Role of accommodation in experimental myopia in chicks.

We compared the morphology of the accommodative apparatus in myopic and control chicks using light microscopy and scanning and transmission electron microscopy. Results indicate no significant difference in ciliary muscle and ciliary fold structure between control chick eyes and eyes in which at least 10 D of myopia was induced by the application of a translucent goggle. Based on the assumption that sustained tonic contraction of the accommodative apparatus in the myopic eye would lead to morphological differences, we conclude that the myopic eye is not accommodating excessively during development. These results, in combination with previous findings concerning the role of accommodation in experimental myopia, strongly indicate that accommodation does not play a significant role in this type of experimental myopia in chicks.