Sensitivity and fragility in keratoconus

38 persons with various degrees of keratoconus were examined. Using the photokeratoscope an index of the severity of the cone was established and compared to a group of normal eyes. Sensitivity was measured in the centre and periphery of the cornea. It was found to be significantly lower than in normal eyes and those eyes wearing contact lenses exhibited the lowest sensitivity. There was no correlation between peripheral CTT (Corneal Touch Threshold) and the severity of keratoconus, but there was a significant correlation between central CTT and severity, though only for the group of eyes not wearing contact lenses. Corneal fragility was also found to be greater in keratoconus than in normal eyes and more so in those eyes wearing contact lenses. There was a significant correlation between the severity and the fragility.