Histopathological study of 49 cases of keratoconus

Keratoconus is a bilateral and asymmetrical corneal ectasia. The pathophysiology of this disorder has yet to be fully elucidated. The purpose of our study was to document the prevalence of the most common morphological features of keratoconic corneas. A retrospective analysis of 49 cases diagnosed as keratoconus between 2001 and 2006 was undertaken. Histopathological reports were reviewed to obtain data such as age and gender. Specimens were fixed in 10% buffered paraformaldehyde solution for 24h, bisected through the centre of the button, and embedded in paraffin. Sections were stained with haematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) for light microscopic examination. The studied group was composed of 29 men and 20 women. Age at the time of the penetrating keratoplasty was 39±14 years (mean ± standard deviation). Forty of the 49 specimens (82%) presented with epithelial thinning. Other common features of keratoconus included breaks in Bowman’s layer in 35 (71%), compaction of the stromal collagen fibres in 31 (63%), and folds in Descemet’s membrane in 31 (63%) cases. Other less common histopathological findings were: presence of superficial iron deposits in 14 (29%), deep stromal scarring in 12 (24%), epithelial scarring in 11 (22%), endothelial cell loss in 11 (22%), and breaks in Descemet’s membrane in nine (18%) cases. Some of the histopathological findings associated with keratoconus are subtle. It is important to be aware of them in order to properly confirm the clinical diagnosis.