A COMPARISON OF BINOCULAR SUMMATION IN THE PERIPHERAL VISUAL-FIELD INYOUNG AND OLDER PATIENTS

Purpose. To measure binocular and monocular thresholds to a light dete ction task in order to investigate binocular summation in the central and peripheral visual fields. The study also aims to investigate any d ifferences in the magnitude of binocular summation in young and older subjects with healthy eyes. Methods. Binocular and monocular threshold s were measured at eccentricities of 0, 5, 15, 25 and 40 degrees nasal ly and temporally, using the Humphrey Field Analyser. Binocular summat ion ratios were computed as the binocular sensitivity divided by the ' 'best'' monocular sensitivity. Results. Binocular and monocular sensit ivities declined with increasing eccentricity. Binocular summation rat ios were shown to be significantly higher for the younger group compar ed to the older group at all eccentricities. Conclusions. Using this t est, the binocular performance is shown to be lower for the older grou p at all eccentricities. Results are discussed in terms of age-related cortical cell loss and increased monocular sensitivity difference.