A 1-year evaluation of the feasibility of the use of gas-permeable rigid
lenses for extended wear was carried out, using two different materials. Forty subjects were entered into the study. Fifteen were fitted with the
Polycon II lens and another 15 with the Boston IV lens. These two groups wore the
lenses on a weekly basis for the duration of the study. Two other groups, the controls, were fitted with the same types of
lenses as the experimental groups, but wore the
lenses on a daily basis. All
lenses were made to the Syntex specifications for the
Polycon lens and the groups were comparable with regard to age, sex,
refractive error,
corneal astigmatism, and any pre-existing ocular pathology. All subjects carried out the same care regimen for their
lenses and were examined after 24 h, 1 week, 1 month, 3 months, 6 months, and 1 year. Examinations performed at the follow-up visits were to determine any clinically observable effects of lens wear in each patient in all groups. The results of the study suggest that the extended wear of gas-permeable rigid materials is a viable option. However, the results also indicate that extended wear is not without problems, and these need to be studied more fully before the use of gas-permeable rigid
lenses for extended wear can be recommended.