Guillermo Amescua

Modified Simple Limbal Epithelial Transplantation Using Cryopreserved Amniotic Membrane for Unilateral Limbal Stem Cell Deficiency

PURPOSE To report the results of simple limbal epithelial transplantation using a double-layered cryopreserved amniotic membrane graft for the management of unilateral limbal stem cell deficiency. DESIGN Retrospective case series. METHODS Four consecutive patients with unilateral partial (2 eyes) and total (2 eyes) limbal stem cell deficiency secondary to ocular surface burns (2 eyes), trauma (1 eye) and conjunctival melanoma treatment (1 eye) underwent modified simple limbal epithelial transplantation at Bascom Palmer Eye Institute. Preoperative and postoperative visual acuity and quality of corneal epithelium were evaluated. RESULTS The patients were followed up for a mean ± standard deviation of 7.5 ± 1.3 months. The donor eye returned to a healthy state in all patients. All patients had significant improvement in visual acuity and resolution of ocular pain in the affected eye. Regular corneal epithelium and a quiet ocular surface were obtained in all patients by a median of 4 weeks. CONCLUSIONS Compared with the currently used surgical techniques for management of limbal stem cell deficiency, simple limbal epithelial transplantation seems to be a safe, reproducible, and effective alternative. The use of a double layer allows more protection for the explant without impacting outcomes. Also, the use of cryopreserved amniotic membrane allows surgeons to perform this procedure in the Unites States. More cases with longer follow-up will be needed to assess the outcomes further.

Effect of CXCL-1/KC production in high risk vascularized corneal allografts on T cell recruitment and graft rejection

Background. The survival rate of corneal allografts in high-risk vascularized corneal bed recipients is poor, similar to vascularized solid organ allografts. Although the early induction of selective chemokines in solid organs is required for the optimal recruitment of T cells into rejecting allografts, little is known about the role of these chemokines in high risk corneal allografts. Methods. Orthotopic corneal allotransplants were performed in low-risk (nonvascularized) and high-risk (vascularized) C57BL/6 (H-2b) recipients using Balb/c (H-2d) donors. Intragraft production of CXC chemokines was measured by Luminex and enzyme-linked immunosorbent assay on corneal transplant extracts at different times after surgery. Rabbit anti-KC serum was used to test its role in high risk corneal allograft survival. Results. Early upregulation of CXCL1/KC occurs 3 days after transplantation in high risk allograft only. Moreover, the T-cell chemoattractants, CXCL9/Mig and CXCL10/IP10, are produced late (day 10) after surgery and their production correlates with the recruitment of CD4 T cells into the graft. Furthermore, in vivo neutralization of CXCL1/KC with anti-KC sera results in increased graft survival and decreased recruitment of T cells into high-risk allografts. Conclusion. We propose that a high risk vascularized cornea behaves like a vascularized solid organ transplant. The early production of CXCL1/KC is crucial to the induction of T-cell chemoattractants necessary for the recruitment of allospecific CD4 T cells into the graft. In vivo neutralization of CXCL1/KC represents a potential novel therapy that could be used to increase the survival rate of high-risk vascularized corneal allografts.

Autologous simple limbal epithelial transplantation for unilateral limbal stem cell deficiency: multicentre results

Purpose To report outcomes of autologous simple limbal epithelial transplantation (SLET) performed for unilateral limbal stem cell deficiency (LSCD) at multiple centres worldwide. Methods In this retrospective, multicentre, interventional case series, records of patients who had undergone autologous SLET for unilateral LSCD, with a minimum of 6 months of follow-up, were reviewed. The primary outcome measure was clinical success, defined as a completely epithelised, avascular corneal surface. Kaplan–Meier survival curves were constructed and survival probability was calculated. A Cox proportional hazards analysis was done to assess association of preoperative characteristics with risk of failure. Secondary outcome measures included the percentage of eyes achieving visual acuity of 20/200 or better, percentage of eyes gaining two or more Snellen lines and complications encountered. Results 68 eyes of 68 patients underwent autologous SLET, performed across eight centres in three countries. Clinical success was achieved in 57 cases (83.8%). With a median follow-up of 12 months, survival probability exceeded 80%. Presence of symblepharon (HR 5.8) and simultaneous keratoplasty (HR 10.8) were found to be significantly associated with a risk of failure. 44 eyes (64.7%) achieved a visual acuity of 20/200 or better, and 44 eyes (64.7%) gained two or more Snellen lines. Focal recurrences of pannus were noted in 21 eyes (36.8%) with clinical success. Conclusion Autologous SLET is an effective and safe modality for treatment of unilateral LSCD. Clinical success rates and visual acuity improvement are equal to or better than those reported with earlier techniques.

Assessment of rose bengal versus riboflavin photodynamic therapy for inhibition of fungal keratitis isolates.

