Oxyopia Abstract

February 24, 2006
Friday, 4 PM
489 Minor Hall

Shirkant Bharadwaj, PhD
Vision Science Graduate Program, School of Optometry, University of California, Berkeley
Host: Cliff Schor

Title

Neural control strategies of human ocular accommodation

Abstract

Ocular accommodation, the ability of human eye to change its optical power, operates by changing the curvature of crystalline lens in response to constriction of the ciliary muscle. The past century has seen important advances concerning the biomechanical properties of the structures involved in accommodation and the changes in these structures that contribute to presbyopia. However, there have been limited advances in our knowledge of the neural control of accommodation. My talk will mainly focus on how behavioral observations of the first- and second-order dynamics of accommodation step responses were used to investigate the neural control of accommodation. In the first part of the talk, I will show empirical observations that suggest that accommodation step responses are driven by an initial pre-programmed pulse innervation followed by a defocus-feedback controlled step innervation and that these neural control signals are altered in presbyopia to compensate for the age-related increase in viscosity of the lens. In the second part of the talk, I will focus on the up-coming accommodating-intraocular lens (A-IOL) technology that attempts to restore accommodation in presbyopes. Using computer simulations, I will show that implanting an A-IOL in a presbyope will result in highly unstable accommodation responses and that recalibration of the neural control signals will help restore optimal response characteristics.

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