Myopia in the eye of developing chicks following monocular and binocular lid closure.

It has recently been reported that lid closure in monkeys, whether monocularly or binocularly performed, leads to an axial enlargement of the eye, resulting in a high myopia (Wiesel and Raviola, i?77. 1978). Using a similar experimental procedure in monkeys Von Noorden and Crawford (1978) were unable to repeat these results. Slight myopia was also obtained in tree shrews similarly operated. although it was not attributed merely to an axial change (Sherman et al., 1977) and mild myopia (1.0 to -2.0 D) has been preliminarily reported for the deprived eye of monocularly sutured cats (Wilson and Sherman, 1977). The presence of myopia in lid sutured chicks has already been described (Yinon er al., 1980; Wallman et al., 1978); in addition, Jensen and Matson (1957) have reported enlargement of the eye of chicks due to continuous incandescent illumination. In the present paper we describe the development of axial enlargement accompanied by a flattening of the cornea, following lid suture in chicks. Such a cornea1 flattening tends to optically antagonize the myopic enlargement.