Failed descemet-stripping automated endothelial keratoplasty grafts: a clinicopathologic analysis

Risk Factors for Fibrous Ingrowth in Eyes Requiring Primary Keratoplasty

PURPOSE

The aim of this study was to define risks for corneal transplantation associated with fibrous ingrowth among first-time transplant recipients.

METHODS

We performed a retrospective case-control study of patients with a histopathologic diagnosis of fibrous ingrowth between 2002 and 2019. Patients with fibrous ingrowth from a first corneal specimen were included. Those with incomplete records were excluded. A 1:2 case-control ratio was used. Controls were matched using surgical indication, surgery year, transplantation method, sex, and age.

RESULTS

Seventy-eight eyes (76 patients) were included and matched with 160 control eyes. The incidence of fibrous ingrowth found on a first corneal transplant was 0.6% per year. The most common keratoplasty indications were pseudophakic corneal edema (n = 25, 32%) and aphakic corneal edema (n = 15, 19%). Cases were more likely to have a history of ocular trauma (odds ratio [OR], 2.94; 95% CI, 1.30-6.30; P = 0.007), uveitis (OR, 2.73; 95% CI, 1.12-6.63; P = 0.022), retinal detachment or previous retinal surgery (OR, 2.40; 95% CI, 1.34-4.30; P = 0.003), glaucoma tube-shunt surgery (OR, 2.70; 95% CI, 1.29-5.65; P = 0.007), aphakia (OR, 3.02; 95% CI, 1.61-5.67; P = 0.0004), or iris derangement (OR, 10.52; 95% CI, 5.45-20.30; P <0.0001). A multivariate logistic regression model using iris derangement, history of ocular trauma, history of uveitis, and history of cataract surgery demonstrated 81% sensitivity and 66% specificity in predicting presence of fibrous ingrowth.

CONCLUSIONS

A history of ocular trauma, uveitis, retinal detachment or previous retinal surgery, glaucoma tube-shunt surgery, aphakia, and iris derangement are risks for detecting fibrous ingrowth among first-time keratoplasty recipients. Patients with these conditions should be monitored closely for corneal decompensation.

Gonioscopic angle evaluation and its correlation with graft survival and post-operative ocular hypertension in patients of Descemet's stripping endothelial keratoplasty

Purpose

To evaluate the gonioscopic changes in patients receiving Descemet's stripping endothelial keratoplasty (DSEK) without pre-existing ocular hypertension (OHT) and to report its correlation with post-surgery OHT, graft survival, and visual outcomes.

Methods

Adult patients who underwent DSEK surgery from April 2014 to March 2018 with at least 2 years of follow-up were analyzed in this retrospective study. Demographic details, indication of DSEK, necessary anterior and posterior segment findings, and the post-DSEK OHT details were documented.

Results

A total of 58 patients (23 males and 35 females) with a mean age of 61.44 ± 8.8 years were included in the study. The most common etiology for DSEK surgery was pseudophakic bullous keratopathy in 47 eyes (81.03%). A total of 22.41% (13/58) eyes showed elevated intra-ocular pressure (IOP) following DSEK surgery. The most common cause of IOP elevation was steroid-induced OHT in seven eyes (12.06%). Gonioscopy examination revealed areas of peripheral anterior synechiae (PAS) in 17 (29.3%) eyes. OHT was found in 4/17 (23.5%) eyes having PAS. Three of these cases required trabeculectomy + goniosynechiolysis (GSL), and the fourth case required GSL alone to control IOP. These four cases also required repeat DSEK for failed grafts. The mean pre-operative best corrected visual acuity was 1.62 logMAR (range 1.17-1.77), which gradually improved to 0.79 logMAR (range 0.3-1.77) after 2 years (p < 0.00001).

Conclusion

PAS was found to be an important factor associated with post-DSEK ocular hypertension in our study. OHT in PAS cases required definitive surgical treatments to control IOP. It adversely affected the graft survival and in turn affected visual outcomes also.

Secondary Endothelial Keratoplasty-A Narrative Review of the Outcomes of Secondary Corneal Endothelial Allografts

BACKGROUND

We review the literature on the efficacy and safety outcomes of secondary Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Literature search of English-written publications up to September 27, 2020 in PubMed database, using the terms "endothelial keratoplasty" in combination with keywords "secondary" or "repeat." In addition, we manually searched the references of the primary articles.

RESULTS

Twenty-seven studies (n = 651 eyes) were retained and reviewed, including 10 studies on repeat DSEK, 8 studies on repeat DMEK, 6 studies of DMEK following DSEK, and 3 studies of DSEK after failed DMEK. All studies reported significant improvement in visual acuity after secondary endothelial keratoplasty (EK). Twelve studies compared visual outcomes between primary and secondary EK, reporting conflicting findings. Sixteen studies reported endothelial cell loss rates after secondary EK, and only 1 study reported significantly increased endothelial cell loss rates compared with primary EK. Allograft rejection episodes occurred in 1.8% of eyes (range, 0%-50%). Six studies compared complication rates between primary and secondary EK eyes, and only 1 study found a higher median number of complications. However, 2 studies reported higher regraft failure rates compared with primary EK eyes.

CONCLUSIONS

Secondary EK is surgically feasible and renders significant visual improvement after failed primary EK, although it is not clear whether visual outcomes and allograft survival are comparable with primary EK, raising the question of whether secondary EK eyes are "low risk" as primary EK eyes. Further larger, prospective studies are encouraged to obtain additional quality data on secondary corneal endothelial allotransplantation.

