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Effects of Light Scatter and Blur on Low-Contrast Vision and Disk Halo Size

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Puell Marín, María Cinta and Palomo Álvarez, Catalina (2017) Effects of Light Scatter and Blur on Low-Contrast Vision and Disk Halo Size. Optometry and Vision Science, 94 (4). pp. 505-510. ISSN 1040-5488

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Official URL: https://doi.org/10.1097/OPX.0000000000001061




Abstract

Purpose: To investigate the individual effects of forward light scatter (FLS) and refractive blur on low-contrast vision and the size of the disk halo produced in response to an external glare source.
Methods: Monocular disk halo radius, high- and low-contrast distance visual acuity (HCVA, LCVA), and contrast sensitivity (CS) were determined in 25 eyes of 25 healthy subjects under normal, FLS, and blur conditions. FLS was induced using the filter Black ProMist 2 to simulate an early cataract. Blur was induced using a +1.00 diopter lens to simulate an uncorrected refractive error.
Results: Similar significant mean increases in halo radius were observed for the FLS (0.32 ± 0.10 log arc min; P < .0001) and refractive blur (0.40 ± 0.18 log arc min; P < .0001). Under induced blur, 3 lines of HCVA (0.32 ± 0.15 logMAR; P < .0001) and 4 lines of LCVA (0.39 ± 0.16 logMAR; P < .0001) were lost. FLS had a minimal (but significant) effect on HCVA, but worsened mean LCVA by more than 1 line (0.13 ± 0.10 logMAR; P < .0001). Similar significant mean CS reductions of 0.17 ± 0.12 (P < .0001) and 0.14 ± 0.12 log units (P < .0001) were produced in response to FLS and refractive blur, respectively (approximately 1 triplet).
Conclusions: Forward light scatter and refractive blur contributed to an increased size of the disk halo produced by a glare source in similar proportion. Although defocus blur has a substantial effect on LCVA, a loss of more than 1 line of LCVA after best refractive correction would be indicative of FLS.


Item Type:Article
Additional Information:

Received June 3, 2016; accepted November 22, 2016.

Uncontrolled Keywords:Forward light scatter, Disk halo, Straylight, Refractive blur, Visual acuity, Contrast sensitivity, Early cataract
Subjects:Medical sciences > Medicine > Ophtalmology
Medical sciences > Optics > Low vision
Medical sciences > Optics > Optometry
ID Code:44383
Deposited On:31 Aug 2017 07:23
Last Modified:31 Aug 2017 07:23

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