The role of topical insulin in ocular surface restoration: A review.

Corneal epithelial defects are one of the most common ocular disorders. Restoring corneal integrity is crucial to reduce pain and regain function, but in cases of neurotrophic or desensitized corneas, healing can be significantly delayed. Treating neurotrophic corneas is challenging for ophthalmologists, and surgical intervention is often indicated to manage refractory cases that are unresponsive to medical therapy. Over the last decade, as more expensive therapeutics reach the market, topical insulin has returned to the forefront as an affordable option to improve corneal wound healing. There is still a paucity of data on the use and the efficacy of topical insulin, with no consensus regarding its indications, preparation, or posology. Here we review the literature on topical insulin for corneal and ocular surface pathologies, with a focus on the current evidence, its mechanisms of action, and its safety profile. Additionally, we share our experience in the field and provide a potential framework for future research.

Ocular Surface Homeostasis After Scleral Lens Usage.

OBJECTIVES: The aim of this prospective study is to examine the effects of 5 hours of well-fitted, mini-scleral contact lens (mini-SL) wear on the tear film cytokine expression in healthy eyes. METHODS: Twenty-three healthy participants were included in the study. One eye of each participant was selected at random, and a mini-SL measuring 16.5 mm in diameter was fitted by an experienced contact lens specialist. The contact lens remained in place for 5 hours. Precorneal tear fluid was collected using capillary tubes at three different time points: baseline before SL insertion (T0), after 5 hours of SL wear (T1), and 3 hours after SL removal (T2). The concentration of 40 inflammatory cytokines at the three different time points was determined using multiplex bead assay. RESULTS: Mini-scleral lens wear did not result in significant changes in the cytokine-to-protein ratio after 5 hours of wear on a healthy eye. CONCLUSIONS: Although a well-fitted mini-SL reduces the rate at which the precorneal tear film is refreshed, 5 hours of lens wear did not appear to significantly affect the tears cytokine-to-protein ratio, suggesting that scleral lenses have minimal impact on corneal cytokine expression.

Outcomes of Human Leukocyte Antigen-Matched Allogeneic Cultivated Limbal Epithelial Transplantation in Aniridia-Associated Keratopathy-A Single-Center Retrospective Analysis.

PURPOSE: To assess the efficacy and safety of human leukocyte antigen-matched allogeneic cultivated limbal epithelial stem cell grafts in the treatment of aniridia-associated keratopathy (AAK). METHODS: Six eyes of 6 patients with severe AAK received an allogeneic stem cell graft between January 2010 and March 2017. Anatomical and functional results were assessed at 6 months, 1 year, 2 years, and the final follow-up visit available. Safety analysis was performed by considering all perioperative and postoperative adverse events and additional surgeries required during the follow-up period. RESULTS: The mean follow-up was 53.6 months (range 24-104 months). In most patients (80%), there was an early improvement of the keratopathy postoperatively, which slowly regressed during longer follow-up. At the final follow-up, 4 of the eyes were graded as failure and 1 eye was graded as partial success. Grading the sixth eye was not possible because of an adverse event. None of the patients maintained a total anatomical success in the long-term. Only 1 patient maintained a modest improvement in best-corrected visual acuity from hand motion to counting fingers. Four serious adverse events were recorded in 2 patients. CONCLUSIONS: Severe AAK remains a challenging condition to manage. Transplantation of allogenic ex vivo cultivated limbal stem cells may provide a temporary improvement in ocular surface stability, but anatomical and functional results are poor in the long-term. The eyes are prone to adverse events, and any surgical treatment should take this into consideration.

Development and Validation of an Open-Source Grading Tool for Outcome Assessment in Limbal Stem Cell Treatment.

PURPOSE: To design a grading system and validate an open-source tool to improve objective quantification and follow-up of limbal stem cell deficiency (LSCD) after treatment. METHODS: A custom-made web-based grading system was developed for grading stem cell deficient eyes, termed the "Vascularisation, Haze, and Integrity" tool. For validation purposes, 60 corneal slit-lamp images of 30 limbal stem cell deficient eyes were graded by 3 groups of examiners: 3 corneal specialists (group A), 3 ophthalmologists with an expertise other than cornea (group B), and 3 nonclinicians (group C). The intragrader and intergrader agreement was evaluated using Fleiss weighted kappa coefficients and concurrent assessment of interrater and intrarater reliability (IRR) coefficients. RESULTS: The overall intergrader agreement was 0.78, 0.61, and 0.42 for superficial corneal vascularization, corneal haze, and epithelial integrity, respectively. All groups had good agreement for the vascularization parameter with the highest intergrader reliability in group A (IRR = 0.80) and the lowest in group C (IRR = 0.72). When assessing "haze," there was good agreement in groups A (IRR = 0.75) and B (IRR = 0.76) but low agreement in group C (IRR = 0.37). CONCLUSIONS: We report the development and evaluation of a novel method for grading results of limbal stem cell deficient eyes after treatment and provide this system as a free, open-source online tool. The grading tool offers an easy and standardized way of assessing the corneal surface in patients with LSCD, enables evaluation of progression over time, reduces assessment bias, and-if adopted universally-will harmonize outcome being reported between groups.

