Patterns of corneal endothelialization and corneal clearance after descemet membrane endothelial keratoplasty for fuchs endothelial dystrophy

How Would Nature See Our Corneal Triumphs? The LXXIX Edward Jackson Lecture

PURPOSE

To describe discrepancies between clinical observation and current teachings in corneal endothelial disease, particularly in Fuchs endothelial dystrophy and its potential association with primary open angle glaucoma.

DESIGN

Perspective.

METHODS

A perspective is presented on Fuchs dystrophy, a disorder that commonly presents with a compromised endothelium but minimal stromal edema, indicating that the corneal imbibition pressure is relatively "too high."

RESULTS

The discrepancy between the relative lack of stromal edema in the absence of an endothelial cell layer cannot be explained by the current theories involving a circulatory pumping mechanism over the endothelial cell layer, but may point to the following: (1) secondary involvement of the corneal endothelium in Fuchs dystrophy; (2) separate hydration systems for maintaining the imbibition pressure (vertical static hydration) and corneal nutrition (horizontal dynamic hydration); (3) the cornea as net contributor of aqueous humor; (4) a close relationship between the corneal imbibition and intraocular pressure, with potentially a shared regulatory system; and (5) a potential steroid-type hormone dependency of this regulatory system.

CONCLUSIONS

Clinical observation shows that the stromal imbibition pressure is "too high" in Fuchs endothelial dystrophy, indicating that it may not primarily be an endothelial disease, but a type of "corneal glaucoma."

Effects of graft detachment on the central corneal thickness after uncomplicated Descemet membrane endothelial keratoplasty

PURPOSE

To determine if early central corneal thickness (CCT) and best-corrected visual acuity (BCVA) changes indicate graft detachment after uncomplicated Descemet membrane endothelial keratoplasty (DMEK).

METHODS

In this analysis of our prospectively collected ADDA registry data ( https://drks.de/search/de/trial/DRKS00027180 ), 45 pseudophakic eyes underwent DMEK surgery at the Department of Ophthalmology, RWTH Aachen University. Anterior segment optical coherence tomography (AS-OCT), the presence of stromal ripples on the posterior corneal surface, and BCVA measurements were assessed prior to, 1 day, 1 week, 1 month, and 6 months after surgery.

RESULTS

Eyes were categorized into three groups: no graft detachment (group 1) (20/45; 44.4%), < 1/3 graft detachment (group 2) (14/45; 31.1%), ≥ 1/3 graft detachment followed by rebubbling (group 3) (11/45; 24.4%). Eyes in group 3 had a greater CCT prior to (746.8 ± 95.8 µm vs. 665.0 ± 74.4 µm, P = 0.041), and 1 week (666.8 ± 119.5 µm vs. 556.5 ± 56.8 µm, P = 0.001) after DMEK compared to group 1. By 1 month, CCT in all groups aligned. Comparing prior to and 1 week after DMEK, none of the eyes in group 1 had an increase in CCT, while the CCT increased in 25.0% of eyes in group 2 and 22.2% in group 3. In group 1, 90.0% had a CCT of < 600 µm 1 week after DMEK, compared to only 50.0% in group 2 and 36.4% in group 3. In group 1, 90.0% (18/20) had an improved BCVA 1 week after DMEK, while in groups 2 and 3, 86.7% (12/14) and 18.2% (2/11) improved, respectively. One patient in group 3 showed posterior stromal ripples 1 day and 1 week after DMEK.

CONCLUSION

If 1 week after uncomplicated DMEK CCT is < 600 µm and has decreased from before surgery, BCVA has improved, and there are no posterior stromal ripples, a graft detachment ≥ 1/3 and the need for rebubbling are very unlikely. In all other cases, meticulous slit-lamp and OCT inspection of the peripheral graft for detachments should be advised.

Incidence and management of early postoperative complications in lamellar corneal transplantation

PURPOSE

To provide a comprehensive review of the incidence, risk factors, and management of early complications after deep anterior lamellar keratoplasty (DALK), Descemet stripping automated keratoplasty (DSAEK), and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

A literature review of complications, that can occur from the time of the transplant up to 1 month after the transplant procedure, was conducted. Case reports and case series were included in the review.

RESULTS

Complications in the earliest postoperative days following anterior and posterior lamellar keratoplasty have shown to affect graft survival. These complications include, but are not limited to, double anterior chamber, sclerokeratitis endothelial graft detachment, acute glaucoma, fluid misdirection syndrome, donor-transmitted and recurrent infection, and Uretts-Zavalia syndrome.

CONCLUSION

It is essential for surgeons and clinicians to not only be aware of these complications but also know how to manage them to minimize their impact on long-term transplant survival and visual outcomes.

Rebubbling and graft detachment in Descemet membrane endothelial keratoplasty using a standardised protocol

OBJECTIVES

To analyse risk factors and long-term outcomes after rebubbling and graft detachment in Descemet membrane endothelial keratoplasty (DMEK).

METHODS

176 consecutive DMEK grafts of 125 patients performed by 8 surgeons with a standardised technique between January 2015 and July 2022 were analysed. Main outcome measures were graft detachments, rebubbling rate, postoperative outcomes, and risk factors for graft failure and rebubbling.

RESULTS

6 (3.4%) grafts required rebubbling (>1/3 area detached). 40 (22.7%) grafts developed self-resolving partial detachments (<1/3 area detached). The mean time to rebubble was 16 ± 9.4 days. Mean BSCVAs at 5 years postoperative were 0.03 ± 0.16, 0.03 ± 0.14, and 0.15 ± 0.31 logMAR in fully attached, partially detached and rebubbled grafts (P = 0.437). 5-year graft survival were 98%, 90%, and 83% in fully attached, partially detached and rebubbled eyes (P = 0.02). There was significantly greater endothelial cell loss (ECL) in the rebubbled eyes (P = 0.018). Intraoperative trauma was a risk factor for graft failure (HR 1.81; 95% CI: 1.33-2.50; P = 0.023). An indication for surgery other than Fuchs endothelial dystrophy was a risk factor for rebubbling (HR 5.28; 95% CI: 5.11-72.4; P = 0.007).

CONCLUSION

DMEK grafts had better graft survival if there was no partial detachment or rebubbling at 5 years postop. There was significant ECL associated with rebubbling. A standardised technique reduces rebubbling and graft failure risk.

Spontaneous corneal clearance after graft detachment in DMEK

Descemet Membrane detachment is a potential complication after Descemet Membrane Endothelial Keratoplasty (DMEK). Here, we present a unique case of a DMEK surgery in a complicated eye that suffered a nearly complete DMEK graft detachment and later a graft opacification with a pseudo-anterior chamber. In Mid-November 2020, a planned DMEK was performed in a 64-year-old male patient due to corneal decompensation. Four months after DMEK, a fibrotic DMEK graft was seen across the anterior chamber with a pseudo-anterior chamber; however, the recipient cornea showed complete clearance with an endothelial cell count of about 1204 cells/mm2 and a best-corrected visual acuity of 20/25. Three months later, we observed a significant opacification of the detached graft, and the best-corrected distance visual acuity decreased to 20/63. We proceeded with the graft removal without performing a second DMEK. Ten months after graft removal, the cornea remained clear with an endothelial cell count of about 510 cells/mm², and the best-corrected visual acuity was 20/25.

