Vision Measured by the Vimetrics CVA Compared With Chart Testing Under Similar Luminance and Contrast Conditions

Cataract, Maculopathy, Refractive Error

visual acuity, contrast sensitivity, cataract, maculopathy

Purpose of The Study: The purpose of this study is the following: A)To gather age-related normative visual acuity data for the Vimetrics Central Vision Analyzer (CVA, Vimetrics, LLC, Media, Pa) B)To gather visual acuity data for patients with known ocular problems, including cataract and maculopathy. C)To correlate and compare the CVA visual acuity findings with the acuity measured with standard LogMAR acuity charts viewed under similar conditions of contrast and lighting

The measurement of visual acuity involves the determination of the smallest high contrast target that can be resolved by the patient. Classically, this has been approached by the use of letter style optotypes, each having successively smaller stroke and gap resolution. More recently, the arrangements of letter charts have been redesigned with a logarithmic scale and with attention being paid to the uniformity of other effects such as crowding or of the choice of optotype. The resultant Ferris-Bailey-Lovie chart has become a standard for acuity testing, especially for clinical research. The letters of such acuity charts have a 0.1 logMAR step progression (1.26 X) between lines and have 5 letters per line. It has been noted that the logMAR chart could have greater resolution with finer steps between the lines and with improved repeatability by converting to a letter-by-letter scoring system. While these advances have improved the resolution and reliability of acuity measures, they require relatively cumbersome wall charts and do not provide any of the advantages of an interactive program that would enable a threshold to be approached by stimulus presentation on both the seeing as well as non-seeing sides. The Vimetrics CVA is an interactive computer device that measures threshold visual acuity by presenting a Landolt-C with the gap randomly tumbled in one of 4 positions to which the patient responds with a response pad. The threshold is approached in a logarithmic, staircase fashion to define the test subject's acuity threshold with a resolution similar to letter by letter scoring in chart testing but with the ability to rapidly test under a number of conditions of luminance and contrast that simulate activities of daily living. The CVA determination of visual acuity under six conditions of contrast and lighting will be compared with that acquired by logMAR chart testing under similar conditions.

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Austria, United States