The objective of the project is to study the role of ocular accommodation in maintaining the state of misalignment in monkeys with strabismus. Strabismus is an early developmental disorder in which the visual axes of the two eyes are not aligned resulting in loss of binocular stereopsis and depth perception. It is estimated that about 4% of all children have some form of strabismus making it a significant public health issue. Of this in more than 35% of the cases the problem is related to the errors in accommodation system. Ocular accommodation, convergence and miosis are three motor responses known to play an important role in clear and single binocular vision. There is a known cross-link between accommodation and convergence system and this interdependency has been studied for its possible role in the etiology of strabismus. However there is a lack of clear understanding of the moment-to-moment interactions between the accommodation and vergence systems in strabismus and how this might affect the dynamic state of strabismus. Dynamic measurement of accommodation along with simultaneous eye movement information can provide information about the stability of accommodative response and also provide insight into the neural control of accommodation in strabismus. Remote infrared photorefraction technique will be used to measure binocular accommodation, the scleral search coil system to measure accurate binocular eye movements, and single electrode extracellular neural recording to measure neural activity from Edinger Westphal (EW) nucleus while the monkey performs behavioral tasks that vary accommodative demand or the state of misalignment. These methodologies will be used to address the following specific goals: 1) to identify correlations between dynamic changes in state of misalignment and dynamic changes in accommodative state;2) to determine the role of the Edinger Westphal nucleus in maintaining the state of misalignment in sensory induced strabismus. Understanding the role of the accommodative drive to the vergence system and the underlying neural mechanism that might influence the state of strabismic misalignment will enable us to better understand the etiology of strabismus and manage it. The broader objective of the postdoctoral fellowship training is to provide the applicant necessary technical training in accommodation control and its interaction with the oculomotor system in strabismus. The expectation is that this training will help in transitioning into an independent researcher.
Four percent of all the children in the United States have strabismus making it a significant health issue, yet there is a lack of clear understanding of the underlying neurobiological mechanism. The goal of this project is to understand the role of the accommodative drive to the vergence system and the underlying neural mechanism that might influence the state of strabismic misalignment. This will enable us to better understand the etiology of strabismus and manage it.