Comparison of High Acuity Scores on Snellen and Ortho-Rater Tests
NAVAL MEDICAL RESEARCH LAB NEW LONDON CT
Pagination or Media Count:
Visual acuity involves the ability of the eye to discriminate contours as measured by the size of the target item. Since contours can take many forms, it is to be expected that differently shaped contours will yield different values of acuity from the same individual. Evidence of this has been found in many studies, among which the AGO Studies in Visual Acuity indicates from the factor analysis that a test may involve as many as four factors retinal resolution, brightness discrimination, simple form perception, and letter perception. Of these, retinal resolution accounts for most of the variance in test scores and is the primary factor considered in visual acuity measurements. While size is paramount, the indication is that the same item size is not equivalent from one contour to another.
- Anatomy and Physiology