Establishing a Biomarker for the Prediction of Short-Term Graft Detachment After Descemet Membrane Endothelial Keratoplasty

PURPOSE

The purpose of this study was to investigate the predictive value of pachymetry mapping 1 day after Descemet membrane endothelial keratoplasty (DMEK) as a biomarker for early graft detachment.

METHODS

This was a post hoc analysis of 65 pseudophakic subjects with Fuchs endothelial dystrophy who underwent DMEK surgery between December 2018 and April 2021 as part of the Advanced Visualization In Corneal Surgery Evaluation international multicenter randomized controlled trial. One eye per patient was included. Preoperatively and 1 day postoperatively, patients underwent anterior segment optical coherence tomography imaging. Using a grid consisting of 25 zones (ie, pachymetry map), corneal thickness and presence of a graft detachment were mapped for each patient. Detachments of any size were considered, regardless of subsequent clinical interventions. Missing data were imputed and subsequently divided into a training and test set. Two prediction methods were evaluated: one model based on absolute corneal thickness and a regression model.

RESULTS

A total of 65 eyes were included for analysis of which 33 developed any form of graft detachment. Preoperatively, no significant differences were observed between the groups ( P = 0.221). Corneal thickness in the corneal zones with a detached graft was significantly increased compared with corneal zones with an attached graft ( P < 0.001). The regression prediction model had an area under the curve of 0.87 (sensitivity: 0.79 and specificity: 0.75), whereas the absolute thickness cutoff model only reached 0.65.

CONCLUSIONS

Pachymetry mapping 1 day after DMEK was predictive for early graft detachment, and the prediction model had a good to excellent performance. This aids in identifying patients at risk for graft detachment and subsequent tailored postoperative care.

Predictive factors of graft detachment and rebubbling after descemet membrane endothelial keratoplasty

PURPOSE

To identify risk and predictive factors associated with the need of rebubbling in the eye of patients who underwent a descemet membrane endothelial keratoplasty (DMEK).

METHODS

The records of patients who underwent DMEK were retrospectively analyzed. Data regarding comorbidities, intraoperative characteristics, and postoperative treatments or complications were collected. The central corneal thickness (CCT) was measured by optical coherence tomography before and the day after DMEK. Univariate and multivariate analyses were performed.

RESULTS

Of the 333 DMEK, rebubbling was performed in 119 cases (36%). Preoperative subepithelial fibrosis and a history of penetrating keratoplasty (PK) were associated with significantly more graft detachment [OR of 3.55 (2.02-6.32; P < 0.001) and 5.89 (2.00-21.86; P = 0.003), respectively]. A decreased CCT the day after surgery reduced by 5.7-fold the risk of rebubbling (sensitivity/specificity of 0.42/0.93). Conversely, a 20% increase in the CCT the day after surgery increased by 4.5-fold the risk of rebubbling (sensitivity/specificity of 0.42/0.91).

CONCLUSION

Variation of the CCT could be used as a predictive factor of rebubbling after DMEK. Patients with a 20% increase of CCT the day after surgery are at higher risk of graft detachment. Conversely, a reduced CCT the day after the surgery is associated with a reduced risk of rebubbling. Subepithelial fibrosis and history of PK were also identified as risk factors for rebubbling. Those predictive factors may help develop a customized approach for patients undergoing DMEK surgery.

Deep Anterior Lamellar Keratoplasty with Large Descemet's Membrane Perforation: Should We Stop Conversion to Penetrating Keratoplasty?

Purpose

To evaluate the outcome of eyes with large Descemet's membrane (DM) perforation during deep anterior lamellar keratoplasty (DALK).

Methods

A retrospective, interventional case series of 12 eyes with completed DALK, despite DM perforation larger than 4 mm in its widest dimension. The main outcome measures included graft clarity, endothelial cell density (ECD), corrected distance visual acuity (CDVA), and DM detachment.

Results

The mean age of patients was 26.8 ± 11.4 years. Preoperative pathology included keratoconus (n = 10), macular dystrophy (n = 1), and postmicrobial keratitis corneal scar (n = 1). The average size of DM perforation was 6.5 mm ± 1.3 mm. At the end of the follow-up period (median 15 months, range 6-53 months), the mean CDVA was 0.32 ± 0.09 logMAR and the mean ECD was 1830.8 ± 299.7 cells/mm². Nine patients (75%) developed DM detachments postoperatively and was managed by intracameral air injection once in six eyes, and twice in three eyes. Other complications included persistent localized stromal edema at the site of DM defect in one eye and Urrets Zavalia syndrome in one eye.

Conclusion

Completing DALK in eyes with large DM perforation provides good visual acuity, endothelial cell count and may be superior to penetrating keratoplasty regarding long-term graft survival if confirmed in future comparative studies.

Endothelial Cell Density Changes in the Corneal Center Versus Paracentral Areas After Descemet Membrane Endothelial Keratoplasty

PURPOSE

To analyze whether endothelial cell density (ECD) differs between central and paracentral areas after Descemet membrane endothelial keratoplasty (DMEK) and to identify the locations of the highest and lowest ECD.

METHODS

In this retrospective cohort study, central and paracentral ECDs of 30 eyes of 30 patients who underwent DMEK for Fuchs endothelial corneal dystrophy were evaluated. Central, superonasal, superotemporal, and inferior specular microscopic images were analyzed at 1, 3, 6, 9, and 12 months after DMEK. Changes in ECD by location and over time and changes in location for the highest and lowest ECD were evaluated.

RESULTS

When compared with the preoperative donor ECD, the central ECD decreased by 32 (±11)% at 12 months postoperatively. ECD decline between 1 and 12 months postoperatively in the central, inferior, superonasal, and superotemporal location were 7%, 12%, 16%, and 13%, respectively (P < 0.0001 for all locations). Mean ECD was the highest in the center between the 3- to 12-month follow-up, whereas mean ECD was the lowest in the paracentral superonasal area at all time points (P < 0.001). Mean ECD of the highest and lowest density locations differed at all follow-up time points (P < 0.003).

CONCLUSIONS

Postoperative ECD was not found to be uniform across the graft. Contrary to the density distribution in the normal endothelium, paracentral area ECDs were found to be consistently lower than in the central area. These differences were most prominent in the superonasal area and persisted 12 months postoperatively. Central ECD after DMEK might, thus, not represent an accurate proxy for cell density of the entire graft.

Risk Factors for Repeat Descemet Membrane Endothelial Keratoplasty Graft Failure

PURPOSE

To evaluate repeat Descemet membrane endothelial keratoplasty (re-DMEK) success rates and to identify risk factors for re-DMEK failure.

