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Researchers suggest multiple refraction measures for those with Down syndrome
Median refractive variability in a Down syndrome population as quantified with dioptric difference was 2.8 times the levels observed in controls, according to researchers.
The Down syndrome sample had a mean spherical equivalent of -0.04 D, and the control sample had a mean spherical equivalent of -1.32 D. Values were statistically significant, with the Down syndrome values shifted toward more hyperopic values, according to researchers.
More astigmatism was present in individuals with Down syndrome, with a mean magnitude of 0.99 D, versus controls at 0.34 D.
“Variability in refractive error was elevated in the Down syndrome sample, as compared to the control sample, and this variability was driven variability in the oblique astigmatism component,” researchers wrote.
Potential sources of variability in the objective refraction include poor fixation, inattention to the visual target and optical deficits in the cornea and lens, researchers wrote.
The dioptric difference in the right and left eyes was found to be more variable in the patients with Down syndrome compared to those without.
Increased variability may result in a larger dioptric space that must be considered during the subjective refraction process, researchers wrote.
“If the refractive search space is not reduced by the use of retinoscopy, the clinician may have to provide the subject with a greater number of comparisons, or potentially alter the dioptric step size utilized during refraction, to identify the best possible sphero-cylindrical correction for the subject,” researchers wrote.
Increased variability in objective refraction in Down syndrome may lead to increased uncertainty in spectacle prescriptions for this population, they concluded.
These findings highlight the importance of utilizing multiple methods to measure refraction and corroborate findings across techniques, researchers wrote. – by Abigail Sutton
Disclosures: The researchers reported no financial disclosures.