A four-surface schematic eye of macaque monkey obtained by an optical method.

Schematic eyes for four Macaca fascicularis monkeys were constructed from measurements of the positions and curvatures of the anterior and posterior surfaces of the cornea and lens. All of these measurements were obtained from Scheimpflug photography through the use of a ray-tracing analysis. Some of these measurements were also checked (and confirmed) by keratometry and ultrasound. Gaussian lens equations were applied to the measured dimensions of each individual eye in order to construct schematic eyes. The mean total power predicted by the schematic eyes agreed closely with independent measurements based on retinoscopy and ultrasound results, 74.2 +/- 1.3 (SEM) vs 74.7 +/- 0.3 (SEM) diopters. The predicted magnification of 202 microns/deg in one eye was confirmed by direct measurement of 205 microns/deg for a foveal laser lesion. The mean foveal retinal magnification calculated for our eight schematic eyes was 211 +/- (SEM) microns/deg, slightly less than the value obtained by application of the method of Rolls and Cowey [Experimental Brain Research, 10, 298-310 (1970)] to our eight eyes but just 4% more than the value obtained by application of the method of Perry and Cowey [Vision Research, 12, 1795-1810 (1985)].