The effect of contact lens wear on the ocular surface changes in keratoconus

To investigate the effects of contact lens wear or the keratoconic shape itself on the changes in the ocular surface in keratoconus.

Forty-two patients (84 eyes) were enrolled in this study and divided into four groups. Group 1 comprised 22 eyes with keratoconus that had been wearing rigid gas-permeable (RGP) contact lenses for an average of 5.54 +/- 2.11 years. Group 2 comprised 24 myopic eyes that had been wearing RGP contact lenses for 6.42 +/- 1.79 years. Group 3 comprised 20 eyes with keratoconus without any contact lens wear. Group 4 comprised 18 healthy eyes that were used as controls. The ocular surface changes were evaluated by determining the tear film breakup time and performing conjunctival impression cytology. The goblet cell densities, nucleus-to-cytoplasm ratio, and epithelial cell morphology in the four groups were compared with optical microscopy in the high-power field.

The tear film breakup times in groups 1 and 2 were significantly lower than those in groups 3 and 4. The goblet cell densities were 5.49 +/- 1.75 and 5.82 +/- 1.63 in groups 1 and 2, respectively, which were significantly lower (P < 0.05) than the 8.79 +/- 1.42 and 10.24 +/- 2.10 in groups 3 and 4, respectively. There were no statistically significant differences in the goblet cell densities, nucleus-to-cytoplasm ratios, and epithelial cell morphologies between groups 1 and 2 and groups 3 and 4.

The ocular surface changes in keratoconus may be directly related to contact lens wear and not to the keratoconic shape itself.