Outcome of Descemet membrane endothelial keratoplasty for graft failure after Descemet stripping automated endothelial keratoplasty.

PURPOSE: To investigate the efficacy and safety of Descemet membrane endothelial keratoplasty (DMEK) for corneal decompensation following primary Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: This was a retrospective case series of 15 patients that underwent DMEK surgery for corneal decompensation after failed DSAEK. Main outcome parameter was corrected distance visual acuity (CDVA) after DMEK and DSAEK. Secondary outcome measures included central corneal thickness (CCT), endothelial cell density (ECD), rebubbling rate, and primary graft failure after DMEK. Explanted DSAEK grafts were evaluated by light microscopy. RESULTS: The mean (±SD) time period between DSAEK and DMEK surgery was 15±8 months (range, 6-31 months). Preoperative CDVA was 1.72±0.62 (logMAR). After DMEK, CDVA improved significantly to 0.78±0.48 at 1 month and to 0.23±0.24 after 12 months (P=0.022). Visual acuity data after DMEK were significantly better compared to preoperative values. The average CCT after DMEK decreased significantly from 869±210 µm (preoperative) to 505±45 µm (1 month postoperative) (P<0.001) and remained stable over 12 months. The ECD decreased from 2,589±209/mm2 (preoperative) to 1,691±589/mm2 (12 months postoperative). Rebubbling DMEK was required in three patients (=20%). CONCLUSION: DMEK represents a feasible and safe procedure in achieving better functional results compared to DSAEK. Visual acuity and optical quality can be effectively reestablished after unsuccessful primary DSAEK surgery even in patients with long-standing corneal decompensation. Further investigations are required to validate the preliminary clinical findings.

Functional outcome of repeat Descemet membrane endothelial keratoplasty (DMEK) for corneal decompensation following graft failure after primary DMEK.

PURPOSE: To evaluate if repeat Descemet membrane endothelial keratoplasty (DMEK) is appropriate to achieve functional improvements in patients with corneal decompensation from secondary graft failure after primary DMEK. METHODS: This is a retrospective monocentric cohort study including 13 eyes of 13 patients with repeat DMEK for corneal decompensation following primary DMEK. Eyes with primary DMEK only and comparable preoperative corrected distance visual acuity (CDVA) served as control. Main outcome parameter was CDVA. Secondary outcome measures were central corneal thickness (CCT), endothelial cell density, and rebubbling rate (RR). RESULTS: The average time interval (±SD) between primary and secondary DMEK was 12.5±6 months. Preoperative CDVA (logMAR) was 1.97±0.90 in the repeat DMEK group and 1.38±0.92 in the primary DMEK group. At 6 months, both groups showed significant improvement in visual acuity (repeat DMEK group, 0.49±0.35, P<0.01 and primary DMEK group, 0.40±0.36, P<0.01). CDVA did not differ significantly between both groups at all time points examined (1, 3, and 6 months postoperatively). Mean CCT values at 3 and 6 months postoperatively did not differ significantly between the two groups (P>0.05). The RR was 23% (n=3) in both groups. CONCLUSION: Repeat DMEK is a useful therapeutic approach in the setting of corneal decompensation following primary DMEK. Functional results of repeat DMEK, visual acuity in particular, are comparable to patients with single DMEK only.

Visual results after implantation of a trifocal intraocular lens in high myopes.

PURPOSE: To report visual and refractive outcomes after implantation of a trifocal intraocular lens (IOL) in highly myopic patients. SETTING: Department of Ophthalmology, Goethe University, Frankfurt, Germany. DESIGN: Retrospective case series. METHODS: This study included eyes with previous phacoemulsification and implantation of a trifocal IOL (AT LISA tri 839MP or 939MP) with an IOL power between 0.0 diopter (D) and 10.0 D. Postoperative outcomes at 3 months including uncorrected distance (UDVA), intermediate (UIVA), and near visual acuity (UNVA), corrected distance visual acuity, spherical equivalent, and refractive astigmatism were analyzed. Age-matched eyes after implantation of the same trifocal IOL with higher dioptric power (>10.0 D) served as controls. RESULTS: Thirty-six eyes of 19 patients were included: 18 eyes (10 patients) in the highly myopic group (IOL power 0.0 to 10.0 D) and 18 eyes (9 patients) in the age-matched control group (IOL power >10.0 D). Three months postoperatively, the mean UDVA, UIVA, and UNVA in the highly myopic group were 0.06 logarithm of the minimum angle of resolution (logMAR) ± 0.08 (SD), 0.13 ± 0.09 logMAR, and 0.12 ± 0.07 logMAR, and -0.01 ± 0.10 logMAR, 0.04 ± 0.10 logMAR, and 0.04 ± 0.11 logMAR in the control group, respectively (P = .022, P = .033, P = .053, respectively). CONCLUSION: Implantation of a trifocal IOL in highly myopic eyes with low IOL power (0.0 to 10.0 D) provided satisfactory short-term visual and refractive outcomes; however, results were not as good as those obtained in eyes with higher dioptric IOL power.

