Descemet Membrane Endothelial Keratoplasty: Safety and Outcomes: A Report by the American Academy of Ophthalmology

Spokewise iridotomy combined with Descemet stripping automated endothelial keratoplasty in iridocorneal endothelial syndrome

Purpose

Iridocorneal endothelial (ICE) syndrome is a progressive anterior segment disorder that can be tricky to treat. Keratoplasty is commonly used to treat corneal edema in ICE syndrome. However, glaucoma is an important risk factor affecting graft survival. To address this question, we designed a retrospective cohort study to evaluate the effect of Spokewise Iridotomy (SI) on Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) Grafts in Iridocorneal Endothelial (ICE) Syndrome.

Methods

This was a retrospective cohort study. A total of 29 patients were included; 31 eyes with ICE syndrome underwent DSAEK at Peking University Third Hospital between June 2015 and June 2022, including 11 eyes with combined SI during DSAEK. The aim was to explore the effect of SI on vision, glaucoma control, complications, peripheral anterior synechiae recurrence, endothelial cell count, and graft survival.

Results

The median follow-up time was 30.83 months (mo.) in the SI+Endothelial Keratoplasty (EK) group and 6.17 mo in the EK group. The 2-year cumulative survival rate of grafts in the SI+EK group was 100%, compared with the 6-month and 1-year cumulative survival rates of 80.2 and 63.2%, respectively, in the EK group (p = 0.043). The SI+EK group had a lower incidence of immediate postoperative complications (p = 0.005), fewer postoperative anti-glaucoma medications (AGMs) (p = 0.029), smaller peripheral anterior synechiae recurrence (p = 0.001), and significant visual acuity improvement (p < 0.05). More AGMs were used in failed grafts (p = 0.002).

Conclusion

SI can help control intraocular pressure, improve visual acuity, and increase graft survival after DSAEK in ICE syndrome patients.

Clinical Outcomes of Descemet's Membrane Endothelial Keratoplasty without Routine Prophylactic Peripheral Iridotomy

Objectives: To analyze the outcomes and complications of Descemet's membrane endothelial keratoplasty (DMEK) performed without prophylactic peripheral iridotomy (PI). Methods: Design: Retrospective study.

SETTING

Institutional, tertiary care eye hospital.

STUDY POPULATION

All patients who underwent DMEK or DMEK combined with phacoemulsification (DMEK triple) for Fuchs endothelial dystrophy, using a standardized protocol between August 2016 and July 2021, were included. Previous glaucoma surgery, laser PI, aphakia, or complicated pseudophakia were excluded.

MAIN OUTCOME MEASURES

Primary outcomes: Incidence of pupillary block (PB).

SECONDARY OUTCOMES

Graft detachment (GD), rebubbling rates, uncorrected (UCDVA) and best corrected logMAR distance visual acuity (BCDVA), and endothelial cell loss (ECL) at six months. Data were analyzed using the chi-square test and stepwise backward regression analysis. Results: 104 eyes of 72 patients were included. Four eyes (3.8%) developed PB; in two of these cases, standard protocol was not followed. Overall minor GD occurred in 43.2% (n = 45); significant GD was present only in 7 eyes (6.6%). Overall slit lamp rebubbling rate was 30% (n = 35), though only four patients were rebubbled in theatre (3.8%). PB, GD, and rebubbling rates did not vary with the surgeon, surgery, or tamponade (air or SF6 gas). UCDVA, BCDVA, and ECL at 6 months were 0.29 ± 0.31, 0.20 ± 0.28, and 40.46 ± 20.36%, respectively. Conclusions: Compared to previously reported outcomes of DMEK with PI, our results of PI less DMEK using a standardized protocol have a similar incidence of pupillary block, graft detachment, and rebubbling, with comparable visual acuity and endothelial cell loss.

Descemet Membrane Endothelial Patching: Selective Endothelial Replacement in Eyes With Localized Endothelial Dysfunction

ABSTRACT

Descemet membrane (DM) endothelial keratoplasty is considered the gold standard for treating corneal endothelial decompensation and is a true like-for-like replacement. Not all causes of endothelial dysfunction are global, with conditions such as viral endotheliitis affecting discrete populations of endothelial cells. In this study, endothelial grafts matching the area of dysfunction were produced to preserve healthy host cells and limit the immunological burden of new grafts. We have termed this modified DM endothelial keratoplasty procedure DM endothelial patching.

Deep Learning Using Preoperative AS-OCT Predicts Graft Detachment in DMEK

Purpose

To evaluate a novel deep learning algorithm to distinguish between eyes that may or may not have a graft detachment based on pre-Descemet membrane endothelial keratoplasty (DMEK) anterior segment optical coherence tomography (AS-OCT) images.

Methods

Retrospective cohort study. A multiple-instance learning artificial intelligence (MIL-AI) model using a ResNet-101 backbone was designed. AS-OCT images were split into training and testing sets. The MIL-AI model was trained and validated on the training set. Model performance and heatmaps were calculated from the testing set. Classification performance metrics included F1 score (harmonic mean of recall and precision), specificity, sensitivity, and area under curve (AUC). Finally, MIL-AI performance was compared to manual classification by an experienced ophthalmologist.

Results

In total, 9466 images of 74 eyes (128 images per eye) were included in the study. Images from 50 eyes were used to train and validate the MIL-AI system, while the remaining 24 eyes were used as the test set to determine its performance and generate heatmaps for visualization. The performance metrics on the test set (95% confidence interval) were as follows: F1 score, 0.77 (0.57-0.91); precision, 0.67 (0.44-0.88); specificity, 0.45 (0.15-0.75); sensitivity, 0.92 (0.73-1.00); and AUC, 0.63 (0.52-0.86). MIL-AI performance was more sensitive (92% vs. 31%) but less specific (45% vs. 64%) than the ophthalmologist's performance.

Conclusions

The MIL-AI predicts with high sensitivity the eyes that may have post-DMEK graft detachment requiring rebubbling. Larger-scale clinical trials are warranted to validate the model.

Translational Relevance

MIL-AI models represent an opportunity for implementation in routine DMEK suitability screening.

The TCF4 Trinucleotide Repeat Expansion of Fuchs' Endothelial Corneal Dystrophy: Implications for the Anterior Segment of the Eye

Purpose

In the United States, 70% of Fuchs' endothelial corneal dystrophy (FECD) cases are caused by an intronic trinucleotide repeat expansion in the TCF4 gene. CUG repeat RNA transcripts from this expansion accumulate as nuclear foci in the corneal endothelium. In this study, we sought to detect foci in other anterior segment cell types and assess their molecular impact.

Methods

We examined CUG repeat RNA foci appearance, expression of downstream affected genes, gene splicing, and TCF4 RNA expression in corneal endothelium, corneal stromal keratocytes, corneal epithelium, trabecular meshwork cells, and lens epithelium.

Results

CUG repeat RNA foci, the hallmark of FECD in corneal endothelium (found in 84% of endothelial cells), are less detectable in trabecular meshwork cells (41%), much less prevalent in stromal keratocytes (11%) or corneal epithelium (4%), and absent in lens epithelium. With few exceptions including mis-splicing in the trabecular meshwork, differential gene expression and splicing changes associated with the expanded repeat in corneal endothelial cells are not observed in other cell types. Expression of the TCF4 transcripts including full-length isoforms containing the repeat sequence at the 5' end is much higher in the corneal endothelium or trabecular meshwork than in the corneal stroma or corneal epithelium.

Conclusions

Expression of the CUG repeat containing TCF4 transcripts is higher in the corneal endothelium, likely contributing to foci formation and the large molecular and pathologic impact on those cells. Further studies are warranted to examine any glaucoma risk and impact of the observed foci in the trabecular meshwork of these patients.

Long-term Outcomes After Lamellar Endothelial Keratoplasty Compared With Penetrating Keratoplasty for Corneal Endothelial Dysfunction: A Systematic Review

PURPOSE

The purpose of this study is to evaluate long-term outcomes of endothelial keratoplasty (EK) compared with penetrating keratoplasty (PK) for corneal endothelial dysfunction [Fuchs endothelial corneal dystrophy (FECD) and bullous keratopathy (BK)].

METHODS

In this systematic review, we searched PubMed, the Cochrane Library, and Embase up to May 2022 and considered all types of studies addressing our objective. Graft survival at 5, 10, and 15 years was the main outcome.

