Differential diagnosis of corneal oedema assisted by in vivo confocal microscopy

The purpose of this study was to demonstrate microstructural differences be tween clinically similar, but aetiologically different, cases of corneal oe dema in four subjects. In vivo confocal microscopy highlighted oedema of th e basal epithelium, prominent nerve-keratocyte interactions, and typical 'e pithelialization' of the endothelium in a case of iridocorneal endothelial syndrome; however, a similar microstructural appearance was observed in a c ase of presumed herpetic disciform keratitis. The latter diagnosis was subs equently revised on this basis. Confocal examination of Fuchs' endothelial dystrophy demonstrated oedema of the basal epithelium, prominent wing cells , anterior stromal alterations, fibrosis of Descemet's membrane and a typic al 'strawberry' appearance of the endothelium. In contrast, in vivo microst ructural examination of bilateral keratoconus with hydrops confirmed oedema mainly involving the epithelium and anterior stroma. In vivo confocal micr oscopy allows the clinician to observe the living cornea at a microstructur al level and to better diagnose and differentiate borderline or unusual cas es of corneal oedema.