DESIGN

Retrospective case series.

METHODS

Settings: Institutional.

PATIENTS AND INTERVENTIONS

A chart review was performed, including all eyes with primary DMEK failure that underwent re-DMEK between 2013 and 2019 at the Toronto Western Hospital and the Kensington Eye Institute (Toronto, Ontario, Canada) and had at least 6 months of follow-up.

MAIN OUTCOME MEASURE

Predicting factors for re-DMEK outcome.

RESULTS

Of 590 consecutive DMEK surgeries, 40 eyes (6.7%) were identified for having a secondary DMEK surgery after primary DMEK failure. Etiologies for primary DMEK were Fuchs endothelial corneal dystrophy (32.5%), pseudophakic bullous keratopathy (35%), previous failed graft (27.5%), and other indications (5%). Fifty-five percent of the cohort were categorized as having a complicated anterior segment including 11 eyes with previous glaucoma surgery, 7 eyes post-penetrating keratoplasty, 4 eyes post-Descemet stripping automated endothelial keratoplasty, 3 eyes peripheral anterior synechia, 3 eyes previous pars plana vitrectomy, 2 eyes aphakia, and 1 eye each with aniridia, anterior chamber intraocular lens, and iris-fixated intraocular lens. Re-DMEK failure was documented in 12 eyes (30%) of the entire cohort. The risk factor for re-DMEK failure was the presence of a complicated anterior segment (P = .01, odds ratio = 17.0 [95% confidence interval: 1.92-150.85]), with 50% re-DMEK failure rate in this subgroup.

CONCLUSION

Re-DMEK is a viable option for cases of primary DMEK failure, especially for eyes with Fuchs endothelial corneal dystrophy as the indication for primary DMEK without other ocular morbidities; however, eyes categorized with a complicated anterior segment had high re-DMEK failure rates.</ABSTRACT>.

Potential Functional Restoration of Corneal Endothelial Cells in Fuchs Endothelial Corneal Dystrophy by ROCK Inhibitor (Ripasudil)

PURPOSE

Rho-associated kinase (ROCK) inhibitors have been successfully used as a rescue strategy in eyes that failed to clear after descemetorhexis without endothelial graft for treatment of Fuchs endothelial corneal dystrophy (FECD). The functional mechanisms by which ROCK inhibitors modulate corneal endothelial cell regeneration in FECD patients have, however, not been clarified. Here, we analyzed the effect of the ROCK inhibitor ripasudil on corneal endothelial cells of FECD patients and normal donors using ex vivo tissue and in vitro cellular models.

DESIGN

Experimental study: laboratory investigation.

METHODS

This institutional study used endothelial cell-Descemet membrane lamellae from FECD patients (n = 450) undergoing Descemet membrane endothelial keratoplasty (FECD ex vivo model), normal research-grade donor corneas (n = 30) after scraping off central endothelial cells (ex vivo wound healing model), normal donor corneas (n = 20) without endothelial injury, and immortalized cell lines (n = 3) generated from FECD patients (FECD in vitro model). Descemet membrane lamellae were dissected into halves and incubated for 24-72 hours in storage medium with or without a single dose of 30 μM ripasudil. The effects of ripasudil on expression of genes and proteins related to endothelial cell proliferation, migration, functionality, and endothelial-to-mesenchymal transition were analyzed and complemented by functional assays on FECD cell lines.

RESULTS

A single dose of ripasudil induced significant upregulation of genes and proteins related to cell cycle progression, cell-matrix adhesion and migration, as well as endothelial barrier and pump function up to 72 hours, whereas classical markers of endothelial-to-mesenchymal transition were downregulated in both FECD and normal specimens compared to unstimulated controls ex vivo. In addition to stimulation of proliferation and migration, ripasudil-induced changes in expression of functional signature genes could be also verified in FECD cell lines in vitro.

CONCLUSIONS

These data support the concept that inhibition of ROCK signaling represents a potent tool in regenerative therapies in FECD patients through reactivation of cell proliferation and migration as well as restoration of endothelial pump and barrier function without inducing adverse phenotypic changes.

Re-Endothelialization of Bare Stroma after Descemet's Detachment due to Macroperforation during Deep Anterior Lamellar Keratoplasty

Purpose

To report a case with spontaneous re-endothelialization of bare stroma after subtotal detachment of Descemet's membrane (DM) due to macroperforation during deep anterior lamellar keratoplasty (DALK).

Methods

Case report.

Results

A 64-year-old patient underwent DALK for deep stromal scarring secondary to herpetic keratitis. During manual dissection, DM macroperforation occurred, and this was successfully managed intraoperatively and postoperatively. The DM with host posterior stroma remained attached for 10 months when it detached from the bare donor stroma. The cornea remained clear, with uncorrected distance visual acuity (UCVA) of 0.17 logMAR. After graft suture removal 30 months later, he was noted to have regular astigmatism and cataract for which he underwent phacoemulsification with toric intraocular lens implantation. Twenty-four months following his cataract surgery and 58 months following his DALK, his UCVA remains 0.17 logMAR and the cornea remains clear with no evidence of edema. His average specular count at 58 months was 1296 cell/mm² .

Conclusion

This case shows a very good visual outcome with clear cornea at 58 months despite of large DM detachment which happened 10 months following manual DALK with intraoperative macroperforation.

Ex vivo excimer laser ablation of cornea guttata and ROCK inhibitor-aided endothelial recolonization of ablated central cornea

PURPOSE

To determine whether excimer laser ablation of guttae is a viable strategy for removal of diseased tissue in Fuchs' endothelial corneal dystrophy (FECD) on excised human Descemet membranes and whether an excimer laser-created wound on healthy human corneas ex vivo is recolonized with corneal endothelial cells.

METHODS

Descemet membranes of FECD patients and corneal endothelium of normal human corneas were ablated ex vivo using an excimer laser licensed for glaucoma surgery. Specimens were kept in cell culture medium supplemented with 10 μm of rho-kinase inhibitor ripasudil. Corneal endothelial cell regeneration was observed using light and electron scanning microscopy. Furthermore, the whole corneal samples were evaluated by haematoxylin/eosin staining and immunohistochemical analysis using antibodies against Na⁺ /K⁺ -ATPase.

RESULTS

Guttae and corneal endothelium could be ablated with an excimer laser without total ultrastructural damage to the Descemet membrane or stroma. Nearly complete endothelial wound closure was accomplished after 26-38 days in treated corneas. Light and electron scanning microscopy suggested the establishment of a layer of flat endothelial cells. Additionally, Na⁺ /K⁺ -ATPase expression could only be observed on the inner side of the Descemet membrane.

CONCLUSION

Our proof of concept study demonstrated that excimer lasers can be used to ablate diseased tissue from excised FECD Descemet membranes ex vivo. Additionally, corneal endothelial cells recolonize a previously ablated endothelial area in healthy human corneas ex vivo under treatment with ripasudil. Thus, our results are the first experimental basis to further investigate the feasibility of an excimer laser ablation as a graftless FECD treatment option.