RESULTS

Fifty cohort studies were included. At 5 years, in FECD and BK, graft survival seemed higher after EK than PK. Two comparative studies showed either a higher 5-year graft survival after EK than PK or no significant differences. Including noncomparative studies, in FECD, the 5-year graft survival ranged from 0.69 to 0.98 for PK, from 0.93 to 1.00 for DSEK, and from 0.93 to 0.99 for Descemet membrane endothelial keratoplasty (DMEK). In BK, the 5-year graft survival ranged from 0.39 to 0.91 for PK, from 0.65 to 0.89 for DSEK, and from 0.84 to 0.95 for DMEK. The 10-year graft survival ranged from 0.20 to 0.90 for PK and from 0.62 to 0.92 for EK. The mean 5-year best spectacle-corrected visual acuity ranged from 0.73 to 0.43 LogMAR for PK, from 0.61 to 0.09 for DSEK, and from 0.31 to 0.05 for DMEK. The 5-year rejection rate ranged from 11.0% to 28.7% for PK, from 5.0% to 7.9% for DSEK, and from 1.7% to 2.6% for DMEK.

CONCLUSIONS

These results suggest a higher 5-year graft survival and better secondary outcomes after EK. Nevertheless, the level of evidence was low.

PROSPERO REGISTRATION

CRD42021260614.

Clinical Outcomes of Toric Intraocular Lenses in Patients with Fuchs Endothelial Corneal Dystrophy

INTRODUCTION

Implantation of toric intraocular lenses (IOLs) in patients with Fuchs endothelial corneal dystrophy (FECD) is still considered relatively contraindicated, without sufficient clinical evidence. Therefore, this study was designed to evaluate the results of toric IOL implantation in patients with FECD.

METHODS

A retrospective case-control study of 28 eyes of FECD patients and 84 eyes of healthy control patients who received toric IOLs during routine cataract surgery was performed. The outcome measures were uncorrected and corrected distance visual acuity, spherical equivalent, and refractive residual astigmatism.

RESULTS

The mean postoperative uncorrected and corrected distance visual acuity in the FECD eyes compared to the control eyes were 0.15 ± 0.14 vs. 0.13 ± 0.17, respectively (P = 0.32), and 0.05 ± 0.08 vs. 0.06 ± 0.10, respectively (P = 0.95). The spherical equivalent in the FECD eyes compared to the control eyes was - 0.29 ± 0.43 vs. - 0.21 ± 0.50, respectively (P = 0.19). The preoperative corneal centroid astigmatism in the FECD eyes compared to the control eyes was 0.85 D@93° ± 2.42° vs. 0.23 D@68° ± 2.50°, respectively (P = 0.43), and the mean preoperative corneal astigmatism magnitude was 2.26 ± 1.1 D vs. 2.28 ± 1.03 D, respectively (P = 0.82). A trend toward higher postoperative refractive centroid astigmatism was found in the FECD eyes compared with the control eyes: 0.24 D@28° ± 0.57° vs. 0.03 D@127° ± 0.53°, respectively (P = 0.09). However, the mean refractive astigmatism magnitude was similar in FECD eyes and the healthy control eyes: 0.52 ± 0.31 D vs. 0.42 ± 0.31 D, respectively (P = 0.44) (D diopters).

CONCLUSION

The postoperative refractive astigmatism (both centroid astigmatism and mean magnitude astigmatism) was no higher than 0.52 D in both groups. Therefore, FECD patients without corneal edema can be considered for toric IOLs.

Descemet’s Membrane Endothelial Keratoplasty for Corneal Endothelial Failure Secondary to Three Types of Phakic Intraocular Lens – Retrospective Study

Purpose

To analyze the outcomes of Descemet's membrane endothelial keratoplasty (DMEK) for corneal endothelial failure secondary to phakic intraocular lens implantation (PIOL) at a reference center for corneal transplantation in Spain.

Design

Retrospective, single-surgeon case series.

Methods

Single-center analysis of patients who underwent DMEK for PIOL-related corneal decompensation between July 2011 and July 2020 with at least 6 months of follow-up postoperatively. Primary outcome was final best-corrected visual acuity (BCVA, logMAR) compared to pre-DMEK BCVA. Secondary outcomes analyzed included post-DMEK refractive spherical equivalent, endothelial cell loss (%ECL), and graft failure.

Results

Sixteen eyes (14 patients) underwent DMEK for PIOL-related corneal decompensation. Mean (SD) time to PIOL explantation was 9.3 (5.0) years, and median (P25-P75) time between PIOL explantation and DMEK surgery was 3 (2-4) months. Median pre-DMEK BCVA was 0.80 (1.08-0.60) logMAR. A statistically significant improvement in BCVA was observed 1 month after DMEK (p = 0.001), and median final BCVA was 0.15 (0.0-0.35) logMAR (p = 0.002). Mean %ECL was 55.6 (18.7) % at 2-year follow-up and 61.7 (11.7) % in eyes with over 4 years of follow-up. Two eyes required re-bubbling (12.5%), one of which ended in primary graft failure (6.2%) and one eye had late endothelial graft failure (LEGF) at 4-year follow-up (1/15 grafts, 6.7%).

Conclusion

In patients with PIOL-related corneal decompensation, DMEK leads to good and clinically significant refractive and visual outcomes in the medium-long term, with a good safety profile. Prospective studies are encouraged to ascertain whether these cases are at increased risk of accelerated endothelial cell loss and LEGF.

Risk factors for intraocular pressure elevation following Descemet membrane endothelial keratoplasty in Asian patients

PURPOSE

To investigate risk factors for increased intraocular pressure (IOP) after Descemet membrane endothelial keratoplasty (DMEK) in Asian patients.

METHODS

Data from January 2015 to February 2021 were obtained from our prospective database. IOP elevation after DMEK was defined as IOP ≥ 22 mmHg or an increase in IOP of ≥ 10 mmHg from baseline. In addition, we examined maximum IOP. Using iCare, we measured IOP 1, 2, 3, and 6 months after DMEK, and every 6 months thereafter. Logistic regression and linear regression were performed to find factors predictive of IOP elevation and maximum IOP, respectively, based on the results of univariate analysis.

RESULTS

We enrolled 90 eyes (mean patient age, 74.9 ± 7.5 years; mean follow-up duration, 25.6 ± 9.9 months) that underwent DMEK. IOP elevation was present in 19 eyes (21%). IOP increased from 12.6 ± 3.9 mmHg preoperatively to a postoperative maximum of 17.0 ± 5.5 mmHg up to 36 months after DMEK (p < 0.0001). In univariate logistic regression analysis for IOP elevation, only one variable, pseudoexfoliation syndrome (PEX) and preexisting glaucoma, was significant (p < 0.05). Preexisting glaucoma without PEX (OR, 19.33; 95% CI, 4.75-93.46), PEX without glaucoma (OR, 7.25; 95% CI, 1.20-41.63), and PEX glaucoma (OR, 58.00; 95% CI, 6.78-1298.29) were associated with higher risk of IOP elevation.

CONCLUSIONS

In this cohort, the eyes of patients with PEX and preexisting glaucoma were found to be prone to IOP elevation after DMEK.

DMEK outcome after one year - Results from a large multicenter study in Germany

PURPOSE

Descemet membrane endothelial keratoplasty (DMEK) accounts for >50% of all corneal transplants in Germany. So far, no data from such a large multicenter study have been published.

METHODS

This retrospective study included 3200 DMEKs at seven departments performed for Fuchs endothelial corneal dystrophy (FECD) or bullous keratopathy (BK). We evaluated best corrected visual acuity (BCVA, logMAR), endothelial cell density (ECD, cells/mm² ), minimal corneal thickness (CT, μm), rebubbling-, primary transplant failure- and immune reaction-rate. Changes over time were evaluated by linear mixed models for repeated measures and correlation with case number by center by weighted linear regression.

RESULTS

For patients without vision-limiting comorbidities (74% of all analysed eyes, n = 2270), mean BCVA improved from 0.6 ± 0.4 logMAR to 0.2 ± 0.2 logMAR 6 months (p < 0.001, n = 1441) and 0.1 ± 0.2 logMAR 12 months (p = 0.001, n = 1402) postoperatively. BK- had a worse BCVA compared to FECD-patients (0.3 ± 0.5 vs. 0.1 ± 0.2 logMAR [p < 0.001] at 1 year). ECD declined from 2465 ± 259 cells/mm² (n = 2876 preoperatively) to 1587 ± 433 cells/mm² after 12 months (p < 0.001, n = 1237). Mean rebubbling rate was 0.4 ± 0.7/eye. 784 eyes (25%) received at least one rebubbling. More rebubblings correlated with a lower ECD, a worse BCVA, a higher CT, and higher transplant failure and rejection rates (p < 0.001, p = 0.013 for BCVA at 12 months). A single rebubbling did not influence the BCVA (p = 0.785). Graft failure rate was 3% (n = 67), rejection rate 1.5% (n = 48).

CONCLUSION

Descemet membrane endothelial keratoplasty increases visual acuity with low transplant failure- and rejection-rates. FECD has a better outcome than BK. Since a quarter of all patients need a rebubbling, this should be included in the informed consent. Remarkably, one rebubbling has no influence on the outcome.

Posterior Segment Air Injection-Assisted Descemet Membrane Endothelial Keratoplasty in Pseudophakic and Vitrectomized Eyes

PURPOSE

This study aimed to present a novel technique for Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic and vitrectomized eyes.

