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J. R. Drover, A. E. Earle, K. H. B. House; A New Computer-Based Instrument to Measure Resolution Acuity, Contrast Sensitivity, and Vernier Acuity. Invest. Ophthalmol. Vis. Sci. 2010;51(13):969.
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© ARVO (1962-2015); The Authors (2016-present)
The assessment of functional vision in preschoolers is difficult as they often lack the attention span or cognitive capabilities to complete traditional tests. Given preschoolers’ fascination with computer games and computer-based instructional programs, a computer-based vision test would likely yield higher testability and more accurate scores. Thus, we developed a prototype computer-based instrument (CBI) of functional vision designed specifically for this age group. Here we examine the validity of this new instrument by comparing it to standard vision tests.
The CBI consists of a laptop computer connected to a calibrated, high-resolution monitor. It contains tests of resolution acuity, contrast sensitivity (CS), and vernier acuity in which a test stimulus, either a square wave grating (resolution acuity), a sine wave grating (CS), or a misaligned, striped star pattern (vernier acuity), is presented on the monitor at the top or bottom of the screen. Using newly written software, stimulus levels are controlled by the tester. To examine its validity, 31 adults (age=22.4±8.4y) were tested with the CBI and their grating acuity, CS, and vernier acuity scores were compared to those obtained with chart-based or card-based tests (Teller Acuity Cards [TAC], Functional Acuity Contrast Test [FACT], Vernier Acuity Cards, and Sloan Visual Acuity).
The mean contrast sensitivity function obtained using the CBI possessed the typical inverted u-shape, and CS scores correlated with those obtained with the FACT at 1.5, 6, 12, and 18 cycles per degree (p<0.05), but not at 3 cycles per degree (p=0.06). Similarly, the CBI yielded mean grating acuity and vernier acuity scores that correlated with those obtained using the TAC and the vernier acuity cards, respectively (all p<0.01). Note however, the CBI yielded CS scores and grating acuity scores 1.5 to 3 times higher than those obtained with its chart-based or card-based counterparts (all p<0.01).
Scores obtained with the CBI correlated with those obtained with chart-based and card-based tests implying that this new instrument may provide accurate measures of visual function in preschoolers. Also, the CBI offers important advantages over standard tests as it is relatively inexpensive, luminance levels can be precisely calibrated and controlled regardless of lighting conditions, and the software can store multiple tests with a near-infinite number of stimulus levels.
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