Psychophysical estimates of ocular media density of human infants.

The ocular media densities of eleven 10-week-old infants and of 10 adults were estimated from dark adapted thresholds measured using a two alternative forced choice preferential looking method. The estimated media density at 400 nm derived from these thresholds ranged from 0.55 to 1.00 (median 0.75) log units for infants, and from 1.35 to 1.69 (median 1.46) log units for young adults. This indicates media density increases significantly (0.71 log units) between infancy and adulthood. These data allow more complete specification of the retinal stimulus for quantitative analysis of infants' retinal function.