Histopathological findings of failed grafts following Descemet's stripping automated endothelial keratoplasty (DSAEK)

Retrocorneal fibrous membrane after phacoemulsification in an eye with pseudoexfoliative glaucoma

OBJECTIVE

To report a case of a retrocorneal fibrous membrane and corneal decompensation following uncomplicated phacoemulsification in an eye with pseudoexfoliative glaucoma.

METHOD

Case report and literature review.

RESULTS

A monocular 83-year-old female developed corneal decompensation 1 year after uncomplicated cataract extraction via phacoemulsification. She had a history of pseudoexfoliative glaucoma and had undergone 3 rounds of selective laser trabeculoplasty in the same eye 3 years prior. Given the resulting corneal edema, the patient underwent Descemet's membrane endothelial keratoplasty, at which time a retrocorneal fibrous membrane was identified. Peeling of the membrane was surgically challenging and resulted in an intraocular hemorrhage intraoperatively and a small iridodialysis because the membrane had extended over the angle and iris. Postoperatively, the cornea cleared well, and vision improved significantly. However, vision was ultimately limited by macular pathology. Pathologic examination demonstrated Descemet's membrane with an attached fibrocellular membrane. Immunostaining for smooth muscle actin was positive within the membrane compatible with a retrocorneal membrane. We also present a review of the literature on modern causes of retrocorneal fibrous membranes.

CONCLUSIONS

Retrocorneal fibrous membranes are encountered most commonly following corneal transplantation and may be surgically challenging to remove. We present the first case of a pathologically proven retrocorneal fibrous membrane following uncomplicated cataract surgery via phacoemulsification and selective laser trabeculoplasty.

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

BACKGROUND/PURPOSE

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

STUDY DESIGN/METHODS

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

RESULTS

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

CONCLUSIONS

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

Local immunosuppression in WZS-pig to rhesus monkey Descemet's stripping automated endothelial keratoplasty: An innovative method to promote the survival of xeno-grafts

Corneal xenotransplantation is an effective solution for the shortage of human corneas. We investigated the feasibility and efficacy of different postoperative protocols on xeno-Descemet's stripping automated endothelial keratoplasty (DSAEK) grafts. Thirty rhesus monkeys were randomly divided into three groups: control group (C), only Descemet's membrane (DM) stripping; DSAEK 1 (D1) and DSAEK 2 (D2) groups, DM stripping followed by endothelial keratoplasty. Betamethasone 3.5 mg was subconjunctival injected in groups control and D1 postoperatively, while animals in group D2 were treated with topical 0.1% tacrolimus and topical steroids. All groups were evaluated by slit-lamp microscopy, anterior segment OCT and LSCM for at least nine months. A total of 24 monkeys (24 eyes) met the inclusion criteria. Nine months after DSAEK surgery, all xenografts showed good attachment, and most corneas were transparent. Graft rejection occurred in 25% of the cases in group D1 and 28.57% of those in group D2 (P > 0.05). The corneal endothelium density in the DSAEK groups was 2715.83±516.20/mm² (D1) and 2220.00 ± 565.13/mm² (D2) (P > 0.05). Xenogeneic corneal endothelial grafts can survive and function in rhesus monkey eyes for a long time with subconjunctival steroid or topical tacrolimus and steroid treatment.

Indications, surgical procedures and outcomes of keratoplasty at a Tertiary University-based hospital: a review of 10 years' experience

OBJECTIVE

To investigate keratoplasty outcomes in a university-based hospital.

METHODS

Medical records of all patients undergoing keratoplasty at King Abdulaziz University Hospital, Riyadh, Saudi Arabia, between January 1, 2006, and December 31, 2015, with a minimum follow-up period of three months were reviewed retrospectively. Indications, surgical procedures, complications and outcomes of all surgeries were collected and analyzed.

MAIN OUTCOME MEASURES

Graft survival and visual acuity.

RESULTS

Data were available for 488 grafts in the study period, including 313 optical penetrating keratoplasty (PKP), 42 therapeutic/tectonic PKPs, 72 deep anterior lamellar keratoplasty, 58 Descemet's stripping automated endothelial keratoplasty and 3 Descemet's membrane endothelial keratoplasty. A total of 389 (79.7%) grafts survived, whereas 99 (20.3%) grafts failed. The projected 1-year, 3-year and 5-year cumulative survival rates for the entire study group were 85.8%, 74.9% and 71.1%, respectively. Corneal ectasia was the commonest surgical indication accounting for 48% of the cases. The best long-term survival rates were observed in the stromal dystrophy and corneal ectasia groups. The worst survival rates were noticed in the congenital corneal opacities group. Vision improved in in 57.5% of grafted eyes, remained the same in 39.8% and deteriorated in 2.7%. Postoperative complications occurred in 36% of the grafts with rejection being the most common, and its mere occurrence increased the risk of graft failure by 20-fold.