Repeat keratoplasty in failed Descemet stripping automated endothelial keratoplasty

Purpose:

To evaluate the clinical factors associated with repeat Descemet stripping automated endothelial keratoplasty (DSAEK) or penetrating keratoplasty (PKP) in cases of failed DSAEK.

Methods:

Retrospective observational study of cases with failed DSAEK admitted to our center for a repeat keratoplasty over 5 years (January 2013–Decemeber 2017) was undertaken. Demographic and perioperative details of all cases and type of repeat keratoplasty were recorded. Logistic regression analysis was performed to analyze the factors affecting the type of repeat keratoplasty.

Results:

A total of 94 eyes with failed DSAEK were evaluated. Repeat DSAEK was performed in 66% and PKP in 34% of cases. Significantly increased odds for requiring PKP were observed in association with stromal scarring [odds ratio (OR) = 2.9, P = 0.018)], trainee surgeons (OR = 4.05, P = 0.008), intraoperative complications (OR = 4.58, P = 0.003), scleral fixated intraocular lens or anterior chamber intraocular lens in situ (OR = 33.8, P < 0.001), secondary glaucoma (OR = 3.02, P = 0.015), peripheral anterior synechiae (OR = 8.6, P < 0.001), preoperative corneal thickness (OR = 1.01, P < 0001), time to primary surgery (OR = 1.03, P = 0.03), post-DSAEK host thickness (OR = 1.01, P < 0.001), and time interval from graft failure to regraft (OR = 1.18, P < 0.001). All eyes with congenital hereditary endothelial dystrophy, bee-sting-induced corneal decompensation, Axenfeld-Rieger syndrome, and multiple failed grafts underwent secondary PKP. All cases (nine eyes) that required surgical intervention for secondary glaucoma underwent secondary PKP (P < 0.001).

Conclusion:

Repeat DSAEK is feasible in up to two-third of cases of failed DSAEK. A PKP is required in one-third of cases, and various preoperative, intraoperative and postoperative factors are associated with unsuitability for repeat DSAEK.

Descemet Stripping Endothelial Keratoplasty in Pediatric Patients with Congenital Hereditary Endothelial Dystrophy

PURPOSE

To report the long-term outcomes of Descemet stripping endothelial keratoplasty (DSEK) with suture-assisted donor lenticule insertion performed in different age groups for pediatric patients with congenital hereditary endothelial dystrophy (CHED).

DESIGN

Retrospective case series.

METHODS

Pediatric patients with CHED who underwent DSEK from January 2010 to January 2016 were enrolled. Patients were divided into 2 groups according to their ages: the infant group and the child group. Long-term clinical outcomes and complications were compared.

RESULTS

Thirty eyes of 16 patients were included: 19 eyes (10 patients) in the child group and 11 eyes (6 patients) in the infant group. The average duration of follow-up was 4.08 ± 1.90 years (range 2.5-8.5 years). Corneal transparency scores of the 2 groups on postoperative day 7 were not statistically different. The average postoperative best-corrected visual acuity (BCVA) in the infant group (logMAR 0.32 ± 0.11) was better than that in the child group (logMAR 0.54 ± 0.20; (P = .01). Thirty-three percent of cases in the child group and 86% of cases in the infant group had postoperative BCVA achieved or better than logMAR 0.4. Average endothelial cell loss in the child group was 31.21% ± 9.17%. Lenticule detachment occurred in 3 cases in the child group.

CONCLUSIONS

Improved visual outcomes could be achieved in infant patients with CHED after DSEK without significant complications. Suture-assisted donor lenticule insertion techniques, Descemet membrane stripping, and postoperative sedation are advocated technical points.

The Corneal Basement Membranes and Stromal Fibrosis

Purpose

The purpose of this review was to provide detailed insights into the pathophysiology of myofibroblast-mediated fibrosis (scarring or late haze) after corneal injury, surgery, or infection.

Method

Literature review.

Results

The epithelium and epithelial basement membrane (EBM) and/or endothelium and Descemet's basement membrane (BM) are commonly disrupted after corneal injuries, surgeries, and infections. Regeneration of these critical regulatory structures relies on the coordinated production of BM components, including laminins, nidogens, perlecan, and collagen type IV by epithelial, endothelial, and keratocyte cells. Whether a cornea, or an area in the cornea, heals with transparency or fibrosis may be determined by whether there is injury to one or both corneal basement membranes (EBM and/or Descemet's BM) and delayed or defective regeneration or replacement of the BM. These opaque myofibroblasts, and the disordered extracellular matrix these cells produce, persist in the stroma until the EBM and/or Descemet's BM is regenerated or replaced.

Conclusions

Corneal stromal fibrosis (also termed "stromal scarring" or "late haze") occurs as a consequence of BM injury and defective regeneration in both the anterior (EBM) and posterior (Descemet's BM) cornea. The resolution of fibrosis and return of stromal transparency depends on reestablished BM structure and function. It is hypothesized that defective regeneration of the EBM or Descemet's BM allows key profibrotic growth factors, including transforming growth factor beta-1 (TGF-β1) and TGF-β2, to penetrate the stroma at sustained levels necessary to drive the development and maintenance of mature opacity-producing myofibroblasts from myofibroblast precursors cells, and studies suggest that perlecan and collagen type IV are the critical components in EBM and Descemet's BM that bind TGF-β1, TGF-β2, platelet-derived growth factor, and possibly other growth factors, and regulate their bioavailability and function during homeostasis and corneal wound healing.