Meta-Analysis of Postoperative Outcome Parameters Comparing Descemet Membrane Endothelial Keratoplasty Versus Descemet Stripping Automated Endothelial Keratoplasty.

PURPOSE: This meta-analysis compares Descemet membrane endothelial keratoplasty (DMEK) with Descemet stripping automated endothelial keratoplasty (DSAEK) to evaluate their strength and weakness profiles. DESIGN: Meta-analysis. METHODS: We performed a meta-analysis and searched the peer-reviewed literature in PubMed, Cochrane Library, Web of Science, and Embase following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Prospective and retrospective trials performing and comparing DMEK and DSAEK were included. Effects were calculated as odds ratios or standardized mean differences. RESULTS: A total of 11 studies with a total of 723 eyes (350 DMEK and 373 DSAEK) were included. No significant difference was found regarding the total detachment rate, graft failure, and rejection. One of 340 eyes undergoing DMEK showed total detachment and 5 of 363 eyes undergoing DSAEK showed total detachment (P = 0.28). Six of 280 eyes undergoing DMEK showed graft failure; 1 of 313 eyes undergoing DSAEK developed this complication (P = 0.18). No rejection was observed in 158 eyes undergoing DMEK; 4 cases of rejection occurred in 196 eyes undergoing DSAEK (P = 0.37). No significant difference was found regarding endothelial cell loss (P = 0.48). There was a significantly higher partial detachment rate with DMEK: 88 of 340 eyes undergoing DMEK showed partial detachment; 16 of 363 eyes undergoing DSAEK showed this complication (P < 0.00001). DMEK was superior in best-corrected visual acuity after 6 months (P < 0.001), subjective evaluation of visual acuity (P = 0.001), patient satisfaction (P < 0.001), and was the method preferred by patients (P = 0.001). CONCLUSIONS: DMEK and DSAEK have a similar complication profile. However, the superiority in the visual outcome and patient satisfaction makes DMEK the preferred option for most patients.

Amnion-assisted conjunctival epithelial redirection in limbal stem cell grafting.

AIMS: To develop a technique using amniotic membrane (AM) to prevent admixture of conjunctival epithelial cells and limbal explant-derived corneal epithelial cells in patients undergoing limbal stem cell transplantation. To compare this technique with the current method of 'sequential sector conjunctival epitheliectomy' (SSCE). METHODS: 26 patients with total limbal stem cell deficiency who underwent ocular surface reconstruction with limbal stem cells transplantation were retrospectively studied. Patients were categorised into group A (11) in which AM was used to direct the conjunctival epithelial cells away from the corneal surface so that the latter could be covered by the limbal explant-derived epithelial cells-the procedure was termed 'amnion-assisted conjunctival epithelial redirection' (ACER)-and group B (15) in which the conjunctival epithelium was prevented from migrating on to the corneal surface by SSCE. RESULTS: In nine eyes of group A, the conjunctival epithelium was successfully directed on to the AM, preventing admixture with limbal explant-derived corneal epithelial cells. The AM was removed or it came off spontaneously within 1-4 weeks. Patients treated with SSCE (group B) underwent two to four interventions until complete re-epithelialisation. 12 patients had pain or discomfort. 11 patients had conjunctival haemorrhage during SSCE. The cornea was epithelised from the limbal explant-derived epithelium in all patients. CONCLUSIONS: ACER is a viable option in limbal transplantation that reduces multiple patient visits, bleeding and pain that can be associated with SSCE.

