ABSTRACT Thirty‐five myopic subjects were fitted with rigid gas‐permeable lenses for 6 months of extended wear (EW). These lenses had an average oxygen transmissibility of 37 ⋉ 10–9 (cm ⋉ ml ⋉ O2)/(s ⋉ ml ⋉ mm Hg). For six monthly morning visits subjects reported with one eye patched; corneal thickness, corneal curvature, refractive error, endothelial photomicroscopy, and slitlamp examinations were done on both eyes. The average morning corneal swelling was 5.9 ± 3.3%. Corneal curvature showed 0.24 ± 0.44 D flattening in the steep meridian and 0.20 D steepening in the flat meridian. Spectacle refraction and corrected visual acuity changes were small in the spherical and cylindrical components. Complications that were important clinically included 10% lens adherence syndrome, 20% superficial limbal keratitis, 6.5% epithelial microcysts, and some increase in endothelial polymegath‐ism. No infections, red eye responses, or infiltrative keratitis were observed during the 6‐month follow‐up period. These results suggest that hard‐lens EW is feasible and that lenses with this Dk/L value will meet oxygen requirements for many patients; however, some patients will require lenses of higher oxygen transmissibility to avoid undesirable complications.
Polse et al. (Sun,) studied this question.