A COMPARISON OF BINOCULAR SUMMATION IN YOUNG AND OLDER PATIENTS

Binocular and monocular contrast sensitivities were measured at two sp atial frequencies of 1 and 6 c/deg in 8 young (mean age 22.6 +/- 3.8 y ears) and 18 older subjects with normal healthy eyes (mean age 58.4 +/ - 7.3 years). Data were analysed as binocular summation ratios defined as binocular CS/'best eye'CS. Binocular summation ratios were higher for the younger group (1.46 and 1.48 for 1 and 6 c/deg respectively) c ompared to the older group who demonstrated a spatial frequency depend ence (1.31 and 1.13 at 1 c/deg and 6 c/deg respectively). The results are discussed in terms of age-related cortical cell loss and increased monocular sensitivity differences between the two eyes.