Short- and Long-Term Results of Xenogeneic-Free Cultivated Autologous and Allogeneic Limbal Epithelial Stem Cell Transplantations.

PURPOSE: To evaluate the short- and long-term success rates of xenogeneic-free cultivated limbal epithelial stem cell transplantation (CLET) for the treatment of limbal stem cell deficiency (LSCD). METHODS: Thirteen patients with LSCD underwent an autologous (n = 9) or allogeneic (n = 4) CLET. The primary end point was to assess the long-term anatomical success rate of transplanted grafts at a follow-up of at least 3 years, in comparison with the short-term outcomes. Secondary end points involved reviewing functional improvement, patient-reported symptoms, and change in percentage area of corneal vascularization in both short-term and long-term. RESULTS: The mean short- and long-term follow-up periods were 2.1 ± 0.38 years and 6.7 ± 1.81 years, respectively. The total anatomical success rate was 46.1% in the short-term, but it decreased to 23.1% in the long-term. A partial success rate of 30.8% was observed in both short- and long-term, and the failure rate increased from 23.1% to 46.1%. The mean percentage of vessel area decreased from 12.11% ± 5.29% preoperatively to 7.82% ± 6.70% in the short-term and increased to 8.70% ± 6.32% in the long-term. There was a significant improvement in best-corrected visual acuity (P = 0.044) in the short-term although not in the long-term (P = 0.865). CONCLUSIONS: This study shows that anatomical and functional success rates of CLET decrease over time. We believe that the decline of success is related to the extent of disease, cell origin, and lack of niche protection because subtotal LSCD and autologous donor cells confer a higher chance of success in the long-term.

Ethical issues in living-related corneal tissue transplantation.

The cornea was the first human solid tissue to be transplanted successfully, and is now a common procedure in ophthalmic surgery. The grafts come from deceased donors. Corneal therapies are now being developed that rely on tissue from living-related donors. This presents new ethical challenges for ophthalmic surgeons, who have hitherto been somewhat insulated from debates in transplantation and donation ethics. This paper provides the first overview of the ethical considerations generated by ocular tissue donation from living donors and suggests how these might be addressed in practice. These are discussed in the context of a novel treatment for corneal limbal stem cell deficiency. This involves limbal cell grafts which are transplanted, either directly or after ex vivo expansion, onto recipient stem cell-deficient eyes. Where only one eye is diseased, the unaffected eye can be used as a source of graft tissue. Bilateral disease requires an allogenic donation, preferably from a genetically related living donor. While numerous papers have dealt with the theory, surgical approaches and clinical outcomes of limbal stem cell therapies, none has addressed the ethical dimensions of this form of tissue donation.

Anterior eye surface changes following miniscleral contact lens wear.

PURPOSE: To quantify the effect of short-term miniscleral contact lens wear on the anterior eye surface of healthy eyes, including cornea, corneo-scleral junction and sclero-conjuctival area. METHODS: Twelve healthy subjects (29.9 ±â€¯5.7 years) wore a highly gas-permeable miniscleral contact lens of 16.5 mm diameter during a 5-hour period. Corneo-scleral height profilometry was captured before, immediately following lens removal and 3 h after lens removal. Topography based corneo-scleral limbal radius estimates were derived from height measurements. In addition, elevation differences in corneal and scleral region were calculated with custom-written software. Sclero-conjuctival flattening within different sectors was analysed. RESULTS: Short-term miniscleral lens wear significantly modifies the anterior eye surface. Significant limbal radius increment (mean ±â€¯standard deviation) of 146 ±â€¯80 µm, (p = 0.004) and flattening of -122 ±â€¯90 µm in the sclero-conjuctival area, (p << 0.001) were observed immediately following lens removal. These changes did not recede to baseline levels 3 h after lens removal. The greatest anterior eye surface flattening was observed in the superior sector. No statistically significant corneal shape change was observed immediately following lens removal or during the recovery period. CONCLUSIONS: Short-term miniscleral contact lens wear in healthy eyes does not produce significant corneal shape changes measured with profilometry but alters sclero-conjuctival topography. In addition, sclero-conjuctival flattening was not uniformly distributed across the anterior eye.