Epithelial basement membrane injury and regeneration modulates corneal fibrosis after pseudomonas corneal ulcers in rabbits

The purpose of this study was to investigate whether myofibroblast-related fibrosis (scarring) after microbial keratitis was modulated by the epithelial basement membrane (EBM) injury and regeneration. Rabbits were infected with Pseudomonas aeruginosa after epithelial scrape injury and the resultant severe keratitis was treated with topical tobramycin. Corneas were analyzed from one to four months after keratitis with slit lamp photos, immunohistochemistry for alpha-smooth muscle actin (α-SMA) and monocyte lineage marker CD11b, and transmission electron microscopy. At one month after keratitis, corneas had no detectible EBM lamina lucida or lamina densa, and the central stroma was packed with myofibroblasts that in some eyes extended to the posterior corneal surface with damage to Descemet's membrane and the endothelium. At one month, a nest of stromal cells in the midst of the SMA + myofibroblasts in the stroma that were CD11b+ may be fibrocyte precursors to myofibroblasts. At two to four months after keratitis, the EBM fully-regenerated and myofibroblasts disappeared from the anterior 60-90% of the stroma of all corneas, except for one four-month post-keratitis cornea where anterior myofibroblasts were still present in one localized pocket in the cornea. The organization of the stromal extracellular matrix also became less disorganized from two to four months after keratitis but remained abnormal compared to controls at the last time point. Myofibroblasts persisted in the posterior 10%-20% of posterior stroma even at four months after keratitis in the central cornea where Descemet's membrane and the endothelium were damaged. This study suggests that the EBM has a critical role in modulating myofibroblast development and fibrosis after keratitis-similar to the role of EBM in fibrosis after photorefractive keratectomy. Damage to EBM likely allows epithelium-derived transforming growth factor beta (TGFβ) to penetrate the stroma and drive development and persistence of myofibroblasts. Eventual repair of EBM leads to myofibroblast apoptosis when the cells are deprived of requisite TGFβ to maintain viability. The endothelium and Descemet's membrane may serve a similar function modulating TGFβ penetration into the posterior stroma-with the source of TGFβ likely being the aqueous humor.

Splitting of the Recipient's Descemet Membrane in Descemet Membrane Endothelial Keratoplasty-Ultrastructure and Clinical Relevance

PURPOSE

In Descemet membrane endothelial keratoplasty (DMEK), lamellar splitting of the Descemet membrane (DM) may occur during stripping of host DM, leaving residual DM on the recipient's DMEK interface. The purpose of this study was to determine the incidence rate of lamellar splitting of DM during DMEK and to describe the ultrastructure of DM in these eyes.

DESIGN

Retrospective consecutive case series.

METHODS

setting: Institutional, single-center.

PATIENT POPULATION

Total of 664 eyes with Fuchs endothelial corneal dystrophy (FECD) scheduled for primary DMEK.

INTERVENTION

DMEK.

MAIN OUTCOME MEASURES

The incidence rate of lamellar DM splitting in the recipients' eyes; ultrastructural alterations of stripped DM specimens (transmission electron microscopy); preoperative best-corrected visual acuity (BCVA), central corneal thickness (CCT), and prevalence of diabetes mellitus.

RESULTS

Sixty-three of 664 eyes (9.5%) with FECD showed lamellar splitting of DM resulting in the dissociation of 2 separate layers. Transmission electron microscopy revealed accumulations of banded and wide-spaced collagen between the thicker posterior banded layer and the thin anterior banded layer, which is adhesive to the corneal stroma. Lamellar splitting occurred along these abnormal collagen inclusions, demarcating the borderline between both layers of DM.

CONCLUSIONS

Lamellar DM splitting occurs during DM stripping in almost 10% of eyes with FECD. This phenomenon appears to be caused by abnormal collagenous material deposits at the borderline between anterior and posterior layers of DM.

Complications and management in Descemet's stripping endothelial keratoplasty: analysis of consecutive 430 cases

Purpose:

To analyze the complications and their managements in Descemet's stripping endothelial keratoplasty (DSEK) in consecutive 430 cases by single surgeon in a tertiary eye hospital.

Materials and Methods:

430 eyes of 366 patients with endothelial dysfunctions scheduled for DSEK, were analyzed retrospectively. In all cases donor dissection was performed manually, and ‘Taco’ insertion and unfolding technique was used. Intra-operative and postoperative complications with their managements and outcomes were reviewed retrospectively. Periodic endothelial cell density was analyzed for each patient till the last visit. Follow-up period was between 3 to 60 months (mean 18.7 months).

Results:

13 (3.0%) eyes had operative complications during donor dissection and 16 (3.7%) had during recipient procedure. In 7 (1.6%) eyes, donor lenticule was replaced with a new one during the surgery. In early postoperative period, 21 (4.9%) eyes had donor dislocation and 12 (2.8%) eyes had air-induced pupillary block; and they were managed immediately. 2 cases had primary graft failure and in 1 case had postoperative bacterial endophthalmitis requiring evisceration. In late postoperative period, 48 (11.3%) eyes had secondary glaucoma and 14 (3.3%) eyes had late secondary graft failure. Endothelial rejection occurred in 5 (1.2%) cases. Mean endothelial cell loss was 19.7% after 3 months and 54.2% after 5 years. Total graft failure in this series was 31 (7.2%) and in 17 cases re-DSEK was performed successfully.

