Purpose: : To evaluate corneal structure in eyes with keratoconus by using in vivo confocal microscopy.
Methods: : In a prospective institutional study, 48 eyes of 24 consecutive patients with keratoconus were examined by in vivo confocal microscopy. Forty-four eyes of 22 healthy subjects served as the control. The main outcome measures were qualitative and quantitative changes encountered at confocal microscopy examination.
Results: : In the keratoconus group, in vivo confocal microscopy findings included elongated, exfoliating superficial epithelial cells; brightly reflective material deposition within the basal epithelial cells; prominent, thickened subbasal nerves; structural changes in subbasal nerve fibers; pronounced reflectivity and irregular arrangement of stromal keratocytes; structurally abnormal anterior stromal keratocyte nuclei; folds in the anterior, mid, and posterior stroma; folds in Descemet's membrane; pleomorphism and enlargement of endothelial cells; and endothelial guttata. No such abnormal findings were present in the control group. There were significant differences between the two groups in terms of the mean basal epithelial, anterior and posterior stromal keratocyte densities, the mean basal epithelial cell area, and the mean endothelial cell hexagonality percentages.
Conclusions: : Quantitative and qualitative structural changes were observed in all corneal layers in eyes with keratoconus by using slit-scanning confocal microscopy. The changes at all levels were more prominent in eyes with severe keratoconus. This noninvasive in vivo technique may prove to be useful in the diagnosis and follow-up of keratoconus and in the understanding of its pathophysiology.