MEDICAL APPLICATIONS OF SCLERAL CONTACT-LENSES .2. GAS-PERMEABLE SCLERAL CONTACT-LENSES

The indications and outcome of the wear of gas-permeable (GP) scleral contact lenses in 118 eyes of 85 patients attending a Scleral Contact Lens Clinic during a 5-year period from July 1988 to June 1993 were an alysed. Ninety-nine eyes (83.9%) were originally fitted with PMMA lens es and were subsequently changed to GP lenses, whereas 19 (16.1%) were fitted with GP lenses from the outset. The mean duration of GP sclera l lens wear was 15.3 months, with a range between 3 and 58 months. The indications for refitting the cases previously wearing PMMA scleral l enses with GP material were related to problems of chronic hypoxia. Th irty-three eyes (26.8%) had previous episodes of corneal oedema, and o f the 27 that had a minimum of 3 months' follow-up, none experienced f urther episodes of oedema. Of the 32 eyes (26%) that had developed cor neal vascularisation associated with PMMA scleral lens wear, two eyes were noted to have significant vessel regression after a period of GP wear, whereas in the remainder of cases, vessels remained static and n onprogressive. Thirty additional eyes (24.2%) experienced inadequate w ear times associated with discomfort, and in these eyes the change to GP scleral lenses produced a statistically significant reduction in th e inability to wear lenses beyond 4 h (p < 0.05).