Conclusions:

Both operative and postoperative complications do occur in DSEK. Most of these complications can be managed by medical or appropriate surgical means. Some of the complications can be avoided and reduced with experience.

Descemet membrane endothelial keratoplasty as treatment for graft failure after descemet stripping automated endothelial keratoplasty

PURPOSE

To investigate the outcome of Descemet membrane endothelial keratoplasty (DMEK) in patients with graft failure after Descemet stripping automated endothelial keratoplasty (DSAEK).

DESIGN

Retrospective cohort study.

METHODS

setting: Institutional.

STUDY POPULATION

Fifteen eyes of 15 patients that underwent DMEK for graft failure with corneal decompensation following DSAEK were analyzed; 15 eyes with primary DMEK for Fuchs corneal dystrophy were included as control group.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), endothelial cell density (ECD), central corneal thickness (CCT), and rebubbling rate.

RESULTS

DMEK surgery was successful in all cases of both groups. Mean BCVA (logMAR) before DMEK was 1.27 ± 0.34 in the DMEK after DSAEK group and 1.0 ± 0.40 in the Primary DMEK group. After DMEK, mean BCVA increased significantly to 0.23 ± 0.21 (P = .012, DMEK after DSAEK group) and 0.29 ± 0.23 (P = .042, Primary DMEK group) after 3 months. There were no significant differences in mean BCVA between both groups at each visit. The rebubbling rate was 13% in the DMEK after DSAEK group and 40% in the Primary DMEK group (P = .1). Mean CCT decreased significantly in both groups 1 month after DMEK (P < .05). Mean ECD and change of ECD did not differ significantly between both groups at each visit (P > .05).

CONCLUSION

The results after DMEK as a procedure to treat graft failure after DSAEK were as good as in patients that underwent DMEK as primary intervention to treat advanced Fuchs dystrophy. This indicates that the optical quality can be reestablished by DMEK in patients with failed DSAEK.

Epithelial Downgrowth after Intraocular Surgery Treated with Intracameral 5-Fluorouracil

Purpose. To present the clinical and histopathologic correlation of two cases of epithelial downgrowth (EDG) after prior intraocular surgery. Methods. Observational case reports. Results. We present two cases of EDG occurring after intraocular surgery. In both cases, after two anterior chamber injections of 5-fluorouracil (5FU), the area of EDG initially regressed. In Case 1, a limited area of EDG eventually recurred, and penetrating keratoplasty with cryotherapy was curative. In Case 2, subsequent corneal edema required Descemet-stripping automated endothelial keratoplasty, and the patient remained clinically free of EDG without further treatment. Conclusion. Intracameral 5FU may have a role in the treatment of EDG after intraocular surgery, though its precise utilization and impact remain to be defined.

Cellular and extracellular matrix modulation of corneal stromal opacity

Stromal transparency is a critical factor contributing to normal function of the visual system. Corneal injury, surgery, disease and infection elicit complex wound healing responses that serve to protect against insults and maintain the integrity of the cornea, and subsequently to restore corneal structure and transparency. However, in some cases these processes result in prolonged loss of corneal transparency and resulting diminished vision. Corneal opacity is mediated by the complex actions of many cytokines, growth factors, and chemokines produced by the epithelial cells, stromal cells, bone marrow-derived cells, lacrimal tissues, and nerves. Myofibroblasts, and the disorganized extracellular matrix produced by these cells, are critical determinants of the level and persistence of stromal opacity after corneal injury. Decreases in corneal crystallins in myofibroblasts and corneal fibroblasts contribute to cellular opacity in the stroma. Regeneration of a fully functional epithelial basement membrane (BM) appears to have a critical role in the maintenance of corneal stromal transparency after mild injuries and recovery of transparency when opacity is generated after severe injuries. The epithelial BM likely has a regulatory function whereby it modulates epithelium-derived growth factors such as transforming growth factor (TGF) β and platelet-derived growth factor (PDGF) that drive the development and persistence of myofibroblasts from precursor cells. The purpose of this article is to review the factors involved in the maintenance of corneal transparency and to highlight the mechanisms involved in the appearance, persistency and regression of corneal opacity after stromal injury.

The clinical characteristics of fungal keratitis in eyes after Descemet's stripping and automated endothelial keratoplasty

The purpose of this study was to describe the clinical characteristics of fungal keratitis caused by Candida albicans in an eye after Descemet stripping automated endothelial keratoplasty (DSAEK). A 72-year-old male with a history of three trabeculectomies, cataract surgery, and two DSAEK procedures developed a corneal ulcer in his right eye two years after his last DSAEK. Fungal keratitis was most likely related to the immunosuppressive conditions that occurred due to the previous operations, the continuous use of steroid eye drops, and the use of disposable soft contact lenses. A smear and culture from the ulcer detected Candida albicans. Slit-lamp examination showed the characteristic feature was the presence of interface infiltrates located between the host and the graft cornea and in the enlarged area around the ulcer. Two weeks after intense antimycotic treatments with voriconazole, miconazole, and natamycin, perforation of the cornea occurred and further therapeutic penetrating keratoplasty was required. Histological analysis revealed an accumulation of infiltrated cells and fibrotic tissue. The poor prognosis for fungal keratitis that occurs in eyes after undergoing DSAEK may be related to the rapid expansion of inflammatory cells through the interface between the host and the graft. In eyes that develop fungal keratitis after DSAEK, special attention should be paid to the possibility that perforation could occur in these patients.

