Corneal trauma from overnight wear of rigid or soft contact lenses

To evaluate the mechanical or biochemical insult to the cornea induced by overnight rigid gas permeable (RGP) or soft contact lens (SCL) wear, punctate, stipple staining and corneal blotting were evaluated by biomicroscopy in a group of 23 subjects who participated in a single overnight in-laboratory test session. The soft lens-wearing corneas typically showed greater area of staining along with corneal blotting in comparison to RGP-wearing corneas which showed smaller areas of corneal staining, even in the presence of RGP adherence, and no corneal blotting. We investigated the effect of hypoxia on corneal staining by having subjects wear an RGP lens of Dk = 150 on one eye and a soft lens of Dk = 9 on the fellow eye. Pachometry measurements immediately following eye opening showed an average central corneal swelling of 5 percent for the RGP lens-wearing eye and an average of 11 percent for the SCL-wearing eye. It is likely that the differences in corneal effects of RGP and SCL overnight lens wear are the result of differences in the nature of rigid versus soft contact lens adherence.