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M. B. Vidinova, R. O. Beirne, R. S. Anderson, R. Williams; Scotopic Contrast Sensitivity and the Level of Retinal Straylight. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1552.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have reported that scotopic contrast sensitivity loss with age can be an indicator of changes in neural mechanisms. We wished to study the effect of induced wide-angle intraocular straylight on peripheral grating contrast sensitivity under scotopic conditions.
Six normal young observers (aged 20 to 30 years) were tested. The stimuli were grating patches presented on a 21" CRT at 8 deg eccentricity, nasal retina. The mean background luminance was 0.0047 cd/m2 (-0.33 log Scotopic Td). A set of three white opacity filters of increasing density was used to simulate the increased straylight and absorption in the ageing eye. The absorption and the angular dependence of the straylight induced by the filters (wide angle scatter) were consistent with published data for the human eye. The retinal straylight level without and with the diffusing filters was evaluated using a compensation comparison method with the C-Quant straylight meter (Oculus, Wetzlar, Germany). The contrast sensitivity function for detection was measured for each straylight level.
The baseline straylight level for all subjects was within the normal range for their age. With the filters, the straylight increased from levels typical for 50-60 years of age to levels typical of significant cataract. The contrast sensitivity at all spatial frequencies gradually decreased with the increasing straylight level and absorption caused by the filters. Contrast sensitivity was significantly reduced by 0.1 log units on average ( p < 0.01) at an 80 year-old straylight level and by 0.3 log units (p < 0.01) at simulated straylight levels typical of cataract. This reduction was not systematically dependent on the spatial frequency
The loss of scotopic contrast sensitivity with age may be partly due to the increased level of straylight arising from aging changes of the ocular media.
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