Interface haze associated with topical nonsteroidal anti-inflammatory drug use after descemet stripping automated endothelial keratoplasty

PURPOSE

To determine if topical nonsteroidal anti-inflammatory drug (NSAID) use after Descemet stripping automated endothelial keratoplasty (DSAEK) is associated with the development of interface haze.

METHODS

A retrospective case-control study of patients undergoing DSAEK surgery.

RESULTS

Of the 61 patients receiving topical NSAIDs, 51% were noted to develop interface haze, and 9% of the control group (N=100, no NSAID) developed haze. There was no significant difference in best corrected visual acuity between the 2 groups.

CONCLUSIONS

Topical NSAID use is associated with the development of interface haze, although it may not be visually significant and could be related to confounding factors.

Hybrid Technique of Lamellar Keratoplasty (DMEK-S)

Purpose: To evaluate the outcomes of the hybrid technique of posterior lamellar keratoplasty (DMEK-S). Materials and Methods: 71 eyes of 55 patients enrolled in a single-center study underwent posterior lamellar keratoplasty with a hybrid lamella DMEK-S implanted using a solution implantation technique, owing to endothelial dysfunction. The outcome measures studied were visual acuity and endothelial cell density. Results: The rate of endothelial cell loss caused by surgery was 43.8%. During followups, we observed the stabilization of postoperative findings, or at minimum a very low rate of corneal endothelial cell loss. The UCDVA and BCDVA dramatically improved postoperatively. The rebubbling rate in our group of patients was 61.9%. We replaced the lamella due to its failure or malfunction in 17 patients (23.9%). Conclusion: In summary, DMEK-S combines the advantages of DSEK/DSAEK and DMEK. The central zone of bare Descemet's membrane and endothelium allows for very good visual outcomes, and the peripheral rim allows for better manipulation of the lamella during implantation. It is an effective method of treating the endothelial dysfunction of various etiologies, but the high complication rate needs to be addressed before widespread implementation of the technique in the future.

Visual outcome and histological findings following femtosecond laser-assisted versus microkeratome-assisted DSAEK

BACKGROUND

The aim of this study was to compare the visual outcome of femtosecond laser-assisted Descemet stripping automated endothelial keratoplasty (DSAEK) to microkeratome-assisted DSAEK as well as to contrast precut versus surgeon-cut grafts. Histologic characterization of failed DSAEK grafts was performed in order to correlate ultrastructural changes with graft failures.

METHODS

In this case control study, 47 cases of DSAEK were investigated in terms of visual acuity, keratometric astigmatism, spherical equivalent, endothelial cell count, and postoperative complications. We formed three groups: the femtosecondlaser-assisted DSAEK with precut grafts, the microkeratome-assisted DSAEK with precut and with surgeon-cut grafts. Mean follow-up was 6 months. In the case of graft failure, penetrating keratoplasty was performed, and the excised corneal buttons were investigated by light and electron microscopy.

RESULTS

Microkeratome-assisted DSAEK lead to better visual outcome than femtosecond laser-assisted DSAEK. Keratometric astigmatism, spherical equivalent and endothelial cell count did not differ significantly between both methods. Precut and surgeon-cut grafts in microkeratome-assisted DSAEK did not show any significant difference regarding all upraised parameters. No definite histological correlate for graft failure following femtosecond laser-assisted DSAEK was found.

CONCLUSIONS

Femtosecond laser-assisted DSAEK is not the method of choice, and needs further technical improvement. However, failed femtosecondlaser-assisted DSAEK grafts did not show significant histological changes related to the technique to explain reduced visual acuity. In microkeratome-assisted DSAEK, the preparation time point of the graft does not seem to influence the visual and optical outcome.

Spontaneous reattachment of a posteriorly dislocated endothelial graft: a case report

A thirty-year-old Chinese man with a history of severe trauma to his right eye, with secondary sectoral aniridia and multiple operations including intraocular lens insertion more than fifteen years ago, underwent an uneventful Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) for his pseudophakic bullous keratopathy in a tertiary hospital in Hong Kong. The nature of his previous operations was unknown to the surgeon at the time of transplant. On postoperative day one, the graft was not present in the anterior chamber. Fundal view was limited because of corneal oedema. B-scan ultrasonography could not detect any definite presence of a donor button in the posterior segment as gas was present in the vitreous cavity. The patient was instructed to lie prone full time, and on postoperative day three, the graft was found to be reattached to the stroma with spontaneous resolution of corneal oedema, indicating restoration of pump function of endothelium graft. This is the first case of spontaneous reattachment of a posteriorly dislocated endothelial graft without surgical intervention or abandonment of the grafted endothelial button.

