Abstract
Abstract: :
Purpose: Test the hypothesis that rod cell sensitivity (S) is low in infants with variants of albinism. In normal infants, S is scaled by rhodopsin content, and in animals with variants of albinism, rhodopsin content is reported to be low. Visual inattention and delayed visual maturation are recognized features of infants with albinism. Methods: Infants (n=10; median age 15 weeks) were referred for ERG testing because of profound visual inattention, and subsequently determined to have variants of albinism, that is tyrosinase gene mutations/polymorphisms. All were term born, healthy infants. S was calculated by fit of a model of the activation of phototransduction to the a-waves. Other receptoral and post-receptoral ERG components were also analyzed. Results: S was within normal limits for age in every infant with a variant of albinism. The mean value of S in those with variants of albinism (Mean=5.43; SD=2.74 sec-2) and normal infants (n=47; mean=4.58; SD=1.85 sec-2) did not differ significantly. All other receptoral and post-receptoral components were normal in the infants with variants of albinism. Conclusion: No evidence of low rod cell sensitivity, or by inference, of low rhodopsin content, is found in these visually inattentive infants with variants of albinism. This is at odds with the animal results possibly because of species and procedural differences.
Keywords: visual development: infancy and childhood • visual development • photoreceptors