A four stage phase I effort will be conducted to develop a screening technique for the dark focus, compare the dark focus with visual contrast sensitivity, investigate the underlying relationship between the dark focus and measured visual contrast sensitivity, and develop a plan to develop optimal pilot selection algorithm'; for visual characteristics. The dark focus will be measured by an optometer to be constructed according to a design selected during stage 1. Current candidates are the laser optometer and the vernier optometer. Data will be collected during stage 2 for both the dark focus and visual contrast sensitivity. The analyses will be directed at elucidation of potential variations in contrast sensitivity as a result of preferred focal distance-target distance mismatches.