Comparative outcomes of penetrating and component endothelial cell corneal allografts in outbred sheep

Lamellar (component cell) corneal transplantation is replacing penetrating keratoplasty for some corneal disorders in humans, but the relative risks of immunological graft rejection for the two procedures remain uncertain. A model of component endothelial cell keratoplasty (endokeratoplasty) was developed in outbred sheep. Clinical and histological graft outcomes after endokeratoplasty were then compared with contemporaneous penetrating corneal allografts. No topical or systemic immunosuppression was administered to any recipient sheep. Endothelial cell allografts (n = 10) took significantly longer to achieve perfect transparency following surgery than did penetrating corneal grafts (n = 7) (day 10 vs. day 4; p = 0.003; two-tailed Mann-Whitney U test). The median day to rejection of penetrating grafts was postoperative day 18; for endothelial cell grafts, it was day 48 (p = 0.04; two-tailed Mann-Whitney U test). The clinical courses of the two procedures were therefore quite different. Penetrating grafts gained clarity quickly but exhibited rapid graft neovascularization. Clinical rejection was preceded by inflammation in the anterior segment. Endothelial cell grafts exhibited a fluctuating, more indolent course of opacification, although all did eventually fail. Histological analysis confirmed immunological rejection in all failed grafts, but with different patterns of leukocytic infiltration in endokeratoplasties compared with penetrating keratoplasties. Inflammatory cells in endothelial cell grafts were generally fewer in number and were more often found in the posterior stroma. We conclude that, in the absence of immunosuppression, all endothelial cell allografts do undergo immunological rejection, albeit at a slower rate than penetrating grafts.

Research progress on the negative factors of corneal endothelial cells proliferation

The human corneal endothelium forms a boundary layer between anterior chamber and corneal stoma. The corneal endothelial cells are responsible for maintaining cornea transparency, which is very vital for our visual acuity, via its pump and barrier functions. The adult corneal endothelial cells in vivo lack proliferation in response to the cell loss caused by outer damages and diseases. As a result, in order to compensate for cell loss, corneal endothelial cells migrate and enlarge while not via dividing to increase the endothelial cell density. Therefore, it is not capable for corneal endothelium to restore the corneal clarity. Some researches have proved that in vitro the corneal endothelial maintained proliferation ability. This review describes the current research progress regarding the negative factors that inhibit proliferation of the corneal endothelial cells. This review will mainly present several genes and proteins that inhibit the proliferation of the corneal endothelial cells, of course including some other factors like enzymes and position.

Descemet-stripping automated endothelial keratoplasty for vitrectomized cases with traumatic aniridia and aphakic bullous keratopathy

The surgical indication for Descemet-stripping automated endothelial keratoplasty (DSAEK) is largely limited to phakic or pseudophakic cases of endothelial dysfunction with normal pupils, because the endothelial lenticule is generally attached to the recipient cornea by use of gas tamponade into the anterior chamber. Although it may be desirable for vitrectomized cases with aniridia and aphakic bullous keratopathy without capsule support to undergo DSAEK, one of the major problems is lenticule detachment during surgery or in the postoperative period. To perform DSAEK in such cases, special surgical techniques are needed in order to facilitate adhesion of the lenticule. Herein, we describe a suture technique for attaching the endothelial lenticule in DSAEK for aniridic and aphakic cases that have undergone vitrectomy for traumatic vitreoretinal disease.

In vivo evaluation of DSAEK interface with scanning-laser confocal microscopy

BACKGROUND

Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) allows selective replacement of the endothelium. Post-operative haze and particles can affect the interface quality and, ultimately, visual outcome. In this study, we evaluated DSAEK interface with in vivo laser confocal microscopy (LCM) in order to: (i) correlate interface status with best corrected visual acuity, and (ii) with time from surgery; (iii) correlate interface particle number with best corrected visual acuity. Host-donor interface was imaged and graded using a published reflectivity scale. Particles at the interface were counted.

METHODS

18 eyes of 16 patients (6 males and 10 females); mean age: 74 ± 8.3 years which underwent DSAEK were examined by means of in vivo laser confocal microscopy between 1 and 24 months after surgery. Host-donor interface was imaged and graded using a published reflectivity scale. Particles present at the interface were counted.

RESULTS

Interface reflectivity was 2.17 ± 1.2 and significantly correlated with visual acuity (Spearman correlation coefficient -0.83; P < 0.001), and with time after surgery (Spearman correlation coefficient -0.87; P < 0.001). Visual acuity was 0.67 ± 0.27. The number of particles was 205 ± 117.8; no correlation was found between this number and visual acuity (Spearman correlation coefficient -0.41; P = 0.15).

CONCLUSION

DSAEK interface imaged with LCM is helpful in diagnosing poor host-donor interface quality in DSAEK surgery. A good quality interface is related to a better visual acuity. Moreover, the quality of the interface appears to improve as time passes from the surgery. Interface quality is related with visual acuity and improves with time from surgery. LCM should be considered as an added tool in post-DSAEK follow-up of patients. Finally, our study shows that the presence of particles does not influence visual outcome.

Endothelial keratoplasty: a revolution in evolution

Endothelial keratoplasty (EK) is continually evolving both in surgical technique and clinical outcomes. Descemet's stripping endothelial keratoplasty (DSEK) has replaced penetrating keratoplasty (PK) as the treatment of choice for corneal endothelial dysfunction. It is safe and predictable and offers early visual rehabilitation. Newer iterations include Descemet's membrane endothelial keratoplasty, Descemet's membrane automated endothelial keratoplasty, and other hybrid techniques. Early data on these newer EK techniques suggests that they provide significantly better visual outcomes compared to DSEK. Initial 5-year survival data indicates that EK is at least comparable to PK, and more widespread survival data is anticipated. Further work is needed to simultaneously optimize visual outcomes, refractive predictability, and endothelial cell survival, as well as surgical techniques of donor preparation and insertion.