The Cologne rebubbling study: a reappraisal of 624 rebubblings after Descemet membrane endothelial keratoplasty

Background/Aims

To analyse graft detachments prior to rebubbling, the influence of rebubbling on the postoperative outcome after Descemet membrane endothelial keratoplasty (DMEK) and the need for rebubbling on the contralateral eye.

Methods

In this retrospective cohort study, out of 1541 DMEKs, optical coherence tomography scans and clinical records of 499 eyes undergoing rebubbling after DMEK at the University Hospital of Cologne, Cologne, Germany, were examined. Main Outcome measures were (a) number, localisation and size of graft detachments; (b) influence of rebubbling/s on postoperative outcome after 12 months; and (c) rebubbling risk of the contralateral eye after DMEK.

Results

Mean number of detachment areas was 2.02±0.9. Mean lateral diameter of all detachments was 4534.76±1920.83 μm. Mean axial diameter was 382.53±282.02 μm. Detachments were equally distributed over all regions of the cornea. Best spectacle corrected visual acuity ( BSCVA) after 12 months was 0.197±0.23 logarithm of the minimum angle of resolution, endothelial cell density (ECD) was 1575.21±397.71 cells/mm2and mean central corneal thickness (CCT) was 566.37±68.11 μm. BSCVA, CCT, ECD or endothelial cell loss of all rebubbled patients were not influenced by the number of rebubblings or the time between DMEK and rebubbling. Of the rebubbled patients, which received a DMEK subsequently on the other eye, 193 (58.8%) also received a rebubbling, which was significantly higher, when compared to the overall rebubbling rate of 32.3% (p=0.000).

Conclusions

The overall number of rebubblings has no influence on the postoperative outcome after DMEK, if a rebubbling becomes necessary. Patients who received a rebubbling on one eye have an elevated risk for a rebubbling on the fellow eye.

Regenerative medicine in Fuchs' endothelial corneal dystrophy

The management of Fuchs' endothelial corneal dystrophy (FECD) has evolved rapidly since the introduction of endothelial keratoplasty (EK). In recent years, advances in our understanding of endothelial cell biology, in particular with respect to the regenerative capacity of endothelial cells, have opened the door to novel therapeutic options that stray from the traditional paradigm of allograft transplantation. We review the development of descemetorhexis without EK (DWEK) as a primary treatment for FECD and discuss the lessons learned to date about the mechanism of wound healing, surgical technique, patient selection, and refractive outcomes. Multiple randomized clinical trials are currently underway to evaluate the potential for pharmacological supplementation with rho-associated kinase inhibitors to increase the success rate of corneal clearance following DWEK. Biologic supplementation with intracameral endothelial cell injection and acellular Descemet's membrane transplantation are other avenues of adjuvant therapy. DWEK is a promising surgical option for management of a subset of FECD patients.

Factors associated with endothelial cell density loss post Descemet membrane endothelial keratoplasty for bullous keratopathy in Asia

PURPOSE

To investigate the factors associated with endothelial survival after Descemet's membrane endothelial keratoplasty (DMEK) in eyes of Asian patients with bullous keratopathy (BK).

METHODS

In this retrospective, consecutive interventional case series, 72 eyes of 72 patients who underwent DMEK were evaluated. Best corrected visual acuity (BCVA) and corneal endothelial cell density (ECD) were assessed at 12 months postoperatively. Multiple regression analysis was performed to assess parameters such as age, sex, axial length, preoperative visual acuity, re-bubbling, the ratio of graft to cornea area, iris damage scores, types of filling gases, air or SF6 volume in the anterior chamber (AC) on postoperative day 1, and ECD loss rates at 12 months postoperatively.

RESULTS

BCVA improved significantly at 12 months after DMEK (P < .001). The rate of ECD loss at 12 months after DMEK was 54.4 ± 16.1%. Multiple linear regression analysis showed that a larger ratio of graft to corneal area (P = 0.0061) and higher donor ECD (P = 0.042) were the primary factors for a lower ECD loss rate at 12 months after DMEK.

CONCLUSION

A relatively larger graft size compared to the host cornea and more donor ECD might help endothelial survival in patients with BK. Moreover, for such patients, the surgeon should attempt to use a relatively larger graft size when performing DMEK, particularly in Asian eyes.

Establish an In Vitro Cell Model to Explore the Impacts of UVA on Human Corneal Endothelial Wound Healing

PURPOSE

To provide scientific data for clinical practice in making strategies for accelerating corneal endothelial wound healing, we investigated the impact of UVA on the corneal endothelial wound healing process and the underlying mechanism using an in vitro cell model.

MATERIALS AND METHODS

An in vitro cell model for corneal endothelial wound healing was established by scratching the in vitro cultured human corneal endothelial cell (HCEnC) confluent layer. Then, we investigated the impacts of UVA irradiation and Ascorbic acid-2-phosphate (Asc-2p) on the wound healing process of the in vitro HCEnC model by examining wound-healing index, F-actin⁺ rate, Ki-67⁺ rate, and ROS production.

RESULTS

After scratching, the Ki-67⁺ and F-actin⁺ HCEnCs occupied the scratching gap. Furthermore, the F-actin⁺ rates were significantly higher than Ki-67⁺ rates in the wound closure area. After irradiated with UVA, the wound-healing indexes, Ki-67⁺ rates and F-actin⁺ rates of the wound-healing model significantly reduced, whereas the ROS production significantly increased in a dose-dependent manner. Pretreatment with Asc-2p significantly reduced the ROS production as well as increased the wound-healing indexes, Ki-67⁺rates and F-actin⁺ rates of the UVA irradiated wound-healing model.

CONCLUSION

The migration of HCEnC plays a major role in the wound healing process of the established cell model, which is like the wound healing process in vivo. UVA decreases the wound closure of the in vitro HCEnC model dose-dependently, while antioxidant Asc-2p can attenuate the damage to UVA to HCEnCs probably via reducing ROS to improve their migration.

The Rapid Transformation of Transplantation for Corneal Endothelial Diseases: An Evolution From Penetrating to Lamellar to Cellular Transplants

The cornea is the major focusing structure of the human eye and the corneal endothelium maintains the relatively dehydrated state of the cornea required for clarity. The endothelial cells respond to disease or injury by migration and cellular enlargement. Our current understanding is that there is a very limited degree of proliferative or regenerative capacity in the human corneal endothelium. Thus, corneal endothelial diseases may result in corneal edema, significantly impact vision and quality of life. Contemporary surgical transplantation options for treating moderate to advanced endothelial dysfunction include penetrating keratoplasty (PK), Descemet stripping endothelial keratoplasty (DSEK), and Descemet membrane endothelial keratoplasty. Advances in surgical techniques aim to bring faster visual recovery and improve visual outcomes; however, there is still a significant donor cornea shortage worldwide and alternative methods for treatment for corneal endothelial disease are rapidly evolving. Indeed, we are at a pivotal point in corneal transplantation for endothelial disease and novel surgical strategies include using 1 donor for multiple recipients, a minimally attached endothelial graft, and Descemet membrane stripping only. Crucially, forthcoming approaches include the use of Rho-Kinase (ROCK) inhibitors, endothelial cell therapy, tissue engineered grafts, and consideration of stem cell techniques. Ultimately, the choice of technique will be dependent on recipient factors such as age, type of endothelial disease, extent of the disease, and associated ocular disorders. The safety and efficacy of these rapidly developing treatments warrant further investigations. In time, some or all of these alternatives for corneal transplantation will alleviate the reliance on limited corneal donor tissue.

