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

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 vivo using a vital dye-based imaging technique, offering a practical tool for assessing endothelial health in settings where in vivo imaging may be impractical or unavailable.

Central corneal buttons (8-mm) were collected post-mortem from 50 cats (100 eyes) and processed within 6 h of death or euthanasia. The endothelium was stained with 0.25% trypan blue and 0.5% alizarin red (pH 4.2) and imaged using light microscopy at 20× 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 (< 10 vs. ≥ 10 years) and sex, with correlations to age explored via Spearman testing.

Median (±SEM; range) values across all eyes were as follows: MCA 352 ± 10 μm² (104-458), MCD 2766 ± 196 cells/mm² (2250-10 183), polymegathism 14% ± 0.3% (11-20), and pleomorphism 85% ± 0.8% (60-94). Older cats had significantly larger MCA (367 vs. 330 μm²; p < 0.001), lower MCD (2625 vs. 2970 cells/mm²; p < 0.001), and higher pleomorphism (86% vs. 82%; p =f). Age strongly correlated with MCD (r = -0.653, p < 0.001) and MCA (r = 0.593, p < 0.001).

This ex 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.