METHODS

The sterile air was injected into the posterior eye segment (anterior vitreous cavity) as a barrier to prevent the fluid of the vitreous cavity flowing into the anterior chamber, levitating the iris-lens diaphragm to flatten the anterior chamber during the surgery. This approach assists in the unfolding of the donor endothelial graft, helping to perform DMEK surgery on patients with a posterior intraocular lens (IOL) and vitrectomy.

RESULTS

Four cases presented with corneal endothelial decompensation (pseudophakic bullous keratopathy) with previous IOL implantation and vitrectomy underwent DMEK with this technique. The Descemet endothelial graft unfolding time after air injection was 68.75 ± 8.96 seconds. No graft displacement occurred during the surgery. The uncorrected and corrected distance visual acuities were improved in 3 of 4 patients. The corneas were transparent, and there was no graft detachment observed postoperatively in all 4 patients.

CONCLUSIONS

The posterior eye segment air injection can reduce the difficulty of unfolding the DMEK graft in patients after IOL implantation and vitrectomy and the potential intraoperative and postoperative complications, allowing for easy performance of DMEK surgery on pseudophakic and vitrectomized eyes for corneal endothelial dysfunction.

Sutured Descemet Membrane Endothelial Keratoplasty in Patients With Complex Anatomy or Difficulty Positioning

PURPOSE

In Descemet membrane endothelial keratoplasty (DMEK), some patients cannot adhere to postoperative positioning requirements or lack anatomic support for a gas bubble in the anterior chamber. We describe a suturing technique that stabilizes the graft postoperatively without tearing or tenting it.

METHODS

One to two 10-0 nylon sutures with a spatulated needle are used to secure DMEK grafts. Tied with minimal tension, the sutures traverse the corneal stroma at a steep, almost perpendicular angle and approach the graft from the limbus at an angle tangential to the circular graft to prevent vaulting the tissue off the central cornea. We report preoperative and postoperative best spectacle-corrected visual acuity, corneal pachymetry, and anterior segment optical coherence tomography confirming graft attachment in 3 patients.

RESULTS

In case 1 (aphakia, postvitrectomy, and positioning difficulty), pachymetry decreased from 637 μm preoperatively to 495 μm and best spectacle-corrected visual acuity improved from 20/70 to 20/50 at postoperative week 1. In case 2 (aphakia, limited follow-up, and medication adherence), pachymetry decreased from 1106 μm preoperatively to 783 μm at postoperative month 1. In case 3 (tube shunt and loss of gas bubble at 2 hours), slit-lamp examination at postoperative day 1 showed corneal clearing and graft attachment. Pachymetry decreased from over 795 μm preoperatively to 582 μm at postoperative month 1. Anterior segment optical coherence tomography confirmed graft attachment in all patients.

CONCLUSIONS

Single or opposing tangentially oriented sutures can be safely applied to secure DMEK grafts postoperatively in challenging cases.

Posterior stromal ripples increase risk of Descemet's membrane endothelial keratoplasty graft detachment worsening over time

PURPOSE

To evaluate anterior segment optical coherence tomography (AS-OCT) features of Descemet's membrane endothelial keratoplasty (DMEK) grafts associated with graft attachment worsening over time.

METHODS

Retrospective case series on patients who received uncomplicated DMEK surgery and for whom subsequent AS-OCT data were available for analysis. Patients' demographics and surgical details were collected. AS-OCT was analysed for graft detachment axial extension, presence of posterior stromal ripples, quadrant involvement (location and number), degree of detachment extension, peripheral roll, presence and amount of air in the anterior chamber (AC). Features associated with re-bubbling and graft detachment worsening over time were identified.

RESULTS

A total of 147 patients with a mean age of 70.8 ± 9.8 years (63% females) were included. AS-OCT was performed at 2.9 ± 2.4 days after surgery. AS-OCT factors associated with re-bubbling were posterior stromal ripples (p = 0.004) and detachment axial extension (p < 0.001). At first follow-up, of the 147 DMEK, 67 showed complete attachment and 80 partial detachment. In those cases of initially completely attached grafts, posterior stromal ripples were associated with the risk of subsequent graft detachment (p = 0.014) together with recipient age (p = 0.043), phaco-combined surgery (p = 0.018) and AS-OCT timing (p = 0.033); while, in the initially partially detached grafts, detachment worsening was associated with posterior stromal ripples (p = 0.025), detachment axial extension (p = 0.003), degrees of detachment involvement (p = 0.029), peripheral roll-in shape (p = 0.033) and presence of air in the AC (p = 0.032). Relative risk (RR) of graft detachment worsening in patients with moderate/severe posterior stromal ripples was 1.75 (95% CI = 1.09-2.81).

CONCLUSION

Posterior stromal ripples and detachment axial extension >1/3 of graft surface area were the main risk factors for detachment worsening over time, and patients showing these features should be monitored closely to identify the need for re-bubbling at an early stage, thus improving surgical outcomes.

Standard vs total keratometry for intraocular lens power calculation in cataract surgery combined with DMEK

PURPOSE

To compare the prediction accuracy of standard keratometry (K) and total keratometry (TK) for intraocular lens (IOL) power calculation in eyes undergoing combined cataract surgery and Descemet membrane endothelial keratoplasty (triple DMEK).

SETTING

Tertiary care academic referral center.

DESIGN

Retrospective case series.

METHODS

Review of 83 eyes (63 patients) that underwent triple DMEK between 2019 and 2021. Biometry measurements were obtained using a swept-source optical biometer (IOLMaster 700). 63 eyes were used for statistical analysis. Mean error, mean absolute error (MAE), SD, median absolute error, maximum absolute error, root mean squared prediction error, and the percentage of eyes within prediction errors of ±0.50 diopters (D) and ±1.00 D were calculated for 9 multivariate and third-generation formulas using K and TK values (Barrett Universal II, Yeo EVO 2.0, Cooke K6, Kane, Pearl-DGS, Haigis, Holladay 1, Hoffer Q, and SRK/T). Formulas were additionally tested by using the prediction for an IOL power 1 D below the IOL used (IOLup1D).

RESULTS

For all formulas, MAE was lower for K than for TK by an average of 0.21 D. The lowest MAE value observed was 0.67 D for "adjusted" SRK/T using K, and the highest MAE values observed were 1.24 D and 1.24 D for nonadjusted Hoffer Q and Haigis using TK, respectively. Overall, lower MAE values were observed for multivariate formulas and SRK/T.

CONCLUSIONS

In triple DMEK eyes, the prediction accuracy of K was higher than that of TK. The most accurate formulas were SRK/T and multivariate formulas using K with the IOLup1D adjustment.

Optimization of patient positioning for improved healing after corneal transplantation

Corneal transplantation is the only solution which avoids loss of vision, when endothelial cells are dramatically lost. The surgery involves injecting gas into the anterior chamber of the eye, to create a bubble that pushes onto the donor cornea (graft), achieving sutureless adherence to the host cornea. During the postoperative period, patient positioning affects the bubble. To improve healing, we study the shape of the gas-bubble interface throughout the postoperative period, by numerically solving the equations of fluid motion. Patient-specific anterior chambers (ACs) of variable anterior chamber depths (ACD) are considered, for either phakic (with natural lens) and pseudophakic (with artificial lens) eyes. For each AC, gas-graft coverage is computed for different gas fill and patient positioning. The results show that the influence of positioning is negligible, regardless of gas filling, as long as the ACD is small. However, when the ACD value increases, patient positioning becomes important, especially for pseudophakic ACs. The difference between best and worst patient positioning over time, for each AC, is negligible for small ACD but significant for larger ACD, especially for pseudophakic eyes, where guidelines for optimal positioning become essential. Finally, mapping of the bubble position highlights the importance of patient positioning for an even gas-graft coverage.

Risk Factors for Descemet Membrane Endothelial Keratoplasty Rejection: Current Perspectives- Systematic Review

Descemet membrane endothelial keratoplasty (DMEK) is a corneal endothelial transplantation procedure with selective removal of a patient's defective Descemet membrane and endothelium. It is replaced with a healthy donor Descemet membrane and endothelium without a stromal component. Corneal graft rejection can be at the level of epithelium, stroma as well endothelium. DMEK graft rejection is relatively less common than rejection with DSAEK or penetrating keratoplasty, and a good outcome may be achieved with prompt management. The clinical picture of DMEK rejection is usually similar to endothelial rejection in Descemet Stripping Endothelial Keratoplasty (DSEK/DSAEK), which generally manifests as pain, redness, reduction in visual acuity, stromal edema, endothelial rejection line, keratic precipitates at the back of the cornea and corneal neovascularization. However, more subtle forms of rejection or immune reactions are more common in DMEK compared to DSAEK eyes. Early clinical diagnosis, prompt intervention, and meticulous management safeguard visual acuity and graft survival in these cases. Intensive topical steroids form the mainstay in the management of DMEK rejection. Sometimes, oral or intravenous steroids or other systemic immunomodulators may be required. DMEK graft failure can be primary or secondary, and failure usually requires a second procedure in the form of repeat DMEK or DSEK or penetrating keratoplasty (PKP). A detailed literature search was performed using search engines such as Google Scholar, PubMed, and Google books, and a comprehensive review on DMEK rejection was found to be lacking. This review is a comprehensive update on the risk factors, pathophysiology, primary and secondary graft failure, recent advances in diagnosis, prevention of rejection, and updates in the management of DMEK rejection. The review also discusses the differential diagnosis of DMEK failure and rejection, prognosis, and future perspectives considering DMEK failure and rejection.

