Development of refraction and strabismus.

Research on the etiology and causes of refractive errors has become a very active field of study during the past few years. Most of this research has focused on myopia. But hyperopia and astigmatism are also being examined both in comparison to myopia and in their own right. Animal models have also been developed for the study of experimentally induced myopia and hyperopia. These studies demonstrate the chain of neural and molecular events that occurs in induced myopia and hyperopia with increasing precision. In the future, these results may elucidate the mechanisms that underlie the refractive errors seen in human populations. Research into the development of strabismus has not progressed with the same vigor. The links among hyperopia, accommodative convergence, and strabismus are well established. Numerous neural, oculomotor, and subjective correlates of strabismus are now well established, but there has been a failure to develop the experimental paradigms needed to demonstrate the causal relations among these different factors.