Application of new technology to low vision

Abstract

A number of technological advances in low vision have been made in the last twenty years. The first part of this presentation deals with diagnostic methodology in low vision. From Sloan's letters for measurement of visual acuity, various logarithmic acuity charts have been derived for the assessment of distance visual acuity. Recent studies on low-vision patients also emphasize the importance of measuring visual acuity with low contrast charts. Some of these charts are discussed. In terms of retinal acuities, the optical principles of instruments including the retinometer, the visometer, and the potential acuity meter are reviewed. The clinical use of these instruments is covered. In addition to spatial frequency thresholds, measurement of contrast sensitivity provides another way in which low-vision patients’ vision can be assessed readily. Subtle changes of vision can be monitored by this technique. Illustrated clinical examples are given. The second part deals with optical treatment for low-vision problems. For example, the use of optical filters and prisms for certain low-vision patients is described. Some optoelectronic sensory aids are available at our Centre for Sight Enhancement. A description of one or two systems employing various optical and electronic components is given.