Corneal clearance and central endothelial cell repopulation despite graft detachment after Descemet membrane endothelial keratoplasty

Objective: Descemet membrane endothelial keratoplasty (DMEK) is the gold standard procedure for treatment of primary corneal endothelial disorders. Graft detachment is a frequent complication of DMEK, which often requires re-operation or re-bubbling. However, several cases of spontaneous corneal clearance despite graft detachment after DMEK have been reported. The underlying mechanisms of this phenomenon are poorly understood. We report three cases of corneal clearance after graft detachment in patients with Fuchs endothelial dystrophy and provide a review of the literature.

Methods: An 81-year-old and a 69-year-old phakic patient as well as a 56-year-old pseudophakic patient with Fuchs endothelial dystrophy underwent Triple-DMEK and DMEK, respectively. All three patients presented postoperatively with blurred vision due to an almost complete detachment of the graft, as shown by slit-lamp photography and anterior segment optical coherence tomography (OCT).

Results: Without additional intervention, gradual corneal clearance and presence of endothelial cells on the posterior recipient’s stroma were observed in all patients three months postoperatively. Increase in endothelial cell density, decrease in central corneal thickness (CCT), recovery of corneal transparency, and improvement of visual acuity were documented in all patients.

Conclusions: Our findings support the theory of corneal clearance after Descemet membrane endothelial transfer (DMET) (“free-floating” donor Descemet graft in the recipient anterior chamber after descemetorhexis). Further understanding on endothelial homeostasis might lead to innovative approaches in handling endothelial disorders.

[Transplantation of endothelium and Descemet's membrane]

Nowadays, endothelial keratoplasty has become an alternative to penetrating keratoplasty (PKP) in the management of corneal endothelial dysfunction. Descemet membrane endothelial keratoplasty (DMEK) is a relatively new corneal transplantation surgery technique suited for patients with endothelial insufficiency, an increasing number of surgeons are learning the graft preparation technique and the surgery itself after seeing its excellent postoperative visual outcomes and faster rehabilitation of patients. DMEK has significant advantages in comparison with automated and manual Descemet Stripping Endothelial Keratoplasty (DSAEK/DSEK) and PKP including lower risk of immunologic graft rejection (1-2%), lower cost of the procedure, and it does not require expensive equipment such as a microkeratome or a femtosecond laser device. Another advantage is that the corneal graft tissue can be used for several recipients - e.g. when the Descemet's membrane and endothelium are used for a patient with endothelial dysfunction of the cornea, the retained stroma and epithelium can be then used for another patient with pathology of these corneal layers. Key problematic issues regarding this surgery are the technical difficulties during graft preparation and during surgery itself, however the majority of surgeons report very good results after gaining some experience. The article reviews latest clinical trials on DMEK and describes its strengths and weaknesses.

Histopathology of Failed Descemet Membrane Endothelial Transfer

OBJECTIVES

To describe the postmortem histologic features after an unsuccessful Descemet membrane endothelial transfer (DMET) and assess any potential clinical implications.

METHODS

Postmortem, an eye from a patient who previously underwent unsuccessful DMET for pseudophakic bullous keratopathy (PPBK) was harvested and processed for morphologic evaluation.

RESULTS

Clinically and histologically, the host cornea showed evidence of diffuse stromal edema. Although the edges of the surgical descemetorhexis were well visualized, there was no evidence of endothelial migration or repopulation of the posterior stroma from any direction. A multilayered, retrocorneal membrane was present that appeared to originate from the trabecular meshwork.

CONCLUSIONS

Descemet membrane endothelial transfer and "descemetorhexis alone" may be insufficient treatment for eyes operated on for PPBK, that is, eyes with a significantly depleted or dysfunctional endothelium.

Outcomes of ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) performed in eyes with failure of primary Descemet membrane endothelial keratoplasty (DMEK)

AIM

To evaluate the outcomes of ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK) performed in eyes after failure of primary Descemet membrane endothelial keratoplasty (DMEK).

METHODS

This was a retrospective, non-comparative interventional case series done in a tertiary care hospital. The study group included 21 eyes of patients which underwent UT-DSAEK following the failure of primary DMEK. Outcome measures included best spectacle-corrected visual acuity (BSCVA) and endothelial cell density (ECD) both recorded 6 and 12 months postoperatively as well as central graft thickness (CGT) measured 6 months after UT-DSAEK.

RESULTS

When considering only eyes without comorbidities (17 of 21), 12 months after UT-DSAEK, BSCVA was ≥20/25 in 12/13 (92%) eyes and ≥20/20 in 4/13 (30%) eyes. Mean ECD loss rate was 38.9% at 12 months postoperatively (range 8%-57%). Six months postoperatively, CGT averaged at 81±34 µm (range 34-131 µm). No intraoperative complications were recorded. Postoperatively, one patient (no. 8) had graft wrinkles that were fixed 2 days following UT-DSAEK. Four patients have developed intraocular lens (IOL) opacification, and two of them underwent IOL exchange. No other postoperative complications were recorded.

CONCLUSIONS

UT-DSAEK is instrumental in the management of primary DMEK graft failure, allowing visual rehabilitation which is comparable with that of repeat DMEK.

Evolving therapies for Fuchs' endothelial dystrophy

Fuchs' endothelial dystrophy (FED) is characterized by corneal endothelial dysfunction and guttate excrescences on the posterior corneal surface, and is the leading indication for corneal transplantation in developed countries. In severe cases, keratoplasty is considered as the gold standard of treatment. However, there have been significant developments in our understanding of FED over the past decade. Attempts have been made to treat this disease with regenerative therapy techniques such as primary descemetorhexis without an endothelial graft or with a tissue-engineering approach. The discovery of a strong association between the CTG18.1 trinucleotide repeat expansion sequence and FED may pave the way for gene therapy strategies in the future. In this review, we evaluate these novel therapeutic modalities as possible alternatives to keratoplasty as the standard of care for FED.

Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK) for Fuchs endothelial corneal dystrophy: 6 months clinical outcome

Background/aim

To assess the clinical outcome of the first series of Quarter-Descemet membrane endothelial keratoplasty (Quarter-DMEK), a potential hybrid technique between ‘descemetorhexis only’ and conventional, circular DMEK.

