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M. C. Puell Marin, M. J. Perez-Carrasco, C. Palomo-Alvarez, A. R. Barrio; Relationship Between Mesopic Visual Function and Intraocular Light Scatter. Invest. Ophthalmol. Vis. Sci. 2010;51(13):974.
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© ARVO (1962-2015); The Authors (2016-present)
Forward light scatter in the eye can reduce retinal image contrast especially under low luminance conditions and with age. Although it has been found a weak relation between intraocular light scatter (IOLS) and photopic high-contrast visual acuity (VA), the extent to which the IOLS affects mesopic VA remains unknown. This study was performed to analyze whether the variability in high (HC) and low (LC) -contrast VA at mesopic light level is attributable to differences in IOLS.
Measurements were obtained in the better eye of 191 healthy subjects without cataracts. Two groups were defined: 106 subjects (age < 55 years) and 85 subjects (age ≥ 55 years). Visual acuity (logMAR in steps of 0.02 log units) was measured with the best spectacle correction using high-contrast (96%) and low-contrast (10%) logMAR letter charts under mesopic luminance conditions (0.1 to 0.2 cd/m2). Scattered light on the retina was measured using the C-Quant straylight meter (Oculus AG, Germany) according to the psychophysical compensation comparison method. Values are expressed as logs (of the straylight parameter) for which higher values indicate more scattered light and more sensitivity to glare.
In the group below 55 years of age, mean mesopic HC-VA was 0.39 ± 0.13 and LC-VA was 0.74 ± 0.15 log units. Mean IOLS was 0.96 ± 0.14 log units. With the regression analysis of linear model, we found a significant correlation between HC-VA and IOLS (r =0.37; p < 0.01) and between LC-VA and IOLS (r =0.43; p < 0.01). Below 55 years of age, mesopic VA was significantly worse for subjects with higher IOLS. In the group above 55 years of age, mean mesopic HC-VA was 0.46 ± 0.09 and LC-VA was 0.74 ± 0.12 log units. Mean IOLS was 1.20 ± 0.19 log units. In this group, there were not any significant relationship between HC-VA and IOLS or between LC-VA and IOLS.
Below 55 years of age, inter-subject differences in IOLS showed correlation with mesopic HC-VA and LC-VA. Subjects with lower IOLS and therefore better retinal image quality reached higher mesopic VA values. Above 55 years of age, the ageing eye revealed more IOLS without correlation with mesopic VA.
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