Vision development in the monocular individual: implications for the mechanisms of normal binocular vision development and the treatment of infantile esotropia.

PURPOSE

The purpose of this research is to study the vision development in monocular individuals so as to better understand normal binocular vision development and to refine the treatment of infants with infantile esotropia.

METHODS

Thirty-six subjects with one clinically normal eye and one eye with no vision (no light perception or history of enucleation) are studied. In addition to measurement of standard parameters of development such as visual acuity, measurement of motion processing is made by both optokinetic and electrophysiologic techniques. A comparison is made of vision development among three populations: the monocular population, the normal population, and patients with a history of infantile esotropia. Such comparison is made to study the relative effects of interruption of binocularity and binocular competition. The monocular population represents individuals who have interruption of binocularity, whereas the infantile esotropia population has both interruption of binocularity and binocular competition.

RESULTS

The OKN data suggest that the monucular population is more similar to the normal population than the esotropia population. The electrophysiologic data shows a statistically significant difference in the three populations. Motion processing is more fully developed in the monocular population than in the infantile esotropia population when compared to the normal population.

CONCLUSIONS

1. The development of motion processing appears to be particularly vulnerable to abnormal experience during the first year of life. 2. Monocular subjects have a less abnormal motion processing system when compared to patients with infantile esotropia even when monocularity is congenital. 3. The results indirectly support the premise that prealignment alternate occlusion is of benefit to the patient with infantile esotropia prior to realignment. 4. Development of the motion processing system does not necessarily parallel the development of other binocular functions.