Methods

Prospective interventional case series at a tertiary referral centre. Twelve eyes of 12 patients with central Fuchs endothelial corneal dystrophy underwent Quarter-DMEK, that is, transplantation of one quadrant of a full-diameter DMEK graft, and were evaluated for best-corrected visual acuity (BCVA), endothelial cell density (ECD) and complications up to 6 months postoperatively.

Results

At 6 months postoperatively, all eyes reached a BCVA of ≥20/40 (≥0.5), 11/12 (92%) of ≥20/25 (≥0.8) and 6/12 (50%) of ≥20/20 (≥1.0). Mean central ECD decreased from 2867 (±161) cells/mm2 before to 1255 (±514) cells/mm2 at 1 month, 1058 (±455) cells/mm2 at 3 months and 968 (±427) cells/mm2 at 6 months after surgery. Rebubbling was performed in 4/12 eyes (33%) within the first two months.

Conclusions

Quarter-DMEK may be a feasible procedure that allows for visual outcomes similar to conventional, circular DMEK. The relatively large drop in ECD within the first month may have resulted from more extensive endothelial cell migration and/or measurement error (at the graft edges). If longer-term outcomes would resemble those of conventional DMEK, Quarter-DMEK may potentially quadruple the availability of endothelial grafts.

Two-Year Refractive Outcomes After Descemet Membrane Endothelial Keratoplasty

PURPOSE

To monitor refractive changes after Descemet membrane endothelial keratoplasty (DMEK) and to determine what may influence these changes and the time point of stabilization.

METHODS

From 67 pseudophakic DMEK eyes operated on for Fuchs endothelial dystrophy at a tertiary referral center, biomicroscopy, visual acuity, subjective refraction, and Scheimpflug-based corneal tomography data were obtained before and up to 2 years postoperatively. Visual acuity and changes in spherical equivalent (SE), mean anterior and posterior simulated keratometry (Km), and central pachymetry were analyzed.

RESULTS

At 3 months postoperatively, both hyperopic (28/67 eyes) and myopic (21/67 eyes) shifts were observed; 18/67 eyes showed no SE change. The mean change in SE at 3 months was +0.33 diopters (D) (95% confidence interval = [0.11, 0.54], P = 0.028), which stabilized thereafter (P > 0.466). Initial flattening of mean anterior Km by 0.66D (95% confidence interval = [-0.81, -0.51], P < 0.001) at 3 months was followed by a slow steepening, which became significant between 1 and 2 years postoperatively (P < 0.001). Posterior Km stabilized after 3 months (P > 0.252). Preoperative to 3 months postoperative absolute changes in anterior Km were positively related to preoperative backscattered light from the central anterior cornea (P = 0.035), and the presence of partial graft detachment postoperatively (P = 0.013).

CONCLUSIONS

After DMEK, SE and posterior corneal curvature were on average stable at 3 months after surgery, whereas the mean anterior corneal curvature showed an ongoing gradual change. Changes in anterior corneal curvature may be related to preoperative anterior corneal densitometry or postoperative partial graft detachment.

A review of the evidence for in vivo corneal endothelial regeneration

Human corneal endothelium has long been thought to be a nonmitotic cell layer with no endogenous reparative potential. Pathologies that damage endothelial function result in corneal decompensation and, if untreated, blindness. The mainstay of treatment involves partial or complete corneal replacement, amounting to 40% of all corneal transplants performed worldwide. We summarize the case reports describing complications postoperatively in the form of (sub)total graft detachment and those resulting in postoperative bare stroma. Complications during cataract and glaucoma surgeries leading to an uncovered posterior cornea are also included. We discuss the newer treatment strategies that are alternatives for current Descemet membrane endothelial keratoplasty and Descemet stripping automated endothelial keratoplasty, including partial grafts and stripping of the diseased cell layer. In more than half of the cases reviewed, corneal transparency returned despite incomplete or no corneal endothelial cell transplantation. We question the existing paradigm concerning corneal endothelial wound healing in vivo. The data support further clinical study to determine the safety of simple descemethorexis in central endothelial pathologies, such as Fuchs endothelial corneal dystrophy, where presence of healthy peripheral cells may allow successful corneal recompensation without the need for donor cells.

Graft detachment and rebubbling rate in Descemet membrane endothelial keratoplasty

Descemet membrane endothelial keratoplasty (DMEK) is a selective replacement of dysfunctional endothelium with healthy donor Descemet membrane and endothelium. Although the donor preparation and surgical methods still remain a challenge, DMEK is gaining popularity in terms of early rehabilitation and visual outcomes. New and improved donor preparation techniques like prestripped DMEK tissues are being taken up rapidly because of less manipulation that is required in the surgical theatre. Donor graft delivery in the recipient eye has also been improved because of new products like prestripped and preloaded membranes. As DMEK is at its budding stage, only early outcomes have been known so far. Early graft detachment, rebubbling rates, and primary failures are still being studied in DMEK. As there are different techniques that are currently used for preparation and injection of the graft, it becomes difficult to judge the results based on specific inclusion and exclusion criteria. Graft detachment and rebubbling rates have been a huge challenge both during the surgery and also while reporting postoperative data. We highlight the importance of defining graft detachment and rebubbling rates and their surgical relevance, which may also have an impact on graft preparation and insertion techniques.

Sex Chromosome Analysis of Postmortem Corneal Endothelium After Sex-Mismatch Descemet Membrane Endothelial Keratoplasty

PURPOSE

To identify the origin of corneal endothelial cells (host or donor) present on grafts at various time points after Descemet membrane endothelial keratoplasty (DMEK), using fluorescence in situ hybridization (FISH) of sex chromosomes on post mortem corneas with sex mismatch between the donor and host.

METHODS

Corneoscleral buttons of 6 post mortem DMEK eyes of 4 patients, operated for Fuchs endothelial dystrophy, with an average postoperative time of 2.6 (±1.8) years (range, 7 months-4.5 years), of 2.5 (±1.7) years (range, 7 months-4 years), were processed for FISH detection of XX (female) or XY (male)-labeling signals in corneal endothelial cells in the central area of the DMEK graft. Two male patients underwent bilateral DMEK with grafts from female donors, and 2 female patients underwent unilateral DMEK and received a graft from a male donor.

RESULTS

FISH consistently showed the presence of donor endothelial cells across the graft area, with signaling of sex chromosomes opposite to the sex of the host.

CONCLUSIONS

Donor endothelial cells may survive up to 4.5 years after DMEK. If so, the lower incidence of allograft rejection in DMEK may not be explained by early host cell replacement. Potential host cell migration may be limited by donor/recipient cell-cell contact inhibition.

[Descemetectomy : An alternative to transplantation?]

Due to rising demand worldwide it is becoming increasingly more difficult to satisfy the needs for human corneal transplants. At this point transplantation is the only possible cure for endothelial diseases, such as Fuchs endothelial dystrophy. In this article we present descemetectomy, a circumscribed removal of Descemet's membrane (DMx) without subsequent transplantation, as new possible treatment option on the basis of a clinical case.

