ABNORMAL EPITHELIAL FRAGILIGY IN DIABETES AND IN CONTACT LENS WEAR

The fragility of the corneal epithelium of diabetic subjects and of contact lens wearers was compared with the fragility of normals. Diabetics had a damage threshold of 14.9 mg. In hard lens wear the threshold was 20.33 mg, whilst in soft lens wear it was 15.3 mg. These values compare with the control value of 28.3 mg are significantly depressed (P< 0.05). There is some evidence to suggest that the abnormal fragility of the epithelium in all groups is due to hypoxia of the epithelium. The sensitivity of the cornea of diabetics is also depressed. Touch thresholds, measured at the periphery, are elevated by about 85% over the comparable control group. This is considerably greater than the threshold elevation for touch reported elsewhere to occur in diabetes, and so the abnormal corneal sensitivity may be partly caused by a local epithelial abnormality.