ALBINO CHICKENS -- AN APPROPRIATE REFRACTIVE ERROR MODEL FOR HUMAN ALBINISM?

Michel Wong

Abstract

PURPOSE. We studied the refractive profile of albino chicks as a potential animal model for human albinism which is typically associated with abnormal refractive errors although their origin is unclear. METHOD. White-Leghorn chicks exhibiting an oculocutaneous, tyrosine negative, form of albinism (WLA) were hatched from fertilized eggs (n=5), and monitored over the first 6 weeks of development. Refractive errors were measured by retinoscopy. In addition, external and retinal photographs were taken and retinal tissue processed for histological analysis. Normal White-Leghorns (n=4) were raised under identical conditions for comparison.

RESULTS. Our results indicate important parallels with albinism in humans: albino chicken eyes (1) contain no melanin- thus the iris and pecten appear pink and the choroidal blood vessels are clearly visible through the retina; (2) are very photophobic; (3) have poor vision- pecking during feeding is very inaccurate; and (4) show abnormal refractions. Refractive errors (left eye data) ranged from-8.0 to-0.25 D at 3 weeks compared to 1.75 to 3.00 D for control chicks and there was an overall myopic bias (means:-3.73 cf. 2.35 D). The WLA also had higher than normal astigmatism (means: 1.05 D cf. -0.31 D at 3 weeks), which was generally against-the-rule. They also showed only limited emmetropization over the 6 week monitoring period, with eyes generally remaining myopic (means:-0.4 D cf. 1.78 D for controls). The WLAs do not have nystagmus.

CONCLUSIONS. The similarities between WLA and human albino eyes supports the use of the WLA as an animal model to study the effect of albinism on refractive development in humans.

Details

Year: 2001

Program Number: Poster 98

Author Affiliation: University of California

Co-Authors: Caroline Blackie, Chun Xie, William Payne

Co-Author Affiliation: University of California, University of California, Michigan State University

Room: Exhibit Hall C