Effect of Fluctuating +G sub z Exposure on Rigid Gas-Permeable Contact Lens Wear.

摘要

Rigid gas-permeable (RGP) contact lenses may offer some significant advantages over soft lenses for aircrew in the aerospace environment. These advantages include crisper visual acuity, allowing for more oxygen to the cornea, and a lower complication rate. A primary concern of the high-performance aircraft crewmember is the possible displacement or actual dislodgment of the contact lens due to a rapid increase in gravitational forces. Soft contact lenses remained well centered on the cornea under high gravitoinertial (G) forces during previous testing on the USAFSAM centrifuge. This study was designed to determine how well RGP contact lenses position on the cornea during high G forces and the effect on visual acuity. Six ametropic subjects were fitted with lenses made from Pasifocon C material (specific gravity = 1.07). Two lens diameters (8.8-9.4. mm and 9.6-10.0 mm) were compared for centration. Visual acuity was measured at +1 Gz (baseline), +3 Gz, +4 Gz, +6 Gz, and +8 Gz from 3 acuity charts mounted in the gondola. All lenses, as estimated from the videotape, decentered down the z axis 2-3 mm at high +Gz. Acuities with the contact lenses were similar to the spectacle control rides. The RGP contact lenses fitted with relatively large diameters performed well in centrifuge testing. (RRH)