Effects of Ageing on Spatial Aspects of the Pattern Electroretinogram in Male and Female Quail

This study deals with age-related functional changes in the eye of quail. Measurements of lens refractive state and transmission, as well as pupil diameter, showed that the quail's eye became more myopic with increasing age, but no change could be detected in lens transmission and pupil diameter. Three aspects of the pattern electroretinogram (PERG) were studied after correcting for ocular refraction: (i) spatial characteristics (visual acuity and contrast sensitivity); (ii) maximal amplitude; and (iii) peak latency. The PERG results suggested that the visual acuity was age-independent for both sexes. However, the contrast sensitivity of the old quail (16-20 months) was much lower (1.5-3 times) than that of the young (3-6 months) at low to intermediate (< 2 c/d), but not at high spatial frequencies. The peak latency of the PERG response was 3-4 msec longer in the old birds compared with the young, while the maximal amplitude of the PERG response was age-independent. These results clearly suggested that at least some of the age-induced changes are located in the neural retina.