoperative ECD was 1047±458 cells/mm2 (n=8). CONCLUSION: Recurrence of guttae after DMEK is most likely due to guttae on the donor graft that were not detectable by routine slit-lamp and light-microscopy evaluation in the eye bank. Better screening methods for guttae detection need to be developed for eye banks to avoid releasing tissue for transplantation that contains guttae or is prone for postoperative guttae formation.