[Influence of 20 % sulfur hexafluoride (SF6) on human corneal endothelial cells : An in vitro study]

BACKGROUND

In posterior lamellar keratoplasties, such as Descemet membrane endothelial keratoplasty (DMEK) and Descemet's stripping automated endothelial keratoplasty (DSAEK) an air bubble is left inside the anterior chamber to promote graft attachment during the early postoperative period. In the case of insufficient graft adhesion a renewed intracameral air injection is often necessary. The use of sulfur hexafluoride diluted with air (SF6 20 %) as an alternative to pure air may further enhance graft attachment and reduce the rebubbling rate. The effect of SF6 20 % on corneal endothelium is currently unclear and was therefore examined in vitro.

MATERIAL AND METHODS

For this study 12 human corneoscleral discs were mounted in artificial anterior chambers, the systems were continuously filled with culture medium and the anterior chambers with air (n = 5) or SF6 20 % (n = 7) as tamponade. After 6 days of storage in the incubator endothelial cell density, toxicity on endothelial cells and corneal thickness were evaluated.

RESULTS

There were no significant differences in endothelial cell loss (p = 1.000), endothelial cell count (p = 0.648), toxicity on endothelial cells (p = 0.048) and central corneal thickness (p = 0.905) between the two groups after 1 week. The level of significance was defined as p ≤ 0.05 and adjusted to p ≤ 0.0056 according to the Bonferroni correction for multiple testing.

CONCLUSION

The use of SF6 20 % as tamponade in the anterior chamber for posterior lamellar keratoplasty can be proposed as a safe alternative to pure air filling related to endothelial cell loss. Increased toxic effects on the corneal endothelium by SF6 20 % were not detected in this study; however, further prospective clinical trials are needed to examine the long-term effects in humans.

"Salt and Pepper Endothelium" Recurring After Descemet Membrane Endothelial Keratoplasty

PURPOSE

To describe the presence of "salt and pepper endothelium", that is, typical cellular inclusion bodies in a patient with Fuchs endothelial corneal dystrophy (FECD), that recurred in the donor corneal endothelial cells after Descemet membrane endothelial keratoplasty (DMEK).

METHODS

A 76-year-old man underwent DMEK for FECD in his left eye. Routine specular microscopy imaging, best-corrected visual acuity measurements, and pachymetry measurements were performed before and after surgery.

RESULTS

Besides large guttae indicating FECD, preoperative specular microscopy images showed variable-sized dark cellular inclusion bodies in the endothelial cells. One month after DMEK, donor endothelial cells appeared normal; however, at 3 months, the typical inclusion bodies reappeared and progressed slowly within a 4-year follow-up period. Both best-corrected visual acuity and pachymetry were stable throughout the study period.

CONCLUSIONS

"Salt and pepper endothelium" recurred after the host tissue was exchanged by donor Descemet membrane, that is, a DMEK graft. These changes may indicate that either the donor corneal endothelial cell morphology is modified by adjacent tissue structures or that it is completely replaced by recipient endothelium within the first months after surgery.

Causes that influence the detachment rate after Descemet membrane endothelial keratoplasty

PURPOSE

To investigate Descemet graft (DG) detachment rate after Descemet membrane endothelial keratoplasty (DMEK) in relation to DG position.

METHODS

A total of 175 consecutive pseudophakic eyes that underwent DMEK (175 eyes for Fuchs endothelial dystrophy) from September 2009 through February 2014 at the Tübingen Eye Hospital DG position were studied retrospectively by surgical video at the end of an operation. A group of 45 eyes showed a decentration of the DG with a stromal gap of ≥1.5 mm over at least 3 clock hours between the descematorhexis edge and the DG. DG detachment was documented at a mean follow-up of 13.9 ± 3.7 months after surgery. DG detachment was defined as a detachment of 20 % or more of the DG surface area. Various donor characteristics and patient characteristics were analyzed.

RESULTS

The best spectacle-corrected visual acuity (BCVA) in the group of eyes with central well-positioned DG differed significantly from those of eyes with decentered DG. The preoperative BCVA in the central well-positioned DG group was 0.63 ± 0.40 logMAR, and in the decentered DG group 0.91 ± 0.51 logMAR (P < 0.001). The postoperative BCVA in the group of eyes with central well-positioned DG was 0.12 ± 0.11 logMAR, and in the group with decentered DG 0.23 ± 0.29 logMAR (P < 0.001). Endothelial cell density and patient characteristics such as age, gender, and intraocular pressure did not differ significantly between the two groups. The group of eyes with central well-positioned DG showed DG detachment in 12 %; the group with decentered DG findings had DG detachment in 87 % (P < 0.001) at the 12 month follow up.

CONCLUSION

The present findings demonstrate the importance of central well-positioned DG and the relation of disease severity. Central well-positioned DG may reduce the incidence of DG detachment. Overlapping of the donor DG and the host Descemet membrane seems to be responsible for DG detachment. One possible way to enhance graft adhesion could be a larger descematorhexis, which avoids an overlapping. The second possible way could be not waiting too long for surgery to reduce disease severity.

Progress in corneal wound healing

Corneal wound healing is a complex process involving cell death, migration, proliferation, differentiation, and extracellular matrix remodeling. Many similarities are observed in the healing processes of corneal epithelial, stromal and endothelial cells, as well as cell-specific differences. Corneal epithelial healing largely depends on limbal stem cells and remodeling of the basement membrane. During stromal healing, keratocytes get transformed to motile and contractile myofibroblasts largely due to activation of transforming growth factor-β (TGF-β) system. Endothelial cells heal mostly by migration and spreading, with cell proliferation playing a secondary role. In the last decade, many aspects of wound healing process in different parts of the cornea have been elucidated, and some new therapeutic approaches have emerged. The concept of limbal stem cells received rigorous experimental corroboration, with new markers uncovered and new treatment options including gene and microRNA therapy tested in experimental systems. Transplantation of limbal stem cell-enriched cultures for efficient re-epithelialization in stem cell deficiency and corneal injuries has become reality in clinical setting. Mediators and course of events during stromal healing have been detailed, and new treatment regimens including gene (decorin) and stem cell therapy for excessive healing have been designed. This is a very important advance given the popularity of various refractive surgeries entailing stromal wound healing. Successful surgical ways of replacing the diseased endothelium have been clinically tested, and new approaches to accelerate endothelial healing and suppress endothelial-mesenchymal transformation have been proposed including Rho kinase (ROCK) inhibitor eye drops and gene therapy to activate TGF-β inhibitor SMAD7. Promising new technologies with potential for corneal wound healing manipulation including microRNA, induced pluripotent stem cells to generate corneal epithelium, and nanocarriers for corneal drug delivery are discussed. Attention is also paid to problems in wound healing understanding and treatment, such as lack of specific epithelial stem cell markers, reliable identification of stem cells, efficient prevention of haze and stromal scar formation, lack of data on wound regulating microRNAs in keratocytes and endothelial cells, as well as virtual lack of targeted systems for drug and gene delivery to select corneal cells.

