Intersubject difference in corneal edema response to hypoxia

A common clinical observation is that some patients are more prone to the development of corneal edema than others. To test the validity of this observation, 30 subjects each wore an experimental hydrogel lens designed to stress corneal metabolism by reducing oxygen availability and thereby producing measurable amounts of corneal edema. The corneal edema response varied from 20.3 (3.7%) to 55.1 microns (12.2%) after 3 hr of opened-eye lens wear. Mean intrasubject reliability was +/- 3 microns (0.6%). Corneal edema response to the experimental lens was well correlated with corneal edema response to a conventional thin hydrogel lens (r = 0.83). These results support the conclusion that some patients are more prone than others to developing corneal edema and that these patients can be identified by measuring corneal thickness changes after a 3-hr wearing trial with a thick HEMA lens of standard dimensions.