Assessment of retinal function in cataract patients by a combination of laser interferometry and conventional display methods to measure contrast sensitivity

Abstract

Conventional methods of measuring retinal function are dependent on the optics of the eye. Therefore, an optical opacity such as a cataract that obstructs the normal optical transmission of light can prevent measurement of retinal function. In some cases a laser interferometer designed to bypass the effects of the optics of the eye may be employed to measure retinal function without interference due to the optical components. In this study we compare contrast sensitivity functions determined by laser interferometry and conventional display methods for cataract and normal eyes. Comparison of laser and monitor contrast sensitivity functions indicates that for these cataract patients interferometric measurements show a normal retinal function, whereas similar measures using the traditional display system (monitor) show considerable loss of visual function. The extent to which contrast sensitivity was limited by the lens of the eye is indicated by the ratio of laser and monitor contrast thresholds. In general, the laser interferometry technique demonstrates that relatively minor cataracts decrease the contrast transfer function of the eye' optics over a range of spatial frequencies.