Repeat Descemet Membrane Endothelial Keratoplasty: Secondary Grafts with Early Intervention Are Comparable with Fellow-Eye Primary Grafts

PURPOSE

To evaluate the outcomes of secondary Descemet membrane endothelial keratoplasty (DMEK) after failed primary DMEK.

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Fifty-five DMEK recipients 42 to 89 years of age.

METHODS

An initial consecutive series of 1655 DMEK surgeries was reviewed to identify cases of secondary DMEK after failed primary DMEK (n = 55). A paired fellow-eye analysis was performed with a subgroup of 29 patients who underwent secondary DMEK in 1 eye and successful primary DMEK in the fellow eye.

MAIN OUTCOME MEASURES

Corrected distance visual acuity (CDVA), central corneal thickness, and 1-year endothelial cell loss.

RESULTS

The median follow-up after DMEK regraft was 18 months (range, 3-61 months). All 55 regrafts cleared, 8 (15%) had air reinjected to promote attachment, 1 eye (2%) with trabeculectomy and progressive synechiae demonstrated late endothelial failure, and no rejection episodes occurred (0%). In the paired analysis, the median duration of endothelial decompensation before the regraft was 21 days (range, 2-133 days). At 1, 3, 6, or 12 months, CDVA did not differ between the primary and secondary grafts in fellow eyes (mean difference, ≤2 Snellen letters; P > 0.05 at all examinations). At 1 year, the visual acuity was ≥20/20 in 61%, ≥20/25 in 81%, and ≥20/40 in 100% of the secondary grafts in the paired analysis, excluding 1 eye with retinal problems. Vision differed by ≤1 line between fellow eyes in all but the 1 patient with the longest time to regraft (133 days), who demonstrated central haze and irregular astigmatism from anterior stromal scarring during that period. At 1 year, CDVA associated with the scarring was 20/40 versus 20/20 for the fellow-eye primary graft. The central corneal thickness was comparable between fellow-eye primary and secondary grafts at 3, 6, and 12 months (mean difference at 1 year, 2 μm; P = 0.57). The 1-year endothelial cell loss was comparable in primary and secondary grafts (27% vs. 31%, respectively; P = 0.58).

CONCLUSIONS

In patients who received prompt intervention to minimize the duration of central corneal decompensation, the visual outcomes with secondary DMEK matched the fellow-eye visual outcomes with primary DMEK.

Descemet membrane endothelial keratoplasty

Descemet membrane endothelial keratoplasty (DMEK) allows for selective replacement of damaged endothelial cells, using only donor Descemet's membrane with endothelium. However, early adoption by corneal surgeons has been limited (illustrated by graft registry reports: 0.7% all corneal transplants in the USA; 0.4% in Australia for 2011) due to challenges in donor preparation and surgical technique. Recently, innovative donor preparation techniques may improve availability of pre-stripped DMEK donors from eye banks. The refinement of donor insertion and manipulation techniques has also improved outcomes and reduced graft detachment rates-still, the most common postoperative complication following DMEK. Randomised studies are needed to compare clinical practices and surgeon preferences, such as intraoperative use of long-acting gas, early versus late intervention of graft detachments and postoperative steroid management. A review of current literature reveals that most publications to date are reports from similar study cohorts by surgeons who pioneered and advocate this technique. Thus, more long-term clinical studies in other tertiary centres are required in order to confirm if the purported advantages of DMEK such as improved visual outcomes and reduced graft rejection are replicable among most corneal surgeons.

A new clinico-tomographic classification and management algorithm for Descemet's membrane detachment

OBJECTIVE

To propose a new clinico-tomographic classification of Descemet's detachment (DD).

METHODS

Interventional case series of 35 eyes with DD were clinico-tomographically classified as: (1)Rhegmatogenous DD (RDD)-lax, free floating DM secondary to DM tear/hole/dialysis; ASOCT showing undulating linear signal with total length equalling overlying stromal arc length. (2) Tractional DD (TDD)-foreshortened, taut DM with tractional/fibrotic component; ASOCT showing detached DM chord length less than overlying stromal arc length. (3) Bullous DD (BDD)-bulge of DM into AC in absence of DM break or needle puncture break too small to allow egress of contents; ASOCT showing convex signal. (4) Complex DD (CDD)-Complex variants and combinations seen clinically and on ASOCT.

RESULTS

RDD was most common (n=23), 19 were RDD with tear (post-surgical) treated by observation(n=3)/pneumodescemetopexy(n=16), 2 were RDD with hole due to inadvertent DM perforation in deep anterior lamellar keratoplasty treated by pneumodescemetopexy and fibrin glue, 2 were RDD with dialysis post-Descemetorhexis in Descemet's Membrane Endothelial Keratoplasty, not requiring treatment. TDD (n=4) was treated by relaxing Descemetotomy (n=3) or EK (n=1, poor endothelium); BDD (n=3) with two improving spontaneously; CDD (n=5) treated by refloatation with air (n=3)/EK (n=1)/penetrating keratoplasty (n=1).

CONCLUSION

Treatment and prognosis of DD varies based on etio-morphology. This classification allows systematic approach for diagnosis, management and prognostication.

Spontaneous long-term course of persistent peripheral graft detachments after Descemet's membrane endothelial keratoplasty

BACKGROUND

Peripheral corneal graft detachment after Descemet's membrane endothelial keratoplasty (DMEK) is a frequently occurring postoperative complication. The natural course of these persistent peripheral detachments over time is not known.

METHODS

166 patients were surveyed by slit-lamp-adapted optical coherence tomography (SL-OCT) directly after surgery, during first postoperative week, 4 weeks, 3, 6 and 12 months, postoperatively. Patients with a persistent peripheral graft detachment 4 weeks after DMEK (n=16) were observed for their spontaneous course up to 1 year postoperatively.

RESULTS

Persistent graft detachments could be characterised into two phenotypes: peripheral roll (n=11; 69%) and laminar detachment (n=5; 31%). Maximal length of the detachment did not change in peripheral rolls during observation period (12 months vs 4 weeks, 578±122 µm vs 593±106 µm, p=0.74), whereas laminar detachments spontaneously attached to the host's stroma (12 months vs 4 weeks, 0 µm vs 1088±295 µm, p≤0.001). Central corneal thickness and (peripheral) corneal thickness above the detached area did not significantly change in either group.

CONCLUSIONS

Persistent peripheral graft detachments after DMEK occurred in 10% of patients and had two distinct OCT-phenotypes. Peripheral rolls did not change during the first 12 months, postoperatively. By contrast, peripheral laminar detachments attached spontaneously even months after surgery. Corneal thickness reduction was only observed above peripheral laminar detachment, but not above peripheral rolls.