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M. J. Perez Carrasco, A. R. Barrio, C. Palomo-Alvarez, M. C. Puell, Applied Vision Research Group; Photopic Visual Acuity Does Not Predict Visual Function Under Night Conditions. Invest. Ophthalmol. Vis. Sci. 2010;51(13):972.
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© ARVO (1962-2015); The Authors (2016-present)
Under night driving conditions, visual acuity is compromised and become worse with age and certain ocular pathologies. This study was performed to analyze the relation between high and low contrast visual acuity (VA) of healthy subjects assessed under photopic and mesopic luminance conditions.
The study population was a sample of 53 healthy subjects, aged from 24 to 49 years (age mean: 38.3 ± 7.2 years). The selected criteria were: Best-corrected VA of at least 0.9 decimal, refractive error not greater than ± 3.00 D sphere or ± 1.50 D cylinder and without ocular diseases. In the right eye with the best optical correction, VA (logMAR in steps of 0.02 log units) was measured using high-contrast (96%) and low-contrast (10%) logMAR Bailey-Lovie letter charts under photopic (80 cd/m2) and mesopic (0.1 to 0.2 cd/m2) luminance conditions.
Under photopic conditions, high-contrast VA mean was 0.02 ± 0.07 log units and low-contrast VA was 0.18 ± 0.11 log units. A significant correlation was found (Pearson’s correlation = 0.57; p< 0.000) between high and low-contrast photopic VA. Under mesopic conditions, high-contrast VA was 0.45 ± 0.14 log units and low-contrast VA was 0.84 ± 0.12 log units. Additionally, mesopic VA exhibited a significant correlation (Pearson’s correlation = 0.66; p< 0.000) between high and low-contrast charts. No significant relation was found between photopic and mesopic high-contrast VA or between photopic and mesopic low-contrast VA.
The results indicated that photopic and mesopic high-contrast VA might predict photopic and mesopic low-contrast VA, respectively. However, photopic VA does not predict sufficiently night vision. We highlight the need to measure mesopic VA to evaluate visual function during night driving specially in elder subjects.
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