Schematic eye models for simulation of patient visual performance.

Purpose: To determine if model eyes can simulate the visual performance of normal human eyes under conditions of varying low myopic blur, pupil size, and contrast.

Methods: High and low contrast Bailey-Lovie logMAR visual acuity (VA) of three normal eyes of three subjects were measured for four artificial pupil sizes and ten levels of myopic defocus. Simulated visual acuities were then determined for three model eyes--the Indiana Eye with no spherical aberration, the Indiana Eye with average spherical aberration, and the Kooijman Eye--by generating optically aberrated VA charts for each testing condition using Visual Optics Lab software by Sarver and Associates, Inc, and having the subjects read high resolution printouts of these charts using a 3-mm pupil and optimal spectacle correction. The correlation between real VA and simulated VA was then plotted and a regression line calculated.

Results: Slopes for the Indiana Eye, Indiana Eye with spherical aberration, and Kooijman Eye were 0.98, 0.98, and 1.01 for high contrast, and 0.92, 0.67, and 0.75 for low contrast, respectively. The r2 values were 0.73, 0.74, and 0.77, for high contrast, and 0.69, 0.40, and 0.50 for low contrast, respectively. Under low contrast conditions the Indiana Eye VA was significantly closer to the real VA than that of the other two models (P<.0003).

Conclusion: Visual performance can be simulated by eye models. The simple single surface Indiana Eye with no spherical aberration best modeled both high and low contrast visual acuity.