PURPOSE To compare the in vitro effect of rose bengal and riboflavin as photosensitizing agents for photodynamic therapy (PDT) on fungal isolates that are common causes of fungal keratitis. DESIGN Experimental study. METHODS Three isolates (Fusarium solani, Aspergillus fumigatus, Candida albicans) recovered from patients with confirmed fungal keratitis were used in the experiments. Isolates were grown on Sabouraud-Dextrose agar, swabbed, and prepared in suspension, and 1 mL aliquots were inoculated onto test plates in triplicate. Test plates were separated into 5 groups: Group 1, no treatment; Group 2, 0.1% rose bengal alone; Group 3, 518 nm irradiation alone; Group 4, riboflavin PDT (riboflavin + 375 nm irradiation); and Group 5, rose bengal PDT (rose bengal + 518 nm irradiation). Irradiation was performed over a circular area using either a green light-emitting diode (LED) array (peak wavelength: 518 nm) or an ultraviolet-A LED array (peak wavelength: 375 nm). Test plates were irradiated with an energy density of 5.4 J/cm(2). Later, plates were placed in a 30 C incubator and observed for growth. RESULTS Rose bengal-mediated PDT successfully inhibited the growth of all 3 fungal isolates in the irradiated area. All other groups exhibited unrestricted growth throughout the plate. CONCLUSIONS Rose bengal-mediated PDT successfully inhibited the growth of 3 types of fungi. No other experimental groups, including riboflavin-mediated PDT, had any inhibitory effect on the isolates. The results might be useful for the treatment of patients suffering from corneal infection.

Limbal stem cell transplantation: current perspectives

Regeneration of the corneal surface after an epithelial insult involves division, migration, and maturation of a specialized group of stem cells located in the limbus. Several insults, both intrinsic and extrinsic, can precipitate destruction of the delicate microenvironment of these cells, resulting in limbal stem cell deficiency (LSCD). In such cases, reepithelialization fails and conjunctival epithelium extends across the limbus, leading to vascularization, persistent epithelial defects, and chronic inflammation. In partial LSCD, conjunctival epitheliectomy, coupled with amniotic membrane transplantation, could be sufficient to restore a healthy surface. In more severe cases and in total LSCD, stem cell transplantation is currently the best curative option. Before any attempts are considered to perform a limbal stem cell transplantation procedure, the ocular surface must be optimized by controlling causative factors and comorbid conditions. These factors include adequate eyelid function or exposure, control of the ocular surface inflammatory status, and a well-lubricated ocular surface. In cases of unilateral LSCD, stem cells can be obtained from the contralateral eye. Newer techniques aim at expanding cells in vitro or in vivo in order to decrease the need for large limbal resection that may jeopardize the “healthy” eye. Patients with bilateral disease can be treated using allogeneic tissue in combination with systemic immunosuppressive therapy. Another emerging option for this subset of patients is the use of noncorneal cells such as mucosal grafts. Finally, the use of keratoprosthesis is reserved for patients who are not candidates for any of the aforementioned options, wherein the choice of the type of keratoprosthesis depends on the severity of the disease. In summary, limbal stem cell transplantation improves both vision and quality-of-life in patients with ocular surface disorders associated with LSCD, and overall, the use of autologous tissue offers the best results. Future studies aim at improving cellular expansion and finding different sources of stem cells.

Use of Intraocular Videoendoscopic Examination in the Preoperative Evaluation of Keratoprosthesis Surgery to Assess Visual Potential

PURPOSE To determine the clinical utility of intraocular videoendoscopy examination for the evaluation of the retina and optic nerve in patients being considered for a Boston type I keratoprosthesis (KPro). DESIGN Interventional case series study. METHODS Ten patients with a history of corneal blindness caused by failed penetrating keratoplasty (PK) and inability to accurately assess visual potential were included in this study. Ophthalmologic examination, B-scan ultrasonography, and pars plana videoendoscopy were carried out to assess the retina and optic nerve before KPro. RESULTS Posterior segment examination was successfully used to evaluate the retina and optic nerve of all patients with opaque corneas. Out of 10 patients that underwent endoscopic examination, 3 (30%) were considered to be adequate candidates for KPro surgery and 7 (70%) were not. This was based on visualized retinal disease and/or optic nerve pathology. Of the 3 patients that underwent KPro surgery, all of them had a significant improvement of vision, including counting fingers to 20/100, hand motion to 20/5, and light perception to 20/80, as suggested by the endoscopy preoperative examination. No complications of the endoscopy procedure were observed. CONCLUSIONS This report demonstrates the successful use of intraocular videoendoscopy to rule out threats to a good visual outcome for patients being considered as candidates for KPro. Direct visualization of the posterior segment can be part of the preoperative algorithm in the decision process of performing a KPro surgery in patients when visual potential is questionable.

