A New Aspect of Keratoconus

Hypermobility of the joints is a frequent finding in patients who have keratoconus. Twenty two of 44 patients (50 per cent) presenting in 1973 were found to have hypermobility of joints (mainly Ehlers-Danlos syndrome 11 or mitis type). The significance of this finding is discussed in relation to the recent discovery by Kim and Hassard (1972) that three corneal buttons from keratoconus patients were deficient in glucose-6-phcsphate dehydrogenase (G-6-PDH) levels. Also the deficiency of hydroxylysine in collagen taken from two children by Pinnell et alii (1.972) showed for the first time that a generalized heritable disorder of connective tissue has a biochemical basis. Their description of the eyes of these children suggests that they had keratoconus. The hypothesis is made that keratoconus is often a part of a generalized heritable disorder of connective tissue due to a defect in collagen metabolism causing a weakness in its structure.