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Aubrey L. Doede, Maria Laura Gomez, Jay Chhablani, Dirk-Uwe Bartsch, Lingyun Cheng, William R. Freeman; Vision Testing Algorithms For Time-dependent Stimuli In Patients With Macular Pathology. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5448.
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Visual acuity and other vision measurements used in clinical settings do not reflect real-world visual tasks. We have tested the Vimetrics Central Vision Analyzer (CVA), which performs a timed test of Landolt C visual acuity under six mesopic and glare conditions designed to simulate time-dependent, real-world conditions. We noted, however, that in eyes with macular pathology, patients complained that the stimulus duration was too short to respond in the allotted time. The purpose of this study was to determine the best presentation time in normal eyes and in eyes with macular disease.
39 normal eyes from 21 patients (ages 19-65, 52% female) and 16 eyes from 13 patients (ages 68-89, 78% female) with macular disease had best refracted visual acuity measured using a standard ETDRS chart prior to CVA testing. Testing was performed twice in each eye in random order. The testing consisted of automated displays of a tumbled Landolt C that appeared for 300 or 900 ms on a calibrated monitor of standardized luminance. The "C" was displayed in three mesopic conditions of 99% contrast against 3 Cd/m² (M-1) followed by lower contrast panels of 64% and 43% contrast (M-2 and M-3). Glare (backlighting)conditions were simulated using 99%, 10%, and 8% contrast against a 78 Cd/m² background (G-1, G-2, and G-3). Statistical analysis compared acuities and the differences between the 300 and 900 ms stimulus tests.
In eyes without macular pathology, we found that there was no significant difference between acuity values in any test panel when comparing the 300 and 900 ms stimulus (p-value between 0.24 and 0.99). Likewise, there was no increase in testing time with either stimulus (p=0.24). In eyes with macular disease, visual acuity was measured significantly lower using the 300 ms stimulus as compared to the 900 ms stimulus (p-value between 0.03 and 0.05).
Longer (900 ms) stimulus duration using the CVA produces a better visual acuity measurement than short duration in eyes with macular disease and resulting in a negligible increase in total test duration (36 secs). We have previously shown that reproducibility of the CVA device is be high (concordance correlation between 0.82 and 0.90), allowing us to conclude that this automated vision testing device allows six-domain real-world simulation vision testing to be performed even in eyes with macular pathology.
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