Abstract
Purpose :
The purpose of our current study is to investigate the histological features and establish the presence of distinctive morphological patterns of epithelial alterations in keratoconus.
Methods :
The clinical histories and microscopic slides of 56 patients with keratoconus were studied retrospectively. The paraffin blocks were retrieved, sectioned in 5-µm-thick sections and stained with hematoxylin and eosin (H&E). The histological slides were evaluated using bright field microscopy. Central and peripheral corneal epithelial thickness was measured, and morphological features of the epithelium were studied in order to identify differences and possible patterns of alteration.
Results :
Three distinctive patterns of epithelial alteration of the central cornea were established. The most common pattern accounting for 41% (23/56) of the cases was characterized by statistically significant increase in central corneal epithelial thickness (mean 68±5µm, p<0.0001) with hypertrophy and pronounced hydropic changes (17 cases) or hyperplasia with focal hydropic change (6 cases). The hydropic changes ranged from focal cellular swelling to patchy vacuolar degeneration to complete ballooning with cell loss and partial intraepithelial and subepithelial detachment. The second most common pattern 32% (18/56) constituted of markedly reduced central epithelial thickness (mean 19.9±1.2µm, p<0.001) with frank atrophy (8 cases), or atrophy with focal cell swelling (10 cases). The most rare pattern accounting for 27% (15/56) of the cases revealed unchanged central epithelial thickness (mean 36.5±1.75µm, p<0.001) with morphological features of the central corneal epithelium comparable to those of the peripheral epithelium. There were no hypertrophic, hydropic, hyperplastic, or atrophic alterations present in this subset of patients.
Conclusions :
Central corneal epithelium in keratoconus responds with characteristic compensatory changes varying from hypertrophy with hydropic changes, to hyperplasia, to atrophy, which are responsible for the formation of distinctive histological patterns. These patterns could potentially have diagnostic and prognostic value. Future work is necessary to establish the significance and detectability of these morphological patterns by current advanced imaging methods, as well as their application as predictive factors in the progression of the disorder.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.