Ophthalmic transplantology: anterior segment of the eye - part I

Background

Transplantology is a quickly developing field of ophthalmology. It currently is able to treat many inherited, degenerative, inflammatory, traumatic, and cancerous diseases. This review outlines recent concepts and methods of treating ocular diseases with tissue and cell grafts. Ocular transplants related to the anterior part of the eye, including the conjunctiva and the cornea, are reviewed in Part 1.

Material/Methods

The scientific literature dated from January 2005 to July 2011 was thoroughly searched using Medline and PubMed. Publications dated 2009, 2010, and 2011 were analyzed in detail. Search terms were as follows: auto-, homo-, heterologous transplantation, eyeball, ocular adnexa, anterior segment of the eye, cornea, lamellar keratoplasty, stem cells, cultured cells. Further data were found at the website of the Eye Bank Association of America.

Results

Nearly all tissues of the anterior segment of the eye (the conjunctiva, sclera, eye muscles, and cornea) are transplanted. Because of the recent significant progress in the field, cornea transplantation was analyzed in more detail, specifically procedures such as limbus grafts and anterior and posterior lamellar keratoplasty. Indications, advantages, and drawbacks of the transplant techniques were also reviewed.

Conclusions

Recent progress in the field of cornea transplants allows treatment at the level of the endothelium and the use of cultured limbal epithelial stem cell grafts. However, compared with previous techniques, modern and multilayered transplant techniques of the cornea require much more expertise and longer training of the surgeon, as well as expensive and technologically advanced equipment. The availability of donor tissue is still the main limitation affecting all transplants. Therefore, cell culturing techniques such as stem cells, as well as artificial cornea projects, seem to be very promising.

Dislocation of the donor graft to the posterior segment in descemet stripping automated endothelial keratoplasty

PURPOSE

To report a series of dislocations of the donor graft into the posterior segment associated with Descemet stripping endothelial keratoplasty (DSAEK) and to identify possible risk factors for dislocation and clinical outcomes.

DESIGN

Retrospective case series.

METHODS

Cases of donor graft dislocation into the posterior segment associated with endothelial keratoplasty were identified from the clinical experience of 7 surgeons. Observations included the preoperative surgical history of each eye, preoperative and postoperative visual acuity, management of the complication, and the postoperative clinical course. No identified cases were excluded from this series.

RESULTS

Eight posterior graft dislocations were associated with DSAEK surgery. Each eye had a history of vitrectomy. Five eyes had sutured posterior chamber intraocular lenses, 1 eye had a sulcus intraocular lens, and 2 eyes were aphakic. Each eye required repeat grafting, and in 6 of 8 eyes, pars plana vitrectomy was used to remove the dislocated graft. Final visual acuities ranged from 20/30 to no light perception.

CONCLUSIONS

Graft dislocation into the posterior segment is a rare complication of DSAEK surgery that can lead to permanent vision loss. It has occurred in eyes that have undergone previous vitrectomy and complicated intraocular lens placement or were aphakic. As is the case with a dropped lens nucleus during cataract extraction, visual acuities after a dropped DSAEK graft range from very good to no light perception. Better postoperative results seem to be associated with prompt removal of the posteriorly dislocated graft.

Donor and surgical risk factors for primary graft failure following Descemet's stripping automated endothelial keratoplasty in Asian eyes

Background

Descemet’s stripping automated endothelial keratoplasty (DSAEK) has been shown to have superior refractive and visual results compared with penetrating keratoplasty, but higher rates of primary graft failure (PGF). This paper presents donor and surgical risk factors for PGF in DSAEK cases in Asian eyes.

Design

Retrospective case-control study.

Participants

All consecutive patients who underwent DSAEK at a tertiary referral teaching hospital from March 2006–December 2008.

Methods

Donor details analyzed were: age of donor, cause of donor death, death to harvesting time, donor storage time, distribution distance of tissue, preoperative endothelial cell count. Surgical factors analyzed were: donor diameter, donor thickness, and method of donor insertion. These risk factors in cases of PGF were compared with patients with successful DSAEK as the control group.

Main outcome measure

PGF.

Results

A total of 124 DSAEK procedures were performed. Six DSAEK procedures (five eyes of five patients; one eye with two failures) resulted in PGF (4.8%). Significant risk factors were found for PGF to include graft insertion using a folding technique (odds ratio [OR], 34.03; 95% confidence interval [CI], 3.75–314.32; P = 0.0017) and a small donor diameter (OR, 39.94; 95% CI, 2.18–732.17; P = 0.013).

Conclusion

The results of this study suggest that in Asian eyes with shallow anterior chambers, surgical trauma relating to the technique of donor insertion, and the use of a small donor are major risk factors for PGF following DSAEK.

