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Lei Shi, E E. Hartmann, Naser T. Naser, J W L. Lewis, Ying-Ling Chen, Ming Wang; Intraocular Scattering in Double-Pass Retinal Reflex. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3052.
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The accuracy, precision and breadth of ocular testing using double-pass photorefraction are affected by intraocular scattering. The purpose of this study is to evaluate and quantify the intraocular scatter in infrared double-pass photorefraction.
An infrared multi-eccentricity-meridian photoscreening method was used to acquire retinal reflex images in 45 optometry students and volunteers (13 males and 32 females) between 22 and 43 years of age. In this cohort, there were 8 African Americans, 3 Indians and 34 whites. Standard eye examinations were performed for all test subjects (90 eyes; Spherical equivalent ranged from +1 to -8.75 diopters). All eyes were healthy with no significant intraocular abnormities except for one subject (2 eyes) with congenital nuclear cataracts. The ocular scattering is determined from the pedestal-like signal in the retinal reflex image. A scattering factor was defined as the ratio of the scattering signal and the refraction signal. Correlations with age, race, and refractive error were analyzed.
As expected, the scatter factor was closely related to the spherical equivalent (SE). The amplitude of the scattering factor is larger for smaller SE and smaller for eyes with high refractive errors. Surprisingly, there was no significant relationship between the scatter factor and age or race in our sample. The scattering factors of the 2 eyes with nuclear cataracts were at the high end of the distribution curve.
The scatter factor in photorefraction shows potential for quantifying ocular scattering in individuals with a wide range of refractive errors. The scatter factor exhibited no significant dependence on the race of the subject. Also, no age sensitivity was detected, but this result is expected for the restricted age range of our observed cohort. Further studies on a larger sample size, wider age range, and inclusion of cataract patients are necessary to draw more general conclusions.
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