The design and prescription of multifocal lenses for civil pilots

The aging (presbyopic) pilot has difficulty with near vision which can be a serious problem in the cockpit because of the complexity and uniqueness of his visual tasks. Numerous individual studies have been reported, but the aviation industry and vision care professionals do not have available to them a set of guidelines to permit the optimum fitting of spectacles for civil aviation pilots. In this study the cockpit vision environment was studied in ten contemporary aircraft. Twenty-five pilots of seven of these aircraft types participated in a spectacle design study. Experimental spectacles were designed for each pilot and evaluated for performance. Problems of pilot acceptance of reading aids, custom designing to the geometry of a given aircraft, balancing of the visual gains from complex designs versus difficulties in use and manufacture have been analyzed. Results of this study should be of value for human factors engineering, vision testing and accurate prescription for the presbyopic pilot.