CONCLUSION

The outcome of grafting in a university-based hospital can be excellent in low-risk grafts and fair to low in high-risk grafts. Our results are relatively comparable to nationally and internationally reported outcomes.

Clinicopathologic Correlations of Retrocorneal Membranes Associated With Endothelial Corneal Graft Failure

PURPOSE

To provide clinicopathologic correlations for retrocorneal membranes associated with Descemet stripping automated endothelial keratoplasty (DSAEK) failure.

DESIGN

Retrospective case series.

METHODS

The specimens and medical records of the patients diagnosed with clinically significant retrocorneal membranes associated with DSAEK failure at the Bascom Palmer Eye Institute or the University of Miami Veterans Hospital between October 2015 and March 2020 were reviewed for demographics, clinical presentation, comorbidities, and surgeries performed. Histopathologic analysis was performed on hematoxylin-eosin and periodic acid-Schiff sections. Immunohistochemical studies were performed for smooth muscle actin (α-SMA), pancytokeratin, and CK7. Immunofluorescence was performed for vimentin, N-cadherin, ROCK1, RhoA, ZEB1, and Snail.

RESULTS

A total of 7 patients (3 male and 4 female) were identified to have a clinically significant retrocorneal membranes at the time of graft failure. The average age at the time of first DSAEK was 70 years (range: 55-85 years). All patients were pseudophakic and had a glaucoma drainage device in place; 1 had a history of failed DSAEK. Ranging from 0 to 47 months after surgery, a variably thick retrocorneal fibrous membrane was observed, eventually leading to graft failure. Four patients underwent subsequent penetrating keratoplasty and 3 underwent repeat DSAEK. On histopathologic evaluation, a pigmented fibrocellular tissue was identified along the posterior margin of the corneas and DSAEK buttons in all cases. Further characterization with immunohistochemistry and immunofluorescence demonstrated membranes to be negative for pancytokeratin and positive for α-SMA, vimentin, CK7, N-cadherin, ZEB1, Snail, ROCK1, and RhoA.

CONCLUSIONS

Fibrocellular retrocorneal membrane proliferation may be associated with DSAEK failure in patients with previous glaucoma drainage device surgery. Our results demonstrate myofibroblastic differentiation and a lack of epithelial differentiation. Positivity for markers of an endothelial-to-mesenchymal transition indicates possible endothelial origin and could be the hallmark for future targeted pharmacotherapy.

Eye Bank Management of Irregular Descemet Stripping Automated Endothelial Keratoplasty Lenticules

PURPOSE

To report the management of precut Descemet stripping automated endothelial keratoplasty (DSAEK) lenticules unsuitable for transplantation because of irregular anterior profile after microkeratome cutting.

METHODS

After preparation for DSAEK, 20 tissues were considered unsuitable for transplantation because of nonhomogeneous posterior stromal thickness. To convert them into suitable tissues for surgery, manual stromal delamination was performed by removing the excess stromal layers after the indications obtained through optical coherence tomography. These tissues were further transplanted as ultrathin DSAEK.

RESULTS

Nineteen tissues were delaminated successfully. The average reduction in thickness in the center (63 ± 69 μm; P = 0.0101) and periphery (129 ± 39 μm; P < 0.0001) before and after delamination was significantly different. One tissue showed signs of perforation during manual dissection and therefore considered unsuitable for transplantation. Primary graft failure was reported in one case, but it was not correlated with the tissue preparation. No other clinical complications were observed after surgery.

CONCLUSIONS

Manual delamination of the stroma because of irregular microkeratome cutting is a viable option to obtain a uniform graft thickness required for DSAEK surgeries. This technique can further reduce tissue wastage that is observed after microkeratome cutting errors.

Excisional penetrating keratoplasty for fungal interface keratitis after endothelial keratoplasty: surgical timing and visual outcome

PURPOSE

In this paper, we describe two cases of fungal interface infectious keratitis (IIK) developed after endothelial keratoplasty (EK) who underwent delayed therapeutic penetrating keratoplasty (TPK) with a poor visual outcome. Furthermore, we conducted a review of the literature and analyzed the visual outcomes of TPK in relation to the time from IIK diagnosis.

METHODS

We searched the literature for fungal IIK cases occurred after EK and treated by TPK. We identified 17 cases of fungal IIK, mostly caused by Candida spp. (88%).

RESULTS

Infection was diagnosed at a median time of 21 (range 1-90 days) days after EK. The median lag time between infection diagnosis and TPK was 30 (range 7-393) days. The median distance corrected visual acuity (DCVA) measured 4-12 months after surgery was 20/40 (range 20/200-20/20). When TPK was performed within one month from diagnosis, the final median DCVA was 20/30 (range 20/100-20/20), with 83% of patients achieving ≥ 20/40 vision. When TPK was carried out later, the final median DCVA was 20/50 (range 20/200-20/22) with 44% of patients achieving ≥ 20/40 vision. One patient in the early surgery and four patients in the late surgery group showed postoperative DCVA ≤ 20/100 despite clear grafts.