Scleral asymmetry as a potential predictor for scleral lens compression.

PURPOSE: To identify the position and magnitude of lens compression due to short-term miniscleral contact lens wear, as well as evaluating the usefulness of scleral asymmetry as a predictor for scleral lens decentered compression. METHODS: Fourteen healthy subjects (mean ± S.D.: 29.2 ± 6.0 years) wore a highly gas-permeable spherical haptic miniscleral contact lens during a 5-h period. Corneo-scleral height Fourier profilometry was captured using an Eye Surface Profiler (www.eaglet-eye.com) before and immediately after lens removal. Scleral asymmetry, lens compression location and magnitude were processed using custom-made algorithms, both globally and for scleral quadrants. RESULTS: Miniscleral contact lenses do not set uniformly on the ocular surface, with the largest decentration seen along the horizontal meridian. The greatest flexural stress exerted by the lens on the ocular surface occurs at the point coinciding with the inner diameter landing point of the lens and not with its overall diameter. Scleral asymmetry was significantly correlated with compression location (R = 0.71, p = 0.002) and compression magnitude (R = 0.81, p < 0.001), showing its potential as compression predictor. CONCLUSION: Larger amounts of scleral asymmetry will lead to more decentration of spherical haptic scleral lenses. Objective and accurate methods, like the one presented here, could help the practitioner prevent cases of scleral blanching or discomfort due to an excessive compression by the lens.

Diagnostic Challenges in Nocardia Keratitis.

OBJECTIVE: To present a case of diagnostic confusion in Nocardia keratitis in a contact lens wearer and to illustrate the characteristic clinical findings of this rare entity. METHODS: Case report of Nocardia keratitis that was mistaken for acanthamoeba, herpetic, and fungal keratitis in three tertiary corneal referral centers before the correct diagnosis of Nocardia infection was made. RESULTS: A 29-year-old contact lens wearer was referred to our hospital for a contact lens-associated bacterial keratitis, not improving under standard bacterial treatment. Biomicroscopy revealed a circular corneal ulcer and pinhead lesions arranged in a wreath pattern. Initial scraping revealed no positive cultures and confocal microscopy findings were suspicious for fungal keratitis. Only after a poor response to protozoal and fungal treatment, and a negative herpes serology, Nocardia was suspected. This suspicion was confirmed with a positive culture and the topical amikacin and ciprofloxacin were started. The infiltrate responded promptly and resolved, leaving a small corneal scar and a good visual recovery. CONCLUSION: Because of its infrequent occurrence and its variable clinical picture, Nocardia keratitis is easily misdiagnosed. Although a rare entity, this infection should be added to the differential diagnosis in contact lens-related keratitis not responding to first-line antibiotics and presenting with patchy anterior stromal infiltrates.

A method for quantifying limbal stem cell niches using OCT imaging.

AIMS: To evaluate the efficacy of Fourier domain-optical coherence tomography (FD-OCT) in imaging and quantifying the limbal palisades of Vogt and to correlate these images with histological findings. METHODS: The superior and inferior limbal region of both eyes of 50 healthy volunteers were imaged by FD-OCT. Images were processed and analysed using Matlab software. In vitro immunofluorescent staining of a cadaveric donor limbus was analysed to correlate the presence of stem cells in the visualised structures. RESULTS: FD-OCT could successfully visualise limbal crypts and the palisades of Vogt in the limbus region. Fluorescent labelling confirmed the presence of stem cells in these structures. The mean palisade ridge width (ΔPR) and the mean interpalisade epithelial rete peg width (ΔERP) were both of the order of 72 µm, leading to a palisade density (PD) of about 7.4 palisades/mm. A significant difference in ΔPR, ΔERP and PD was seen between the inferior and superior sides of the right eye and the superior sides of the left and right eye(p<0.05.). A significant influence of iris colour on parameters ΔPR, ΔERP and PD was found, and of age on PD and ΔERP (p<0.05). CONCLUSIONS: In vivo OCT imaging is a safe and effective modality to image the limbus and can be used to visualise the palisades of Vogt. Image processing using Matlab software enabled quantification and density calculation of imaged limbal palisades of Vogt. This technique may enhance targeted limbal biopsies for transplantation.