Five-Year Safety and Efficacy of Femtosecond Laser-Assisted Descemet Membrane Endothelial Keratoplasty

PURPOSE

The purpose of this study was to evaluate 5-year safety and efficacy outcomes of femtosecond-enabled Descemet membrane endothelial keratoplasty (F-DMEK) in patients with Fuchs' endothelial dystrophy (FED).

METHODS

This was a retrospective study, including patients with FED and cataract who underwent either F-DMEK (16 eyes of 15 patients) or manual DMEK (M-DMEK) (42 eyes of 37 patients) combined with cataract extraction. Outcome measures included visual acuity, graft detachment, graft survival, and endothelial cell loss.

RESULTS

The average follow-up in F-DMEK and M-DMEK was 57.1 ± 12.4 months and 58.5 ± 17.3 months, respectively ( P = 0.757). The rates of primary failure (0% vs. 9.5%, P = 0.567), secondary failure (0% for both), and graft rejection (0% vs. 7.1%, P = 0.533) did not differ significantly between the groups. Improvement in best spectacle-corrected visual acuity was similar in F-DMEK and M-DMEK (0.32 ± 0.27 logarithm of the minimum angle of resolution and 0.35 ± 0.44 logarithm of the minimum angle of resolution, respectively, P = 0.165) and persisted at 2, 3, 4, and 5 years and at the last follow-up. The rates of graft detachment and rebubbling were significantly lower with 6.25% in F-DMEK and 33.3% in M-DMEK ( P = 0.035). Cell-loss rates were lower in F-DMEK compared with M-DMEK throughout the follow-up, significantly so up to 2 years with a difference of 8.6% at 1 year ( P = 0.023), 11.8% at 2 years ( P = 0.021), 7.6% at 3 years ( P = 0.088), 5.8% at 4 years ( P = 0.256), 13.6% at 5 years ( P = 0.169), and 7.1% at the final follow-up ( P = 0.341).

CONCLUSIONS

F-DMEK had an excellent safety and efficacy profile which was maintained over 5 years of follow-up. Lower endothelial cell-loss rates in F-DMEK compared with M-DMEK may help extend the duration of graft survival.

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.

Assessing the Learning Curve for DMEK Using Post-Procedural Clinical Outcomes-Comparison of Four Different Surgeons during Two Different Periods

PURPOSE

Evaluating the learning curve of individual surgeons for Descemet Membrane Endothelial Keratoplasty (DMEK) and Triple-DMEK and assessing outcome with experience.

METHODS

The first 41 and the last 41 surgeries of each of the four surgeons were retrospectively included. Surgery duration and graft preparation time were recorded. Corrected distance visual acuity (CDVA, logMAR) and central corneal thickness (CCT, µm) were collected preoperatively after 6 and 12 months, as well as postoperative complications, e.g., re-bubbling or repeat penetrating keratoplasty.

RESULTS

Surgical duration for Triple-DMEK and DMEK decreased significantly by 21 min and 14 min between the two periods (p < 0.001; p < 0.001). Graft preparation time decreased significantly from 13.3 ± 5.2 min (95%CI 12.8-14.3) in period 1 to 10.7 ± 4.8 min (95%CI 10.2-11.4) in period 2 (p = 0.002). The postoperative changes in CDVA and CCT over both periods were not significant (p = 0.900; p = 0.263). The re-bubbling rate decreased significantly from 51.2% in period 1 to 26.2% in period 2 (p < 0.001). The repeat penetrating keratoplasty (PKP) was 7.3% in period 1 and 3.7% in period 2 (p = 0.146). Re-DMEK was necessary in 6.1% in period 1 and 4.9% in period 2 (p = 0.535). Several parameters showed significant differences between the surgeons in both periods (surgical duration: period 1: p < 0.001, period 2 p < 0.001; graft preparation: period 1: p < 0.001, period 2 p < 0.001).

CONCLUSION

Significant decrease in surgery duration, graft preparation time, and the re-bubbling rate can be attributed to gained individual experience.

Clinical outcomes of presbyopia-correcting intraocular lenses in patients with Fuchs endothelial corneal dystrophy

Fuchs endothelial corneal dystrophy (FECD) is considered a contraindication for the implantation of presbyopia-correcting IOLs, without sufficient corroborating evidence. A Retrospective, case-control study. Nineteen eyes of ten patients with grade 2-5 FECD (study group) and 57 healthy eyes of 57 patients (control group) who underwent cataract surgery with implantation of presbyopia-correcting IOLs, at the Ein-Tal Eye Center, Tel Aviv, Israel, were included. The target refraction was emmetropia for both groups. Two subgroups of IOLs were analyzed separately: extended depth of focus (EDOF), (9 eyes of FECD patients and 27 eyes of control patients) and multifocal IOLs (10 eyes of FECD patients and 30 eyes of control patients). Main outcome measures were visual acuity and refraction 6 weeks after the surgery. Secondary outcomes were patient perceptions of visual acuity, spectacle independence, photic phenomena and satisfaction scores, reported in a self-assessment questionnaire. FECD patients in the EDOF IOL subgroup had inferior uncorrected distance visual acuity (P = 0.007) and better uncorrected near visual acuity (P = 0.001) compared to the controls. They had less spectacle independence for the intermediate range (P = 0.01) and overall (P = 0.006). However, they did not have more photic phenomena. In the multifocal IOL subgroup, no significant differences were found between the FECD and the control group in visual acuity for all ranges and in spectacle independence. FECD patients had more photic phenomena than the controls (P = 0.006), but it did not interfere with daily life activities. There was no difference in post-operative mean spherical equivalent, patient reported visual perception, and general satisfaction between FECD and control patients in both groups. Our results suggest that presbyopia-correcting IOLs can be carefully considered in patients with grade 2-5 FECD, with slightly inferior results compared with healthy eyes.

The effect of anterior segment parameters on surgical success of Descemet membrane endothelial keratoplasty: a prospective study

PURPOSE

To investigate how anterior segment parameters affect the success of Descemet membrane endothelial keratoplasty (DMEK) in patients with endothelial insufficiency without stromal opacities and to identify factors predisposing them to repeat keratoplasty.

METHODS

Our prospective observational study included patients who underwent primary DMEK for Fuchs' endothelial dystrophy and pseudophakic bullous keratopathy between March 2019 and March 2020. After a detailed ophthalmologic examination, corneal topographic analysis, anterior segment optical coherence tomography (AS-OCT) scans, endothelial cell density (ECD) and axial length (AL) measurements were performed. Surgical success was defined as no endothelial dysfunction during follow-up. Changes in the parameters and how preoperative parameters affect surgical success were investigated.

RESULTS

In 43 eyes of 43 patients (mean age: 68.58 ± 8.51 years), mean visual acuity was 1.73 ± 0.74 LogMAR before DMEK and 0.31 ± 0.29 LogMAR in the final visit. Central corneal thickness (CCT, p = 0.026) and mean anterior chamber depth (ACD, p = 0.001) affected surgical success. Preoperative CCT values greater than 770 µm increased the risk of repeat keratoplasty by 8.75-fold, whereas preoperative ACD values less than 2.5 mm increased the risk by 2.92-fold.

CONCLUSION

Preoperative higher CCT and lower ACD values were associated with surgical failure after DMEK. Early surgery may be considered for more successful results.

TRIAL REGISTRATION

This prospective study has been registered on the ClinicalTrials.gov system with the registration number NCT04420429 on 06/06/2020.

Rebubbling and graft failure in Descemet membrane endothelial keratoplasty: a prospective Dutch registry study

AIMS

To identify risk factors for rebubbling, and early graft failure after Descemet membrane endothelial keratoplasty (DMEK).

METHODS

In this prospective registry study, all consecutive DMEK procedures registered in the Netherlands Organ Transplant Registry were assessed (n=752). Univariable and multivariable analysis was performed using logistic regression. The effect of rebubbling on endothelial cell density was analysed using a linear mixed model.

