An Ex Vivo Morphometric Study of the Feline Corneal Endothelium (100 Eyes).

Abstract

BACKGROUND: The feline corneal endothelium plays a critical role in maintaining corneal clarity, yet little is known about its baseline morphology and age-related changes. This study aimed to assess endothelial morphology ex&#xa0;vivo using a vital dye-based imaging technique, offering a practical tool for assessing endothelial health in settings where in&#xa0;vivo imaging may be impractical or unavailable. METHODS: Central corneal buttons (8-mm) were collected post-mortem from 50 cats (100 eyes) and processed within 6&#x2009;h of death or euthanasia. The endothelium was stained with 0.25% trypan blue and 0.5% alizarin red (pH&#x2009;4.2) and imaged using light microscopy at 20&#xd7; magnification. Morphometric analysis included mean cell density (MCD), mean cell area (MCA), polymegathism (coefficient of variation of cell area), and pleomorphism (% hexagonality). Statistical analyses assessed differences by age (<&#x2009;10 vs. &#x2265;&#x2009;10&#x2009;years) and sex, with correlations to age explored via Spearman testing. RESULTS: Median (&#xb1;SEM; range) values across all eyes were as follows: MCA 352&#x2009;&#xb1;&#x2009;10&#x2009;&#x3bc;m(104-458), MCD 2766&#x2009;&#xb1;&#x2009;196&#x2009;cells/mm(2250-10&#x2009;183), polymegathism 14%&#x2009;&#xb1;&#x2009;0.3% (11-20), and pleomorphism 85%&#x2009;&#xb1;&#x2009;0.8% (60-94). Older cats had significantly larger MCA (367 vs. 330&#x2009;&#x3bc;m; p&#x2009;<&#x2009;0.001), lower MCD (2625 vs. 2970&#x2009;cells/mm; p&#x2009;<&#x2009;0.001), and higher pleomorphism (86% vs. 82%; p&#x2009;=f). Age strongly correlated with MCD (r&#x2009;=&#x2009;-0.653, p&#x2009;<&#x2009;0.001) and MCA (r&#x2009;=&#x2009;0.593, p&#x2009;<&#x2009;0.001). CONCLUSIONS: This ex&#xa0;vivo approach enables detailed evaluation of feline corneal endothelial morphology, revealing clear age-related trends. The technique is practical and cost-effective for veterinary and translational research, with potential to support studies of endothelial health and dysfunction across species.