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W. Gutstein, S. H. Sinclair, R. V. North; Vision Measurement Under Conditions of Luminance and Contrast That Simulate Real World Environments. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3212.
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© ARVO (1962-2015); The Authors (2016-present)
Clinicians currently must utilize several devices to measure alterations of vision: 1)resolution 2)luminance adaptation 3)contrast 4)color and 5)off-axis "veiling" glare. Furthermore, vision measurement should remove the bias of the examiner and measure the vision under conditions that simulate activities of daily living. This report compares the results of vision measurement of normal individuals under such conditions using the Central Vision Analyzer (CVA) with vision measured utilizing acuity charts under similar lighting and contrast conditions.
The VA of 162 emmetropic, normal eyes (refractive errors -0.50D to +0.75D spherical equivalence, astigmatism < 0.50D) of 81 healthy persons between the ages of 18 and 65 were measured with both the CVA and with ETDRS charts. The CVA, an interactive computer program, presents a 250 msec Landolt C, tumbled in 1 of 4 positions and thresholds for the smallest C correctly discriminated (threshold 2 correct answers at the lowest optotype size, with 2 incorrect answers at the next step lower utilizing logMAR 0.05 steps). In sequential fashion, the CVA tests 3 mesopic environments (99%, 50% and 25% Michelson Contrast, MC) and 3 glare environments (99%, 10% and 8% MC). The VA was also tested with logMAR 0.1 letter charts (ETDRS) of the same contrast letters and background luminance. VA with the charts was scored by both line assignment (3 of 5 letters) and total letter count. Pearson correlation coefficients and Bland & Altman differences were calculated to examine similarity.
All CVA modules demonstrated excellent Pearson correlation and Bland and Altman similarity with the acuity charts examined under the same conditions (r=.862 to r=.984,p<.001). In addition, when the 15% contrast chart is viewed with the sun at 150 off-axis a similar VA is obtained as with the 8% CVA contrast chart viewed with the sun overhead.
The CVA represents a method that, independent of the examiner, thresholds accurately the VA of normal individuals compared with charts under conditions of contrast and luminance that simulate activities of daily living.
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