Bilateral rupture of the posterior capsule and intraocular lens dislocation from excessive eye rubbing.

UNLABELLED: We report an unusual case of a 36-year-old woman with severe atopic eczema who developed sudden-onset reduction of vision in the right eye following excessive eye rubbing 9 years after cataract surgery. Examination identified posterior capsule rupture with dislocation of the intraocular lens (IOL) posteriorly into the vitreous cavity in the right eye and posterior capsule rupture with mild dislocation of the IOL in the bag in the left eye. To our knowledge, this is the first reported case of simultaneous bilateral posterior capsule rupture following uneventful surgery and secondary to eye rubbing. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Suppression of alkali-induced oxidative injury in the cornea by mesenchymal stem cells growing on nanofiber scaffolds and transferred onto the damaged corneal surface.

The purpose of this study was to investigate whether rabbit bone marrow-derived mesenchymal stem cells (MSCs) effectively decrease alkali-induced oxidative stress in the rabbit cornea. The alkali (0.15 N NaOH) was applied on the corneas of the right eyes and then rinsed with tap water. In the first group of rabbits the injured corneas remained untreated. In the second group MSCs were applied on the injured corneal surface immediately after the injury and eyelids sutured for two days. Then the sutures were removed. In the third group nanofiber scaffolds seeded with MSCs (and in the fourth group nanofibers alone) were transferred onto the corneas immediately after the injury and the eyelids sutured. Two days later the eyelid sutures were removed together with the nanofiber scaffolds. The rabbits were sacrificed on days four, ten or fifteen after the injury, and the corneas were examined immunohistochemically, morphologically, for the central corneal thickness (taken as an index of corneal hydration) using an ultrasonic pachymeter and by real-time PCR. Results show that in untreated injured corneas the expression of malondialdehyde (MDA) and nitrotyrosine (NT) (important markers of lipid peroxidation and oxidative stress) appeared in the epithelium. The antioxidant aldehyde dehydrogenase 3A1 (ALDH3A1) decreased in the corneal epithelium, particularly in superficial parts, where apoptotic cell death (detected by active caspase-3) was high. (In control corneal epithelium MDA and NT are absent and ALDH3A1 highly present in all layers of the epithelium. Cell apoptosis are sporadic). In injured untreated cornea further corneal disturbances developed: The expressions of matrix metalloproteinase 9 (MMP9) and proinflammatory cytokines, were high. At the end of experiment (on day 15) the injured untreated corneas were vascularized and numerous inflammatory cells were present in the corneal stroma. Vascular endothelial growth factor (VEGF) expression and number of macrophages were high. The results obtained in injured corneas covered with nanofiber scaffolds alone (without MSCs) or in injured corneas treated with MSCs only (transferred without scaffolds) did not significantly differ from the results found in untreated injured corneas. In contrast, in the injured corneas treated with MSCs on nanofiber scaffolds, ALDH3A1 expression remained high in the epithelium (as in the control cornea) and positive expression of the other immunohistochemical markers employed was very low (MMP9) or absent (NT, MDA, proinflammatory cytokines), also similarly as in the control cornea. Corneal neovascularization and the infiltration of the corneal stroma with inflammatory cells were significantly suppressed in the injured corneas treated with MSCs compared to the untreated injured ones. The increased central corneal thickness together with corneal opalescency appearing after alkali injury returned to normal levels over the course of ten days only in the injured corneas treated with MSCs on nanofiber scaffolds. The expression of genes for the proinflammatory cytokines corresponded with their immunohistochemical expression. In conclusion, MSCs on nanofiber scaffolds protected the formation of toxic peroxynitrite (detected by NT residues), lowered apoptotic cell death and decreased matrix metalloproteinase and pro-inflammatory cytokine production. This resulted in reduced corneal inflammation as well as neovascularization and significantly accelerated corneal healing.

Graft survival and cytokine production profile after limbal transplantation in the experimental mouse model.