RESULTS

144 of 752 (19%) eyes underwent rebubbling. Rebubbling was successful in 101 eyes (70%). In eyes that underwent rebubbling, the graft failure rate was significantly higher than eyes that did not undergo rebubbling (30% vs 9%, respectively; OR: 4.28, 95% CI 2.72 to 6.73, p<0.001). In multivariable analysis, independent risk factors for rebubbling were surgical complication (OR: 2.28, 95% CI 1.20 to 4.33, p=0.012) and older recipient age (OR: 1.04 (per increase of 1 year), 95% CI 1.01 to 1.07, p=0.003). Risk factors for developing graft failure within 3 months were transplant before 2016 (OR: 3.32, 95% CI 1.87 to 5.90, p<0.001), and surgical complication (OR: 2.93, 95% CI 1.42 to 6.04, p=0.004). Throughout the study period, rebubbling and early graft failure were inversely related. Eyes that underwent rebubbling showed significantly lower endothelial cell densities at 3, 6 and 12 months compared with eyes that did not undergo rebubbling (all p<0.001).

CONCLUSIONS

This Dutch registry study identified independent risk factors for DMEK graft detachment leading to rebubbling, namely recipient age and surgical complication, and early graft failure, namely transplantation before 2016 and surgical complication. Rebubbling was associated with significantly higher endothelial cell loss in the first year after surgery.

Deep Learning Model for the Detection of Corneal Edema Before Descemet Membrane Endothelial Keratoplasty on Optical Coherence Tomography Images

Purpose

Descemet membrane endothelial keratoplasty (DMEK) is the preferred method for treating corneal endothelial dysfunction, such as Fuchs endothelial corneal dystrophy (FECD). The surgical indication is based on the patients' symptoms and the presence of corneal edema. We developed an automated tool based on deep learning to detect edema in corneal optical coherence tomography images. This study aimed to evaluate this approach in edema detection before Descemet membrane endothelial keratoplasty surgery, for patients with or without FECD.

Methods

We used our previously described model allowing to classify each pixel in the corneal optical coherence tomography images as "normal" or "edema." We included 1992 images of normal and preoperative edematous corneas. We calculated the edema fraction (EF), defined as the ratio between the number of pixels labeled as "edema," and those representing the cornea for each patient. Differential central corneal thickness (DCCT), defined as the difference in central corneal thickness before and 6 months after surgery, was used to quantify preoperative edema. AUC of EF for the edema detection was calculated for Several DCCT thresholds and a value of 20 µm was selected to define significant edema as it provided the highest area under the curve value.

Results

The area under the curve of the receiver operating characteristic curve for EF for the detection of 20 µm of DCCT was 0.97 for all patients, 0.96 for Fuchs and normal only and 0.99 for non-FECD and normal patients. The optimal EF threshold was 0.143 for all patients and patients with FECD.

Conclusions

Our model is capable of objectively detecting minimal corneal edema before Descemet membrane endothelial keratoplasty surgery.

Translational Relevance

Deep learning can help to interpret optical coherence tomography scans and aid the surgeon in decision-making.

Surgical goniolens for tag identification and removal in DMEK surgery

INTRODUCTION

We describe a novel technique for identifying endothelial Descemet membrane (DM) tags remaining after descemetorhexis in patients undergoing Descemet membrane endothelial keratoplasty (DMEK) surgery.

METHODS

A surgical goniolens is applied to the corneal surface after descemetorhexis in order to visualize the peripheral inner corneal layer at 360° and identify endothelial-DM tags.

RESULTS

A detailed visualization of the peripheral inner corneal layer is possible using goniolens, without using any staining in the anterior chamber.

CONCLUSION

The technique may be used to screen the posterior corneal surface for any retained endothelial-DM tags. It may to lower the risk of remaining tags and indirectly lower the incidence of DMEK graft detachment.

The need of rebubbling in case of small graft detachments after Descemet Membrane Endothelial Keratoplasty (DMEK)

Purpose

To investigate the need of rebubbling for small graft detachments after Descemet Membrane Endothelial Keratoplasty (DMEK).

Methods

In this retrospective study we evaluated 111 eyes from 111 patients that showed graft detachment after DMEK surgery and have achieved graft adherence by injection of air or 20% sulfur hexafluoride (SF6) to the anterior chamber (rebubbling group; n = 57) or by spontaneous adherence without intervention (control group; n = 54) at final examination. Subgroups in terms of the maximum height and in terms of the detachment area in relation to graft area were formed. Outcome measures were the increase in best-corrected visual acuity (BCVA) and the decrease in central corneal thickness (CCT) from the measurement before DMEK to six months after surgery and postoperative endothelial cell density.

Results

BCVA increased in the rebubbling group and the control group, the difference being 0.22 logMAR, p = 0.048. For eyes with a maximum height less than 500  µm, the increase of BCVA was 0.39 ± 0,36 logMAR in the control group and 0.62 ± 0,53 logMAR in the rebubbling group, p = 0.045. There was no difference of statistical significance of BCVA between both groups regarding the detachment area of less than 20% in relation to graft area. The mean decrease in CCT and postoperative endothelial cell density showed no significant difference between the rebubbling group and the control group.

Conclusion

Compared to spontaneous graft adherence, a rebubbling shows no beneficial effect on the clinical outcome for small detached DMEK grafts. Rebubbling does not decrease postoperative endothelial cell density.

Graft Detachment after Descemet Membrane Endothelial Keratoplasty with and without Cataract Surgery

PURPOSE

To evaluate graft detachment after Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes and DMEK combined with cataract surgery (triple DMEK).

DESIGN

Analysis of 3 single-center prospective cohort studies and 1 randomized controlled trial.

PARTICIPANTS

Participants with Fuchs' endothelial corneal dystrophy.

METHODS

A validated neural network for image segmentation quantified graft detachment on anterior segment OCT (AS-OCT) images 3 days after DMEK and at the 2-week postoperative visit. Area and volume of graft detachment were compared between DMEK only and triple DMEK using generalized estimating equation models and adjusting for participant age and the size of the air bubble.

MAIN OUTCOME MEASURES

Area and volume of DMEK graft detachment.

RESULTS

Among 207 participants with 270 eyes included, 75 pseudophakic eyes had DMEK only and 195 eyes had triple DMEK. A total of 147 eyes had less than one third of detachment at day 3. In 139 of these eyes (95%), detachment was still less than one third at the 2-week scan, indicating that postoperative graft detachment at 2 weeks occurred mainly in eyes with early detachment. When superimposing all 3-dimensional maps from 2 weeks after surgery, the central graft was mainly attached and detachment was located at the graft margin. The mean area of graft detachment decreased from 28% in DMEK only and 38% in triple DMEK to 16% in DMEK only and 25% in triple DMEK at the 2-week postoperative visit. At 2 weeks, the mean area of detachment was 1.85-fold higher (95% confidence interval [CI], 1.34-2.56) and the mean volume was 2.41-fold higher (95% CI, 1.51-3.86) in triple DMEK compared with DMEK. A total of 46 eyes received rebubbling procedures, with 7 eyes (9%) in the DMEK group and 39 eyes (20%) in the triple DMEK group (adjusted risk ratio, 3.1; 95% CI, 1.3-7.1), indicating that rebubbling was more common in eyes undergoing triple DMEK.

CONCLUSIONS

Automated segmentation of AS-OCT images allowed precise quantification of graft detachment over time and identified DMEK combined with cataract surgery as a risk factor. Frequency of operative follow-up might be guided by extent of detachment in the first postoperative days after DMEK.

A review of techniques and outcomes of endothelial keratoplasty in congenital hereditary endothelial dystrophy

Congenital hereditary endothelial dystrophy affects the Descemet membrane and endothelium, resulting in corneal decompensation. Penetrating keratoplasty (PKP) has been the gold-standard surgical management until recently; however, at present, endothelial keratoplasty (DSEK/DSAEK/n-DSEK: Descemet-stripping or non-Descemet stripping endothelial keratoplasty and DMEK/n-DMEK: Descemet membrane endothelial keratoplasty) is being preferred due to lesser intraoperative and postoperative complications, early visual recovery, and comparable visual outcomes. Endothelial keratoplasty (EK) can be challenging, especially in pediatric eyes with CHED due to smaller eyeballs, shallow anterior chambers, phakic status, and poor intraoperative visibility due to thick and hazy corneas. A total of 198 articles matched our search strategy. After screening for duplication and going through the titles and abstracts, 12 relevant original articles, one case series, and six case reports were included in this review. Various surgical modifications have to be adopted in comparison to adult eyes to overcome the aforementioned difficulties. Regardless, studies have shown favorable visual outcomes with better graft survival and fewer complications in eyes that underwent EK compared to PKP. Hence, timely surgical intervention and strict amblyopia management can result in better final visual outcomes. The purpose of this review is to summarize various intraoperative difficulties and the surgical modifications required, different surgical techniques, visual and graft-related outcomes, and various complications of EK in CHED eyes.