CONCLUSION

TPK with removal of the sequestered infection is advocated as a safe and effective measure to treat a post-EK infection. Early surgery allows a reduced exposure time to infection and therefore may result in better visual outcomes and lower risk of complications caused by prolonged inflammation.

Graft Detachment After Descemet's Stripping Automated Endothelial Keratoplasty in Bullous Keratopathy and Fuchs Dystrophy

Descemet's stripping automated endothelial keratoplasty (DSAEK) is a surgical technique for corneal transplantation in case of corneal decompensation. One of the main complications is graft detachment (GD) recoverable with Air Re-bubbling (ARB). The aim of this retrospective, interventional case series was to identify factors related to this complication in eyes operated for bullous keratopathy (BK) and Fuchs dystrophy (FD). We considered one-hundred patients who underwent DSAEK for BK or FD between January 2016 and October 2017 at Department of Ophthalmology, Policlinico Universitario of Bari, Italy. Studied parameters included physiological and pathological anamnesis of both donors and recipients and properties of donor's lenticules and of the recipient's corneas. Data was analyzed using One-way ANOVA with Tukey post hoc test and Chi-square test with Odds Ratio (OR) calculation. We grouped patients according to diagnosis. GD occurred in 9 eyes affected by BK and 19 by FD (p=0.003, OR = 0.25, 95% CI, 0.098-0.62). It was recovered with ARB. In BK, ARB correlated to complicated cataract extraction (p=0.04, OR = 7.83, 95% CI, 1.28 - 47.98) and aphakia (p=0.026, OR = 54.38, 95% CI, 2.51 - 11.76). In FD, ARB was associated to donor's death for neoplasia (p=0.06, OR= 4.04, 95% CI, 1.06 - 15.37). No other differences were found. In conclusion, we could hypothesize that in FD patients, donor's cancer therapy may play a role on altered corneal fibroblast metabolism, activating a synergetic effect between chemotherapy and genetic alteration of FD, which may lead to an altered adhesion of donor's lenticule on recipient's stroma. In BK patients, complicated cataract extraction and aphakic status of recipients' eye may contribute to altered adhesion of donor's lenticule post-DSAEK.

Development of retrocorneal membrane following pig-to-monkey penetrating keratoplasty

Recent reports of long-term survival after wild-type (WT) pig-to-monkey corneal xenotransplantation are encouraging. We experienced the rapid development of retrocorneal membranes, a rare complication after corneal allotransplantation (although seen in infants and young children). The original specific aim of the study was to determine the factors associated with successful (young) pig corneal transplantation in monkeys. However, when it was obvious that retrocorneal membranes rapidly developed, our aims became to determine the factors involved in its development after both WT and Genetically engineered (GE ) pig corneal xenotransplantation and to investigate the characteristics of the retrocorneal membrane. Rhesus monkeys were recipients of penetrating keratoplasty using WT and GE pigs (n=2, respectively, 1-3 months old). Local/systemic steroids were administered for 3 months. Grafts were evaluated by slit lamp for corneal transparency, edema, and neovascularization. Hematoxylin and eosin, Masson trichrome staining, and immunohistochemical analysis were performed. Gal staining was also carried out to distinguish the origin of the membrane. All penetrating keratoplasty recipients developed fibrous retrocorneal membranes in the early post-transplantation period, regardless of whether the graft was from a WT or GE pig. There were no features of rejection, with no cell infiltrate in the graft or anterior chamber during the three-month follow-up. There was no difference in the clinical course between the two groups (WT or GE corneas). Immunohistochemistry indicated that the retrocorneal membranes were CK negative, α-SMA positive, and vimentin positive, suggesting that they were of fibrous (keratocytic) origin. Also, the membrane was Gal positive, suggesting that it is derived from pig cornea. Following pig-to-monkey corneal xenotransplantation, we report that retrocorneal membranes are derived from donor pig keratocytes. Prevention of retrocorneal membranes will be necessary to achieve successful corneal xenotransplantation.

Candida Interface Infections After Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

To describe 2 Candida interface keratitis infections occurring in the setting of positive donor rim cultures from precut corneal tissue used for Descemet stripping automated endothelial keratoplasty (DSAEK) and the ensuing public health investigation.

METHODS

Following 2 clinical Candida interface keratitis infections, patients from 2012 to 2014 in the same surgical center were evaluated for bacterial and fungal rim cultures and subsequent infection. All cases of fungal infections occurring post-DSAEK were analyzed. Data included patient demographics, surgical technique, donor rim cultures, donor mate outcomes, clinical courses, and outcomes. A review of the relevant literature was also undertaken.