Limbal transplantation or limbal stem cell (LSC) transfer represents the only way to treat severe ocular surface damage or LSC deficiency. However, limbal allografts are promptly rejected in spite of extensive immunosuppressive therapy. To characterize immune response after limbal transplantation, we established an experimental model of limbal transplantation in the mouse. Syngeneic, allogeneic and xenogeneic (rat) limbal grafts were grafted orthotopically in BALB/c mice and graft survival was evaluated. The presence of graft donor cells and the expression of IL-2, IL-4, IL-10, IFN-γ and inducible nitric oxide synthase (iNOS) mRNA in the grafts were detected by real-time PCR. While syngeneic grafts survived permanently, allografts were rejected in 9.0±1.8 days and xenografts in 6.5±1.1 days. The manifestation of clinical symptoms of rejection correlated with the disappearance of donor cells in the graft and in the recipient cornea. Intragraft expression of iNOS mRNA and distinct expression patterns of Th1 (IL-2, IFN-γ) and Th2 (IL-4, IL-10) cytokines were detected during rejection of limbal allografts and xenografts. The limbal graft rejection was prevented with anti-CD4, but not anti-CD8 monoclonal antibody therapy. The results indicate that limbal grafts do not enjoy immune privilege of the eye and are promptly rejected by Th1 (allografts) or by a combined Th1 and Th2 (xenografts) type of immune response involving CD4+ cells and iNOS expression. Targeting this pathway may be an effective way to prevent and treat limbal graft rejection.

Treatment of ocular surface injuries by limbal and mesenchymal stem cells growing on nanofiber scaffolds.

Stem cell (SC) therapy represents a promising approach to treat a wide variety of injuries, inherited diseases, or acquired SC deficiencies. One of the major problems associated with SC therapy remains the absence of a suitable matrix for SC growth and transfer. We describe here the growth and metabolic characteristics of mouse limbal stem cells (LSCs) and mesenchymal stem cells (MSCs) growing on 3D nanofiber scaffolds fabricated from polyamide 6/12 (PA6/12). The nanofibers were prepared by the original needleless electrospun Nanospider technology, which enables to create nanofibers of defined diameter, porosity, and a basis weight. Copolymer PA6/12 was selected on the basis of the stability of its nanofibers in aqueous solutions, its biocompatibility, and its superior properties as a matrix for the growth of LSCs, MSCs, and corneal epithelial and endothelial cell lines. The morphology, growth properties, and viability of cells grown on PA6/12 nanofibers were comparable with those grown on plastic. LSCs labeled with the fluorescent dye PKH26 and grown on PA6/12 nanofibers were transferred onto the damaged ocular surface, where their seeding and survival were monitored. Cotransfer of LSCs with MSCs, which have immunosuppressive properties, significantly inhibited local inflammatory reactions and supported the healing process. The results thus show that nanofibers prepared from copolymer PA6/12 represent a convenient scaffold for growth of LSCs and MSCs and transfer to treat SC deficiencies and various ocular surface injuries.

A rapid separation of two distinct populations of mouse corneal epithelial cells with limbal stem cell characteristics by centrifugation on percoll gradient.

PURPOSE: To detect and isolate cells with stem cell (SC) characteristics in the limbus of the mouse. METHODS: Limbal tissues from BALB/c mice were trypsin-dissociated and separated on the gradient Percoll (Fluka, Buchs, Switzerland). Several fractions were isolated and characterized by real-time PCR for the presence of limbal SC markers and differentiation markers of corneal epithelial cells by flow cytometry for the determination of the side-population (SP) phenotype and growth properties in vitro. RESULTS: Cells retained in the lightest fraction (40% Percoll) and in the densest fraction (80% Percoll) of the gradient were both enriched for populations with a high expression of the SC markers ABCG2 and Lgr5 and also expressing the SP phenotype. However, the lightest fraction (representing approximately 12% of total limbal cells) contained cells with the strongest spontaneous proliferative capacity and expressed the corneal epithelial differentiation marker K12. In contrast the densest fraction (<7% of original cells) was K12 negative and contained small nonspontaneously proliferating cells, which instead were positive for p63. Unexpectedly, cells from this fraction had the highest proliferative activity when cultured on a 3T3 feeder cell monolayer. CONCLUSIONS: These findings demonstrate the presence of two distinct populations of corneal epithelial cells with limbal SC characteristics, based on differential expression of the keratin-specific marker K12 and transcription factor p63, and suggest a difference in developmental stage of the two populations, with the K12(-)p63(+) population being closer to the primitive limbal SC.