The usefulness of lutein/trypan blue vital dye for the staining of corneal endothelium: a pilot study on DMEK pretreated tissues

PURPOSE

The study aims to evaluate the usefulness of lutein/trypan blue vital dye for the staining of corneal tissues and endothelium-Descemet membrane (EDM) for Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Sixteen human corneal tissues (Eye Bank, Rome, Italy) were used. Corneal endothelium was tested at 25 s (T0), 1 min (T1), 2 min (T2), and 4 min (T4) from dye addition. Staining intensity and cell counting were compared. Stripped EDM was analyzed for selected apoptotic (AP, caspases, BCL2, BAX) and differentiation (VEGF-A, TGF-β1RI, SMAD3/7, SMA) targets and changes in target expression. Protein extracts were analyzed through SDS-PAGE/IB.

RESULTS

Although trypan blue staining produced the same color intensity of lutein/trypan blue dye in half the time, lutein/trypan blue reached a good and adequate color intensity at T4, which persisted even on excised and washed EDM grafts. Lutein/trypan blue-stained EDM showed a reduced number of blue-stained cells and AP immunoreactivity was significantly reduced in the same samples. An increased BCL2 transcript and a reduced BAX transcript were detected in lutein/trypan blue-stained EDM. No significant changes were observed for the main effector caspases (3/9) upon both treatments and the target genes representative of endothelial cell trans-differentiation (TGF-β1RI, SMAD3/7, SMA). A trend in vascular endothelial growth factor (VEGF-A) regulation was observed in lutein/trypan blue-treated EDM grafts.

CONCLUSION

Obtained results suggest that lutein/trypan blue dye deserves attention in the DMEK field and support the potential routine use of this dye as a valid alternative to trypan blue for all procedures devoted to the assessment of endothelial cell viability and visualization of EDM graft before DMEK grafting.

Outcomes of Descemet Membrane Endothelial Keratoplasty Using Cornea From Elderly Donors Aged 80 Years and Older: In the Aftermath of Current Donor Shortage

PURPOSE

The purpose of this study was to report the outcomes of Descemet membrane endothelial keratoplasty (DMEK) using corneas from elderly donors aged 80 years and older.

METHODS

Eighty eyes of 78 patients who underwent DMEK-only or DMEK combined with cataract extraction (triple-DMEK) with surgeon-prepared graft between April 2016 and March 2020 were reviewed. Corrected distance visual acuity, endothelial cell density (ECD), and endothelial cell loss after 6 months, 1 year, and 2 years were analyzed.

RESULTS

The mean donor age was 83.6 ± 3.7 years (range: 80-100 years), and the mean donor ECD was 2889 ± 177 cells/mm 2 (range: 2604-3460 cells/mm 2 ). The mean recipient age was 67.2 ± 6.9 years (range: 60-89 years), and the mean follow-up was 21 ± 11 months (range: 6-52 months). The mean corrected distance visual acuity improved from a preoperative value of 1.36 ± 0.67 logarithm of the minimum angle of resolution to 0.22 ± 0.18 at 6 months (n = 75), 0.21 ± 0.2 at 1 year (n = 64), and 0.23 ± 0.3 logarithm of the minimum angle of resolution at 2 years (n = 41), respectively ( P < 0.001). In 72 eyes (96%), the graft remained transparent until the last follow-up visit. The mean postoperative ECD was 2073 ±336 (n = 75), 1951 ± 379 (n = 65), and 1807 ± 431 cells/mm 2 (n = 41) at 6 months, 1 year, and 2 years, respectively. Five eyes (6.7%) had donor detachments of which 4 required rebubbling. Two grafts failed after 1 year, and 2 eyes (2.6%) had graft rejection, of which 1 eye was reverted successfully by medical management.

CONCLUSIONS

Cornea from elderly donors aged 80 years and older with good selection criteria may be considered for DMEK with successful outcomes. For India and other countries with unmet tissue needs, every best single cornea counts.

Quiescent innate and adaptive immune responses maintain the long-term integrity of corneal endothelium reconstituted through allogeneic cell injection therapy

This study aims to clarify the immunogenicity in acquired and innate immune responses of cultured human corneal endothelial cells (hCECs) applied for cell injection therapy, a newly established modality for corneal endothelium failures. Thirty-four patients with corneal endothelial failure received injection of allogeneic hCEC suspension into anterior chamber. No sign of immunological rejection was observed in all 34 patients during the 5-8 years postoperative follow-up period. Cell injection therapy was successful in 2 patients treated for endothelial failure after penetrating keratoplasty and one patient with Descemet membrane stripping automated endothelial keratoplasty failure. ELISPOT assays performed in allo-mixed lymphocyte reaction to the alloantigen identical to that on the injected hCECs, elicited sparse IFN-γ-specific spots in the peripheral blood mononuclear cells of patients who received hCEC injection. The therapy generated simple and smooth graft-host junctions without wound stress. The injection of C57BL/6 CECs into the anterior chamber of BALB/c mice, which rejected C57BL/6 corneas 6 weeks ago, induced no sign of inflammatory reactions after the second challenge of alloantigen. Collectively, injection of the hCEC cell suspension in the aqueous humor induces immune tolerance that contributes to the survival of the reconstituted endothelium.

A machine learning approach to explore predictors of graft detachment following posterior lamellar keratoplasty: a nationwide registry study

Machine learning can be used to explore the complex multifactorial patterns underlying postsurgical graft detachment after endothelial corneal transplantation surgery and to evaluate the marginal effect of various practice pattern modulations. We included all posterior lamellar keratoplasty procedures recorded in the Dutch Cornea Transplant Registry from 2015 through 2018 and collected the center-specific practice patterns using a questionnaire. All available data regarding the donor, recipient, surgery, and practice pattern, were coded into 91 factors that might be associated with the occurrence of a graft detachment. In this research, we used three machine learning methods; a regularized logistic regression (lasso), classification tree analysis (CTA), and random forest classification (RFC), to select the most predictive subset of variables for graft detachment. A total of 3647 transplants were included in our analysis and the overall prevalence of graft detachment was 9.9%. In an independent test set the area under the curve for the lasso, CTA, and RFC was 0.70, 0.65, and 0.72, respectively. Identified risk factors included: a Descemet membrane endothelial keratoplasty procedure, prior graft failure, and the use of sulfur hexafluoride gas. Factors with a reduced risk included: performing combined procedures, using pre-cut donor tissue, and a pre-operative laser iridotomy. These results can help surgeons to review their practice patterns and generate hypotheses for empirical research regarding the origins of graft detachments.

Descemet membrane endothelial keratoplasty: Update on preoperative considerations, surgical techniques, and outcomes

Descemet membrane endothelial keratoplasty (DMEK) is the closest to the physiological replacement of endothelial cells. In the initial years, the technique was surgically challenging. Over the years, with better understanding and modifications in the surgical steps, the technique has evolved as an alternative to more popular procedure Descemet stripping endothelial keratoplasty. The article highlights the various preoperative, intraoperative, and postoperative nuances of DMEK. Additionally, it summarizes the various comparative and noncomparative studies on DMEK outcomes.

Hotspots and trends in ophthalmology in recent 5 years: Bibliometric analysis in 2017–2021

Purpose

The purpose of this study was to investigate the hotspots and research trends of ophthalmology research.

Method

Ophthalmology research literature published between 2017 and 2021 was obtained in the Web of Science Core Collection database. The bibliometric analysis and network visualization were performed with the VOSviewer and CiteSpace. Publication-related information, including publication volume, citation counts, countries, journals, keywords, subject categories, and publication time, was analyzed.

Results

A total of 10,469 included ophthalmology publications had been cited a total of 7,995 times during the past 5 years. The top countries and journals for the number of publications were the United States and the Ophthalmology. The top 25 global high-impact documents had been identified using the citation ranking. Keyword co-occurrence analysis showed that the hotspots in ophthalmology research were epidemiological characteristics and treatment modalities of ocular diseases, artificial intelligence and fundus imaging technology, COVID-19-related telemedicine, and screening and prevention of ocular diseases. Keyword burst analysis revealed that “neural network,” “pharmacokinetics,” “geographic atrophy,” “implementation,” “variability,” “adverse events,” “automated detection,” and “retinal images” were the research trends of research in the field of ophthalmology through 2021. The analysis of the subject categories demonstrated the close cooperation relationships that existed between different subject categories, and collaborations with non-ophthalmology-related subject categories were increasing over time in the field of ophthalmology research.

Conclusions

The hotspots in ophthalmology research were epidemiology, prevention, screening, and treatment of ocular diseases, as well as artificial intelligence and fundus imaging technology and telemedicine. Research trends in ophthalmology research were artificial intelligence, drug development, and fundus diseases. Knowledge from non-ophthalmology fields is likely to be more involved in ophthalmology research.

Effect of Collagenase A on Descemet Membrane Endothelial Keratoplasty Scroll Tightness

PURPOSE

The scrolling properties of the Descemet membrane endothelial keratoplasty (DMEK) graft are essential for surgical success. Currently, there is limited knowledge on what dictates the tightness of the DMEK scroll. The purpose of this study was to determine the impact of temperature and protein digestion on DMEK graft scroll tightness.

