The ultrastructure of superficial hypertrophic dendriform epitheliopathy after keratoplasty

To report the ultrastructure of superficial hypertrophic dendriform epitheliopathy (SHDE).

Two epithelial and two penetrating keratoplasty specimens from 1 patient were examined by electron microscopy. Tissue was processed for light and transmission microscopy.

Striking intraepithelial aggregates corresponded to zones affected clinically. These stained heavily with toluidine blue and were composed ultrastructurally of electron-dense, microfibillar aggregates. The thin and degenerate epithelium contained a dense cytoplasm, lucent spaces, numerous microfilaments and glycogen granules. Basal cells showed infrequent hemidesmosomes. Basement membrane contained long-spacing collagen and Bowman's layer was replaced by a collagenous pannus, separated from the epithelium by large lucent spaces. Keratocytes within the pannus were degenerate, while collagen fibres were sparse and intermixed with microfilaments and long-spacing collagen. Large quantities of proteoglycans were present in pannus and stroma. Descemet's membrane was arranged in multiple lamellae containing basement membrane material, long-spacing collagen and microfilaments.

SHDE is a distinct syndrome that occurs after keratoplasty in patients with tear dysfunction. It is speculate that it represents an aberrant form of keratinisation due to exposure and poor wetting in a denervated cornea. Chronic epithelial change leads to secondary reactive changes in the stroma.