Minor ipsilateral simple limbal epithelial transplantation (mini-SLET) for pterygium treatment

We describe a novel surgical technique for pterygium removal taking advantage of the properties of amniotic membrane and limbal epithelial stem cells. A total of 10 eyes underwent pterygium excision with amniotic membrane coverage of the bare sclera and placement of pieces of limbal epithelium in a linear fashion in the affected limbal area covered by a second amniotic membrane using fibrin glue. After up to 8 months of follow-up, there were no signs of early recurrence or sight-threatening complications. The minor ipsilateral simple limbal epithelial transplantation technique for the treatment of pterygium requires less tissue than the conventional conjunctival autograft, leaving healthy conjunctiva if needed for another procedure in the future and offers the advantages of epithelial stem cells, which in the long term may reduce the rate of recurrence significantly.

Role of steroids in the treatment of bacterial keratitis

Bacterial keratitis can lead to severe visual impairment from corneal ulceration, subsequent scarring, and possible perforation. The mainstay of treatment is topical antibiotics, whereas the use of adjunctive topical corticosteroid drops remains a matter of debate. Herein, we review the rationale for and against the use of topical corticosteroids and we assess their effectiveness and safety in the published randomized controlled trials that have evaluated their role as adjunctive therapy for bacterial corneal ulcers. In the largest study to date, the Steroids for Corneal Ulcers Trial, topical corticosteroid drops were neither helpful nor harmful for the 500 participants as a whole. However, subgroup analyses suggested that topical corticosteroids may be beneficial upon early administration (within 2–3 days after starting antibiotics) for more central corneal ulcers with poorer vision at presentation, for invasive Pseudomonas strains, and for non-Nocardia ulcers. These results are discussed within the limitations of the study.

Management of Patients With Confirmed and Presumed Mucous Membrane Pemphigoid Undergoing Entropion Repair

PURPOSE To describe the outcomes and medical management necessary to achieve successful lid surgery in patients with biopsy-confirmed and presumed mucous membrane pemphigoid. DESIGN Retrospective, interventional case series. METHODS We included patients with positive biopsy results and cases with a typical clinical active bilateral presentation with negative biopsy results but classic features. We identified 11 operated eyes of 7 patients with lid malposition resulting from mucous membrane pemphigoid, particularly cicatricial entropion, that required surgical correction. Complete ophthalmologic history and examination were performed. The main outcome measures were control of ocular inflammation, progression of disease, and surgical success. RESULTS A bandage lens was used in 8 (72.7%) eyes to protect the cornea while immunosuppression and control of disease activity were achieved. Control of ocular inflammation before lid surgery was achieved in all cases. Immunosuppressive treatment before lid surgery was used in all cases for a mean of 15.1 months (range, 8.2 to 33.1 months) and after surgery for a mean of 6.6 months (range, 3.0 to 11.2 months). The oral immunosuppressive drugs used were mycophenolate and cyclophosphamide. Prednisone was used concomitantly in 4 (57%) patients. Full surgical success was achieved in all patients, with 1 patient requiring a second intervention because of residual disease. The mean postoperative follow-up period was 20.8 months (range, 6.0 to 30.5 months). CONCLUSIONS Successful entropion repair in patients with mucous membrane pemphigoid can be achieved if control of inflammation is attained before the procedure. Ocular surface protection while achieving disease control is essential in the management of these patients.

Candida Endophthalmitis After Descemet Stripping Automated Endothelial Keratoplasty With Grafts From Both Eyes of a Donor With Possible Systemic Candidiasis

Purpose: To report 2 cases with late postoperative Candida albicans interface keratitis and endophthalmitis after Descemet stripping automated endothelial keratoplasty (DSAEK) with corneal grafts originating from a single donor with a history of presumed pulmonary candidiasis. Methods: Two patients underwent uncomplicated DSAEK by 2 corneal surgeons at different surgery centers but with tissue from the same donor and were referred to the Bascom Palmer Eye Institute with multifocal infiltrates at the graft–host cornea interface 6 to 8 weeks later, and anterior chamber cultures that were positive for the same genetic strain of C. albicans. Immediate explantation of DSAEK lenticules and daily intracameral and instrastromal voriconazole and amphotericin injections failed to control the infection. Thus, both patients underwent therapeutic penetrating keratoplasty with intraocular lens explantation, pars plana vitrectomy, and serial postoperative intraocular antifungal injection. Results: Both patients are doing well at 2 years postoperatively with best-corrected vision of 20/20 and 20/30+ with rigid gas permeable lenses. One patient required repeat optical penetrating keratoplasty and glaucoma tube implantation 1 year after the original surgery. Literature review reveals that donor lenticule explantation and intraocular antifungals are often inadequate to control fungal interface keratitis, and a therapeutic graft is commonly needed. Conclusions: Interface fungal keratitis and endophthalmitis due to infected donor corneal tissue is difficult to treat, and both recipients of grafts originating from the same donor are at risk of developing this challenging condition.