The rhodopsin content of human eyes

PURPOSE. To measure the total amount of rhodopsin in human eyes across the life span and to test the hypothesis that the rhodopsin content of infants' and the elderly's eyes is lower than at other ages. METHODS. Rhodopsin was extracted from retinal and pig ment epithelial fract ions of 196 eyes of 102 donors, ages 27 weeks' gestation through 94 years, using quantitative procedures. To recover photopigment bleached bg; unavoid able light exposure, the fractions from 78 eyes were incubated with 9-cis r etinal. The total photopigment (retinal plus pigment epithelial fractions) per eye was examined for significant changes with age, using the higher val ue from pairs of eyes. RESULTS. The median rhodopsin content of the higher eye of adults is 6.45 n moles (range, 3.33-10.84 nmoles) with 8 nmoles or more recovered from 28% o f all adult eves. The rhodopsin content of infants' eyes (<12 months postte rm) is significantly lower than that of older individuals and increases wit h age. After infancy, no change with age is found. For both infants and adu lts, 9-cis retinal significantly increases the amount of photopigment recov ered without reducing the variance in the amount of photopigment recovered. The rhodopsin content is estimated to be 50% of the median adult amount ea rly in infancy, approximately 5 weeks postterm (95% confidence interval, 0- 10 weeks postterm). CONCLUSIONS. A developmental increase in rhodopsin content occurs during in fancy. Thereafter rhodopsin content remains constant. The amount of rhodops in recovered from human eves is quite variable. Bleaching alone cannot expl ain the variability.