RESULTS

From 2012 to 2014, among 99 DSAEK procedures performed, 7 (7.1%) donor rim cultures were positive for fungi. Use of this tissue with positive donor rim cultures resulted in 2 (28.6%) episodes of confirmed fungal interface keratitis, both Candida species, and presumptive treatment in an additional 2 patients. An investigation did not identify any breach in sterile technique or procedures by the surgeon or surgery center. Our literature review identified 15 reports of postoperative fungal infection associated with DSAEK, of which 11 involved Candida spp.

CONCLUSIONS

While postoperative infection remains rare, our 2 additional cases along with those previously reported suggest that DSAEK may be susceptible to infection with Candida spp. Furthermore, this report of correlated rim cultures and clinical infection suggests a need for reevaluation of the utility of obtaining routine corneoscleral donor rim fungal culture.

Finite Element Analysis of Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) Surgery Allograft to Predict Endothelial Cell Loss

PURPOSE

To develop high fidelity finite element (FE) models of the Descemet's stripping automated endothelial keratoplasty (DSAEK) allograft to estimate the stress distributions generated on the allograft during its deformed state in popular allograft insertion configurations and qualitatively correlate the stress distributions to postsurgical endothelial cell (EC) loss.

MATERIALS AND METHODS

Corneal allograft simulation was performed using ANSYS (Canonsburg, PA, USA) utilizing isotropic nonlinear hyperelastic corneal material properties to evaluate the stress distributions generated on the DSAEK allograft during popular allograft insertion configurations, namely forceps, taco, and double-coil insertion configurations. The gathered FE simulation results were qualitatively compared with published clinical studies to verify the simulation results.

RESULTS

The FE simulation results demonstrate that high stress regions predicted by FE model results correctly predict the areas of postsurgical EC loss as published in the studies available in open literature. The FE simulation stress magnitude results suggest that highest EC loss due to mechanical bending trauma occurs in double-coil configuration followed by forceps and then taco configuration.

CONCLUSIONS

The results of the presented FE simulation study highlight that allograft regions with high stress distribution demonstrate postsurgical EC loss in clinical studies. The modeling procedures presented in this research can be utilized to develop novel surgical devices/techniques that can modulate the postsurgical EC loss due to mechanical bending trauma and facilitate allograft unfolding inside the AC, thereby improving the results of the DSAEK surgical procedure.

Descemet's Stripping Automated Endothelial Keratoplasty Tissue Insertion Devices

This review study provides information regarding the construction, design, and use of six commercially available endothelial allograft insertion devices applied for Descemet's stripping automated endothelial keratoplasty (DSAEK). We also highlight issues being faced in DSAEK and discuss the methods through which medical devices such as corneal inserters may alleviate these issues. Inserter selection is of high importance in the DSAEK procedure since overcoming the learning curve associated with the use of an insertion device is a time and energy consuming process. In the present review, allograft insertion devices were compared in terms of design, construction material, insertion technique, dimensions, incision requirements and endothelial cell loss to show their relative merits and capabilities based on available data in the literature. Moreover, the advantages/disadvantages of various insertion devices used for allograft insertion in DSAEK are reviewed and compared. The information presented in this review can be utilized for better selection of an insertion device for DSAEK.

Clinicopathologic correlation of textural interface opacities in descemet stripping automated endothelial keratoplasty: a case study

PURPOSE

The aim of this study was to describe the clinicopathologic correlation of textural interface opacities (TIOs) in a Descemet stripping automated endothelial keratoplasty (DSAEK) donor button after its removal.

METHODS

A 75-year-old woman underwent combined phacoemulsification with intraocular lens placement and DSAEK in her right eye. She had TIOs 1 week postoperatively and continued to have poor visual acuity 8 months postoperatively. The original DSAEK graft was removed, and a repeat DSAEK procedure with a new donor disc was performed. A control corneal button was obtained from a 79-year-old woman who suffered chronic rejection and had a failed DSAEK. Both corneal specimens were sent for light and electron microscopy.

RESULTS

Light microscopy of the donor tissue from the patient with TIOs showed stromal irregularities projecting from the cut anterior surface and the expected decrease in the endothelial cell density associated with the procedure and with artifacts. Electron microscopy examination showed irregular collagen fibrils of varying lengths at the stromal surface. Light and electron microscopy examination of the donor tissue from the control patient showed a smooth anterior stromal surface without projecting collagen fibrils.

CONCLUSIONS

The histopathology of the endothelial disc from the patient with TIOs demonstrated variably irregular lamellae that extended from the anterior donor corneal stromal surface. These extending lamellae were absent on the anterior stromal surface of the control corneal disc, suggesting that they are one possible cause of TIOs and the subsequent suboptimal best-corrected visual acuity and quality of vision experienced by a subset of DSAEK-operated patients.