Conjunctival-corneal melt in association with carotid artery stenosis

Rosalind MK Stewart1, Say Aun Quah1, Dan Q Nguyen2, Stephen B Kaye11Royal Liverpool University Hospital, Liverpool, UK; 2Bristol Eye Hospital, Bristol, UKPurpose: To report a case of severe conjunctival-corneal melt in association with carotid artery stenosis.Methods: Observational case report.Results: A 76-year-old man with a history of bilateral severe carotid artery occlusion and nonarteritic ischemic optic neuropathy developed a spontaneous bulbar conjunctival defect. Despite intensive lubrication, and attempts at surgical closure including an amniotic membrane patch graft, it progressed with subsequent adjacent corneal perforation. Thorough investigations revealed no underlying disease, except markedly delayed episcleral vessel filling on anterior segment fluorescein angiography.Conclusions: Neovascularisation is a known factor in the inhibition of ulceration. In light of the findings in this report, ocular ischemia should be considered as a cause or contributing factor in the differential diagnosis of conjunctival-corneal melt.Keywords: conjunctival melt, corneal melt, ocular ischemia, carotid artery stenosi

Human Conjunctival Stem Cells are Predominantly Located in the Medial Canthal and Inferior Forniceal Areas.

PURPOSE: The conjunctiva plays a key role in ocular surface defence and maintenance of the tear film. Ex vivo expansion of conjunctival epithelial cells offers potential to reconstruct the ocular surface in cases of severe cicatrising disease, but requires initial biopsies rich in stem cells to ensure long-term success. The distribution of human conjunctival stem cells, however, has not been clearly elucidated. METHODS: Whole human cadaveric conjunctiva was retrieved and divided into specific areas for comparison. From each donor, all areas from one specimen were cultured for colony-forming efficiency assays and immunocytochemical studies; all areas from the other specimen were fixed and paraffin embedded for immunohistochemical studies. Expression of CK19, p63, and stem cell markers ABCG2, ΔNp63, and Hsp70 were analyzed. Results were correlated to donor age and postmortem retrieval time. RESULTS: Conjunctiva was retrieved from 13 donors (26 specimens). Colony-forming efficiency and expression of stem cell markers ABCG2, ΔNp63, and Hsp70 in cultures and ABCG2 in fixed tissue were all consistently demonstrated throughout the tissue but with highest levels in the medial canthal and inferior forniceal areas (P < 0.01 for each). Both increasing donor age and longer postmortem retrieval times were associated with significantly lower colony-forming efficiency, stem cell marker expression in cell cultures and ABCG2 expression in fixed tissue. CONCLUSIONS: Biopsies from the medial canthus and inferior forniceal areas, from younger donors, and with short postmortem retrieval times offer the greatest potential to developing conjunctival stem cell-rich epithelial constructs for transplantation

Development of a Poly-epsilon-lysine Contact Lens for Drug Delivery in the Management of Fungal Keratitis

Purpose: The purpose of this study was to develop a more efficient drug delivery device to overcome the limitations of current drop therapy for the treatment of fungal keratitis. Methods: Amphotericin B (AmpB), 0 to 30 μg/mL, was associated with a poly-ε-lysine (pεK) hydrogel. Fungicidal effect against Candida albicans was assessed at 18 and 42 hours by optical density (OD600) and growth on agar. Tear film dilution effect was mimicked by storage of AmpB pεK gels in 3.4 mL sterile PBS for 24 hours prior to fungal incubation. Drug elution over 96 hours was evaluated by HPLC, and drug stability was tested while associated with the gel by OD600 up to 48 hours. Lack of cytotoxicity toward the HCE-T corneal epithelial cell line was assessed over 7 days. Results: AmpB pεK gels show fungicidal activity in normal conditions (0.057 OD600, SD 0.003, P < 0.005) and in the presence of horse serum (0.048 OD600, SD 0.028 P < 0.005) at 18 hours. The drug release profile was above therapeutic levels (0.188 μg/mL) for up to 72 hours. Tear dilution had no significant effect at higher concentrations of AmpB (3 to 10 μg/mL). AmpB pεK gels were not cytotoxic to the HCE-T cell line. Conclusions: We demonstrated that AmpB pεK gels confer sustained therapeutic antifungal activity for at least 48 hours without corneal epithelial cell line cytotoxicity, suggesting their potential for in vivo use as an antifungal bandage contact lens. This could avoid the need for intensive topical medication in the treatment of fungal keratitis

Specific decellularized extracellular matrix promotes the plasticity of human ocular surface epithelial cells

The ocular surface is composed of two phenotypically and functionally different epithelial cell types: corneal and the conjunctival epithelium. Upon injury or disease, ocular surface homeostasis is impaired resulting in migration of conjunctival epithelium on to the corneal surface. This can lead to incomplete transdifferentiation toward corneal epithelial-like cells in response to corneal basement membrane cues. We show that corneal extracellular matrix (ECM) proteins induce conjunctival epithelial cells to express corneal associated markers losing their conjunctival associated phenotype at both, mRNA and protein level. Corneal epithelial cells behave the same in the presence of conjunctival ECM proteins, expressing markers associated with conjunctival epithelium. This process of differentiation is accompanied by an intermediate step of cell de-differentiation as an up-regulation in the expression of epithelial stem cell markers is observed. In addition, analysis of ECM proteins by laminin screening assays showed that epithelial cell response is laminin-type dependent, and cells cultured on laminin-511 showed lower levels of lineage commitment. The phosphorylation and proteolysis levels of proteins mainly involved in cell growth and differentiation showed lower modifications in cells with lower lineage commitment. These observations showed that the ECM proteins may serve as tools to induce cell differentiation, which may have potential applications for the treatment of ocular surface injuries