METHODS

For the temperature experiment, a total of 28 eyes were used for this study. Scrolls in the cold group were kept at 4°C while scrolls in the hot group were kept at 37°C. Scroll width was recorded at the 5-, 15-, and 30-minute mark. For the protein digestion experiment, a total of 18 eyes were exposed to collagenase A (10 CDU/mL) in Optisol solution. Scroll width was recorded at the time points of 1, 3, 5, 10, and 20 minutes.

RESULTS

The results of the temperature experiment did not yield any statistically significant changes in the mean scroll width of the DMEK scrolls across both temperature ranges and observation times. For the protein digestion experiment, the mean scroll width grew from 1.85 mm to 2.13 mm from the beginning of the experiment until the final observation at 20 minutes. This is a 14.7% change over 20 minutes with a P value (<0.001), exemplifying a statistically significant change in scroll width.

CONCLUSIONS

Temperature did not have any significant effect over scroll tightness, but scroll tightness decreased with collagenase exposure.

Graft Size and Double Scroll Formation Rate in Descemet Membrane Endothelial Keratoplasty

PURPOSE

This study aimed to evaluate the usefulness of intentional double scroll formation of donor Descemet membrane (DM) inside a glass tube inserter (the Fogla technique) in DM endothelial keratoplasty (DMEK) for controlled insertion and unfolding of grafts.

METHODS

Eleven consecutive patients who underwent DMEK were included in this study. We sought to specify graft characteristics in which double scroll configuration was successfully formed using the Fogla technique. We compared donor age, graft size, surgical time, unfolding time, and visual outcomes between patients with and without double scroll configuration. The ability to form double scroll formation of DM grafts of various diameters and unfolding time of DM grafts was evaluated using total seven eye-bank eyes in ex vivo experiments.

RESULTS

A double scroll configuration inside a glass tube was successfully obtained in six DMEK grafts (54.5%). When comparing clinical features between those with and without double scroll configuration, only graft size was significantly larger in those with double scroll configuration (7.9 ± 0.2 mm) than in those without (7.4 ± 0.4, P = 0.03). There were no significant differences in other features and clinical outcomes, although unfolding-time was shorter in eyes with double scroll configuration (4.6 ± 2.0 min) compared to those without (8.6 ± 8.1, P = 0.21). Ex vivo experiments showed that unfolding time was significantly shorter in double scroll configuration (2.71 ± 0.49 min) than in single scroll (5.02 ± 0.79, P = 0.01).

CONCLUSIONS

A double scroll configuration within a glass tube can be obtained more frequently in larger DMEK grafts (8.0 mm in diameter), which may result in easier and faster DMEK procedures.

Impact of vaccination on keratoplasty

PURPOSE OF REVIEW

Corneal graft rejection has been reported after coronavirus disease 2019 (COVID-19) vaccination. The purpose of this review is to evaluate the literature regarding corneal graft rejection after vaccination, including rejection rates and risk factors. We aim to create a framework to identify patients who are at higher risk for graft rejection and may warrant consideration of prophylactic interventions.

RECENT FINDINGS

Graft rejection has been reported following administration of mRNA, viral vector, and inactivated whole-virion COVID-19 vaccines. Most cases had additional risk factors associated with rejection. Vaccination increases circulation of proinflammatory cytokines, CD4+ and CD8+ T-cell responses, and antispike neutralizing antibody, all of which may contribute to graft rejection. Two prospective studies have found no relationship between recent vaccination and rejection but 20% of cornea specialists report to have seen a vaccine-associated rejection and 22% recommend delaying vaccination in certain circumstances. Many specialists recommend prophylactic topical corticosteroids before and after vaccination to mitigate rejection risk but there is no evidence to support this practice on a wider scale.

SUMMARY

Our framework identified 96.8% of penetrating keratoplasty patients with vaccine-associated rejection as higher risk. Further research is needed in order to develop evidence-based guidelines.

Trends in Early Graft Failure Leading to Regrafting After Endothelial Keratoplasty in the United States

PURPOSE

The purpose of this study was to report trends in the prevalence of early graft failure after endothelial keratoplasty in the United States.

METHODS

Descemet membrane endothelial keratoplasty (DMEK) and Descemet stripping automated endothelial keratoplasty (DSAEK) graft volumes were collected from records maintained by 6 major eye banks in the United States from January 1, 2013, to December 31, 2018. The prevalence and presumed cause of early graft failures (defined as a graft with persistent edema or regrafted within 8 weeks after keratoplasty) each year were sourced from surgeon-reported adverse events. Failed graft cases from the 3 eye banks were compared with nonfailures at the donor and recipient levels to perform subset analysis of factors associated with early graft failure.

RESULTS

A total of 51,887 endothelial keratoplasty tissues were distributed during the study period; 72% were DSAEK grafts. The total number of early graft failures reported was 168 of 14,284 (1.18%) for DMEK and 322 of 37,603 (0.86%) for DSAEK. Early DMEK failures decreased from 2013 (7.69%) to 2018 (0.68%). In generalized linear mixed model analyses adjusting for donor tissue characteristics, recipient age, and diagnosis, an association of borderline significance was found between higher donor age and early failure [odds ratio (95% confidence interval): 1.03 (1.00-1.05); unit change of 1 yr] and DSAEK [odds ratio 1.02 (1.00-1.04); unit of change 1 yr] cases.

CONCLUSIONS

The proportion of early graft failures in DMEK decreased over time and was comparable with failure rates in DSAEK at the end of the study period. The surgical learning curve might have played a role.

Descemet membrane endothelial keratoplasty in complex eyes

PURPOSE OF REVIEW

To review the current literature on Descemet membrane endothelial keratoplasty (DMEK) in complex eyes.

RECENT FINDINGS

DMEK surgery has become a standardized procedure in Fuchs endothelial dystrophy and simple bullous keratopathy. But eyes with more complex disease present unique intraoperative and postoperative challenges to the DMEK surgeon. Poor visualization during surgery, complex anterior segment anatomy, altered anterior chamber dynamics, glaucoma shunts, and congenital or iatrogenic missing or altered iris and lens make DMEK surgery extremely difficult to accomplish.

SUMMARY

DMEK is feasible in complex eyes, including advanced bullous keratopathy, eyes with history of glaucoma or vitreoretinal surgery, previous penetrating keratoplasty, uveitis, pediatric, and congenital anterior segment disorders. The tools and methods reported in the literature to accomplish DMEK in complex eyes vary widely with no particular consensus or standardization of techniques. The outcomes noted for some of these conditions demonstrate the difficulty of the surgery and the uncertainty of long-term graft survival in complex eyes. Both surgical standardization and randomized prospective data will better help elucidate DMEK's role in the corneal rehabilitation of complex eyes.

Risk Factors for Repeat Keratoplasty after Endothelial Keratoplasty - an IRIS® Registry Analysis

PURPOSE

To assess risk factors for repeat keratoplasty after endothelial keratoplasty (EK).

DESIGN

Retrospective cohort study METHODS: : EK procedures performed between 2013-2018 in the IRIS® Registry (Intelligent Research in Sight) were identified.

STUDY POPULATION

Patients aged 18 years and older who underwent EK.

MAIN OUTCOME MEASURES

1) Risk factors for repeat keratoplasty, and 2) complication rates after EK. A Kaplan-Meier survival analysis was used to determine the probability of repeat keratoplasty. A multivariable shared frailty survival model was used to assess risk factors.

RESULTS

59,344 procedures were identified in the registry, of which 30,600 EK procedures met the inclusion criteria for the analysis. The probability of repeat keratoplasty was 17.4% (95% CI:16.7-18.0%) at five years. Risk factors for repeat keratoplasty include post-operative re-bubbling procedure (HR 2.24, 95% CI:2.05-2.45); prior failed graft (HR 2.07, 95% CI:1.84-2.32) or bullous keratopathy (HR 1.47, 95% CI:1.33-1.61) versus Fuchs dystrophy as surgical indication; subsequent routine cataract surgery (HR 1.61, 95% CI:1.45-1.79); as well as subsequent (HR 1.53, 95% CI:1.39-1.69) and prior/concurrent (HR 1.23, 95% CI:1.11-1.36) glaucoma surgery or history of glaucoma (HR 1.24, 95% CI:1.14-1.35). Medicaid (HR 1.47, 95% CI:1.13-1.92), military/government (HR 1.29, 95% CI:1.03-1.60), Medicare Fee-for-Service (HR 1.17, 95% CI:1.05-1.31) or Medicare Managed (HR 1.17, 95% CI:1.01-1.36) insurances versus private insurance, as well as Black versus White race (HR 1.25, 95% CI:1.11-1.40) and smoking (HR 1.16, 95% CI:1.05-1.27) were also associated with an increased risk of undergoing repeat keratoplasty.

