Retinal sensitivity and adaptation in pediatric patients

Abstract

A two-alternative forced-choice preferential looking psychophysical procedure was used to measure dark-adapted thresholds of 79 patients whose medical and ophthalmological conditions raised the possibility of scotopic retinal disorders. The average dark-adapted threshold first obtained from 48 patients, who eventually manifested diseases affecting the scotopic retina, was higher than the average threshold of the 31 patients without scotopic disease. Among the 48 patients with scotopic disease, most (40 out of 48) had abnormal electroretinographic b-wave amplitudes; in 23 scotopic b-waves were present but attenuated to less than or equal to 30% of the normal mean; no scotopic b-wave responses could be elicited from 17. In only 6 of the 40 patients with abnormal scotopic b-waves were the psychophysical thresholds elevated greater than 2.5 log units. That is, the scotopic b-wave is often sensitive to the effects of the retinal disorders of our patients, but the wider range of psychophysical responses permits investigation and analysis of retinal function. In the 13 patients for whom b-wave thresholds could be determined, b-wave and psychophysical thresholds were not correlated, further suggesting that electroretinographic and psychophysical data provide complementary information about retinal function. Thus the psychophysical techniques are suitable for investigation of the functional organization of diseased pediatric retinas. In patients with retinal disorders psychophysical procedures have enabled description of temporal and spatial summation and adaptation to steady background lights. Examples of results of spatial summation and background adaptation studies are presented in this report.