Proliferative capacity of corneal endothelial cells

The corneal endothelial monolayer helps maintain corneal transparency through its barrier and ionic "pump" functions. This transparency function can become compromised, resulting in a critical loss in endothelial cell density (ECD), corneal edema, bullous keratopathy, and loss of visual acuity. Although penetrating keratoplasty and various forms of endothelial keratoplasty are capable of restoring corneal clarity, they can also have complications requiring re-grafting or other treatments. With the increasing worldwide shortage of donor corneas to be used for keratoplasty, there is a greater need to find new therapies to restore corneal clarity that is lost due to endothelial dysfunction. As a result, researchers have been exploring alternative approaches that could result in the in vivo induction of transient corneal endothelial cell division or the in vitro expansion of healthy endothelial cells for corneal bioengineering as treatments to increase ECD and restore visual acuity. This review presents current information regarding the ability of human corneal endothelial cells (HCEC) to divide as a basis for the development of new therapies. Information will be presented on the positive and negative regulation of the cell cycle as background for the studies to be discussed. Results of studies exploring the proliferative capacity of HCEC will be presented and specific conditions that affect the ability of HCEC to divide will be discussed. Methods that have been tested to induce transient proliferation of HCEC will also be presented. This review will discuss the effect of donor age and endothelial topography on relative proliferative capacity of HCEC, as well as explore the role of nuclear oxidative DNA damage in decreasing the relative proliferative capacity of HCEC. Finally, potential new research directions will be discussed that could take advantage of and/or improve the proliferative capacity of these physiologically important cells in order to develop new treatments to restore corneal clarity.

Corneal regrafting after endothelial keratoplasty

PURPOSE

To determine the incidence of corneal regrafting after endothelial keratoplasty (EK) and to explore the possible reasons for repeat EK and subsequent penetrating keratoplasty (PK).

METHODS

This retrospective cohort study examined the occurrence of corneal regrafts among 803 eyes of 751 patients who underwent initial EK from January 2004 through February 2009 using donor corneas distributed by a single eye bank. Regression models and life tables evaluated the effects of donor corneal characteristics on the probability of a regraft.

RESULTS

Corneal regrafting after EK occurred in 119 eyes (15%), including 68 with repeat EK and 51 with subsequent PK. Ninety-five regrafts (80%) occurred within 1 year of EK, with 39 (33%) during the first postoperative month. Three years after EK, the cumulative probability of repeat EK was 11% and was 9% for subsequent PK. The secular trend in regrafting indicated an average 4% decline per year from 2005 to 2008. The odds of regrafting occurred less often (P = 0.004) with 202 eye bank-processed corneas than with 601 surgeon-prepared tissues. The cumulative probability of repeat EK was increased if donor corneas were maintained in preservation medium for more than 7 days (P = 0.02). Older donor age, death-to-preservation interval, or lower endothelial density was not significantly associated with repeat keratoplasty.

CONCLUSIONS

Regrafting after EK is becoming less common, possibly because of surgical experience and technical innovations such as eye bank processing of precut tissues. Timely screening and distribution of donor corneas may foster graft survival.

Myofibroblast metaplasia after descemet membrane endothelial keratoplasty

PURPOSE

To describe myofibroblastic metaplasia of corneal endothelial cells in 2 cases with impaired visual function despite complete graft adherence after Descemet membrane endothelial keratoplasty (DMEK).

DESIGN

Interventional case series.

METHODS

In 2 of 90 consecutive DMEK surgeries, the cornea failed to clear up to 6 months postoperatively despite complete graft attachment. After secondary penetrating keratoplasty, both corneal buttons were examined using histopathologic analysis and transmission electron microscopy.

RESULTS

Light microscopy revealed distinct corneal endothelial cell attenuation with the presence of an abnormal posterior collagenous layer in both cases. Most of the remaining endothelial cells had an elongated fibroblast-like appearance with immunopositivity for α-smooth muscle actin indicative of myofibroblast metaplasia. Transmission electron microscopy showed a slightly thickened Descemet membrane with an abnormal posterior fibrillar collagenous layer and a myofibroblast-like transformation of the remaining endothelial cells. Descemet membrane grafts closely adjoined the collagen lamellae of the host corneal stroma similar to the Descemet membrane-stroma interface of a normal cornea.

CONCLUSION

Myofibroblastic metaplasia of attenuated corneal endothelial cells with formation of an abnormal posterior collagenous layer may contribute to an impaired visual function despite complete graft adherence after Descemet membrane endothelial keratoplasty (DMEK).

Clinicopathologic findings in failed descemet stripping automated endothelial keratoplasty

OBJECTIVE

To evaluate the clinical features of and histologic findings from failed Descemet stripping automated endothelial keratoplasty (DSAEK).

METHODS

This retrospective observational case series evaluated 47 consecutive corneal specimens from 42 patients who underwent either penetrating keratoplasty or repeated DSAEK for failed DSAEK. Clinical information was obtained for the cases. Sections of the specimens were examined using light microscopy. Immunohistochemical staining was performed for cytokeratins AE1/AE3 and for the myogenic marker smooth-muscle actin when indicated. Transmission electron microscopic examination was performed in some cases.

RESULTS

Graft survival ranged from 0.5 to 34 months. Histologic examination showed that 94% of the specimens (44 of 47) had endothelial cell loss. Residual host Descemet membrane (19%; 9 of 47), fibrocellular tissue (19%; 9 of 47), epithelial implantation (15%; 7 of 47), and fungal infection (4%; 2 of 47) were also identified. Immunohistochemical stains were positive for AE1/AE3 in the epithelial implantations and for smooth-muscle actin in cells in the fibrocellular proliferations.

CONCLUSIONS

The principal cause of failed DSAEK is endothelial cell loss. Residual host Descemet membrane, fibrocellular tissue at the edge of the lenticule, and epithelial implantation are common histologic findings. Fungal infection may occur in the setting of DSAEK.