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

## TL;DR

This study examines the feline corneal endothelium using a staining and imaging method, revealing how its structure changes with age.

## Contribution

A practical ex vivo method for assessing feline corneal endothelial morphology is introduced and validated.

## Key findings

- Older cats show significantly larger cell area and lower cell density in the corneal endothelium.
- Age strongly correlates with changes in cell density and area, indicating age-related endothelial changes.
- The technique is cost-effective and suitable for veterinary and translational research.

## Abstract

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.