CONCLUSIONS

Black race, government-based insurance plans, and smoking were identified as independent factors associated with repeat keratoplasty in addition to history of glaucoma, glaucoma surgery, and prior graft failure or bullous keratopathy as surgical indication.

Predicting Corneal Improvement after Descemet Membrane Endothelial Keratoplasty for Fuchs Endothelial Corneal Dystrophy

PURPOSE

To develop a model to predict corneal improvement after Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial corneal dystrophy (FECD) from Scheimpflug tomography.

DESIGN

Cross-sectional study.

PARTICIPANTS

Forty-eight eyes (derivation group) and 45 eyes (validation group) with a range of severity of FECD undergoing DMEK.

METHODS

Scheimpflug images were obtained before and after DMEK. Before DMEK, pachymetry map and posterior elevation map patterns were quantified by a special image analysis program measuring tomographic features of edema (loss of regular isopachs, displacement of the thinnest point of the cornea, posterior surface depression). Image-derived novel parameters were combined with instrument-derived parameters, and the relative influences of parameters associated with the change in central corneal thickness (CCT) after DMEK in the derivation group were determined by using a gradient boosting machine learning model. The parameters with highest relative influence were then fit in a linear regression model. The derived model was applied to the validation group. Correlations and agreement were assessed between predicted and observed changes in CCT.

MAIN OUTCOME MEASURES

Predictive power (R ²) and mean difference between predicted and observed change in CCT.

RESULTS

The gradient boosting machine model identified 4 novel parameters of isopach circularity and eccentricity and 1 instrument-derived parameter (posterior surface radius); preoperative CCT was a poor predictor. In the derivation group, the model strongly predicted the change in CCT after DMEK (R ² = 0.80; 95% confidence interval [CI], 0.71-0.89) and the mean difference between predicted and observed change was, by definition, 0 μm. When the same 5 parameters were fit to the validation group, the model performed very highly (R ² = 0.89; 95% CI, 0.84-0.94). When the coefficient estimates from the derivation model were used to predict the change in CCT in the validation group, the predictive power was also high (R ² = 0.78; 95% CI, 0.68-0.88), and the mean difference was 4 μm (predicted minus observed).

CONCLUSIONS

Scheimpflug tomography maps of corneas with FECD can predict the improvement in CCT after DMEK, independent of preoperative corneal thickness measurement. The model could be applied in clinical practice or for clinical research of FECD.

Surgeons preferences in descemet membrane endothelial keratoplasty (DMEK)

AIM

To explore the attitudes, preferences, and barriers of DMEK among corneal specialists in Saudi Arabia.

METHOD

An anonymous survey was sent through an online platform to members of the Saudi Ophthalmological Society. The survey was designed to capture data covering: demographic data, practice patterns of keratoplasty techniques, DMEK technique preferences, barriers, and facilitators to performing DMEK.

RESULTS

Thirty-five (33% response rate) surgeons participated in the questionnaire. Sixty-eight percent were in practice for less than or equal to 10 years. Thirteen surgeons were performing DMEK. Participating in any training capacity was observed among surgeons who performed DMEK (92%). The main selection criteria for this procedure were patients with normal anterior chamber anatomy (77%). The main barrier against DMEK adoption among surgeons who do not perform the procedure was the lack of experience (91%). Strategies to help begin performing DMEK were eye banks support (prepared grafts, backup tissue for inadvertent loss), access to wet-lab training courses, and higher surgical volume.

CONCLUSION

DMEK is not highly performed among corneal specialists in Saudi Arabia; however, there is evident interest in adopting this technique. Strategies toward filling the gap of lacking experience would facilitate the adoption of the procedure. Eye banks play a crucial role by providing prepared tissues, which would lessen part of the technical difficulty.

Effects of Combined Cataract Surgery on Outcomes of Descemet's Membrane Endothelial Keratoplasty: A Systematic Review and Meta-Analysis

Objective

A systematic review and meta-analysis of literature-to-date regarding the effects of combined cataract surgery on outcomes of DMEK.

Methods

Multiple electronic databases were searched, including Cochrane Library databases, PubMed, Web of Science, and ClinicalTrials.gov. The final search was updated on 10th February 2022. We included randomized controlled trials (RCTs), non-randomized studies and large case series (≥25 eyes) of DMEK (pseudophakic/phakic) and “triple DMEK”. A total of 36 studies were included in this study. Meta-analyses were done with risk differences (RD) computed for dichotomous data and the mean difference (MD) for continuous data via random-effects model. Primary outcome measure: postoperative re-bubbling rate; secondary outcome measures: complete/partial graft detachment rate, best-corrected visual acuity (BCVA), endothelial cell loss (ECL), primary graft failure, and cystoid macular edema (CMO).

Results

A total of 11,401 eyes were included in this review. Based on non-randomized studies, triple DMEK demonstrated a better BCVA at 1-month postoperative than DMEK alone (MD 0.10 logMAR; 95% CI: 0.07–0.13; p < 0.001), though not statistically significant at 3–6 months postoperative (MD 0.07 logMAR; 95% CI: −0.01 to 0.15; p = 0.08). There was no significant difference in rebubbling, ECL, graft failures, and CMO postoperatively between the two groups (p = 0.07, p = 0.40, 0.06, and 0.54 respectively).

Conclusion

Our review suggests that DMEK has a similar post-operative complication risk compared to “triple DMEK” (low-quality evidence), with comparable visual outcome and graft survival rate at 6 months postoperative. High-quality RCTs specifically studying the outcomes of combined vs. staged DMEK are still warranted.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020173760, identifier: CRD42020173760.

Early intraocular pressure changes following different keratoplasty techniques and association with cornea parameters and anterior chamber depth

Background:

Corneal transplantation surgery is associated with an increased risk of intraocular pressure (IOP) elevation. Increased IOP may cause irreversible vision loss and graft failure.

Objective:

We aimed to evaluate early IOP changes following different keratoplasty techniques and to investigate the relationship between corneal thickness (CT), keratometry values, anterior chamber depth (ACD), and IOP changes.

Methods:

We included patients who underwent penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet membrane endothelial keratoplasty (DMEK) in this observational study. ACD, CT, and keratometry measurements were repeated postoperatively at hour 24, week 1, and month 1. IOP measurements were repeated at postoperative hours 6 and 24, week 1, and month 1 by Tono-Pen XL.

Results:

In total, 22 patients underwent PK, 12 patients underwent DALK, and 19 patients underwent DMEK. The difference between the IOP preoperatively and postoperatively hour 6, and between the IOP preoperatively and postoperatively hour 24 was statistically significant in the three types of surgery ( p < 0.05 for each). The difference between preoperative and postoperative week 1 IOP was statistically significant only in the PK group ( p = 0.023). When the IOP was compared between the three types of surgeries, the IOP at postoperative week 1 in the PK group was significantly higher than the DALK and DMEK groups ( p = 0.021). There was no correlation between ACD, CT, K values, and IOP in any group.

Conclusion:

IOP may increase in all types of keratoplasty during the first hours after surgery, but PK has a risk of high IOP longer in the early postoperative period. PK patients should be followed more carefully during postoperative week 1 to check for an increase in IOP.

An Overview of Intraoperative OCT-Assisted Lamellar Corneal Transplants: A Game Changer?

Intraoperative optical coherence tomography (iOCT) is a noninvasive imaging technique that gives real-time dynamic feedback on surgical procedures. iOCT was first employed in vitreoretinal surgery, but successively served as a guidance in several anterior segment surgical approaches: keratoplasty, implantable Collamer lens (ICL) implantation, and cataract surgery. Among all of those approaches, the unbeatable features of iOCT are fully exploited in anterior and posterior lamellar keratoplasty, and the purpose of this review is to focus on the advantages and shortfalls of iOCT in these techniques, in order to assess whether this technology could be a real step forward. In deep anterior lamellar keratoplasty (DALK), iOCT is useful to evaluate the needle depth into the corneal stroma, the big bubble dissection plane, and residual stromal bed, thus aiding the standardization of the technique and the reduction of failures. In Descemet stripping automated endothelial keratoplasty (DSAEK), iOCT allowed for clear visibility of fluid at the graft/host interface, allowing for immediate rescue maneuvers and granting the best graft apposition. In Descemet membrane endothelial keratoplasty (DMEK), iOCT can track the lenticule unfolding in real time and assess graft orientation even in severe hazy corneas, thus optimizing surgical times, as well as avoiding the use of potentially hazardous exterior markers (such as the “S” stamp) and preventing unnecessary manipulation of the graft. Overall, the role of iOCT appeared crucial in several complicated cases, overcoming the difficulties of poor visualization in a fast, non-invasive way, thus raising this approach as possible gold standard for challenging conditions. Further improvements in the technology may enable autonomous centering and tracking, overcoming the current constraint of instrument-induced shadowing.

650 GHz imaging as alignment verification for millimeter wave corneal reflectometry

A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing 5 off-axis parabolic mirrors, a thin film beam splitter, and 2-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off.