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George A. Zikos, Amitava Gupta, Rocco Robilotto, Ronald Blum, Arkady Selenow, Steven R. Ali; Wavefront and Pupil Dependence of Refractive Differences in Bright and Dim Environments. Invest. Ophthalmol. Vis. Sci. 2012;53(14):142.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the refractive differences in high and low illuminance environments
Visual acuity defocus curves were measured in 9 subjects under bright (1300Lux) and dim (0.3Lux) conditions using the CoViTS software using a reverse contrast tumbling E with crowding bars 4AFC staircase method. Pupil size was monitored during testing using an RK-726PCI ISCAN eye tracker. Wavefront aberration was measured using a COAS sensor in similar lighting conditions.
To evaluate the difference in refraction the difference in the defocus curve peaks was calculated. Three subjects exhibited myopic shifts (0.25 - 0.50D), four hyperopic (0.25 - 0.50D) and two had no shift. These differences exhibited a weak correlation (r^2=0.44) to LSA measured under dim conditions and the difference of the best fit sphere between the two conditions (r^2=0.34). Mean pupil difference during the defocus curve evaluation was 2.2 mm ±0.8 (1.3 - 3.6), similar to the difference measured during wavefront measurement 2.2 mm ±0.7 (1.2 - 3.3).
Patient’s refractions can differ significantly under different illumination conditions. This difference may be partially accounted for by subject’s spherical aberration.
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