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Heather A Anderson, Melissa D Bailey, Chiu-Yen Kao; Ciliary Muscle Thickness in Adults with Down Syndrome. Invest. Ophthalmol. Vis. Sci. 2019;60(9):4306. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to investigate the relationship between age and refractive error (RE) with ciliary muscle thickness (CMT) in adults with Down syndrome.
Thirty three adults with Down syndrome were recruited for imaging of the ciliary muscle with an anterior segment optical coherence tomographer. Images were collected on the right eye of each subject 45 minutes post-dilation with 1% tropicamide and 2.5% phenylephrine. Images were analyzed to calculate thickness at 1, 2, and 3 mm posterior to the scleral spur (CMT1, CMT2, CMT3). Maximum thickness (CMTMAX) and the apical thickness at 1mm posterior to the scleral spur (CMT1 – CMT2) were also calculated. Spherical equivalent RE was based upon a best clinical refraction that utilized both non-dilated and dilated refractive findings for its determination. Multivariate regression analysis was performed to evaluate the relationship between CMT and RE while controlling for subject age at three locations (CMT1, CMT2, CMT3), as well as for apical thickness at CMT1.
Good quality images were analyzed from 27 subjects (mean age = 29 ± 9 years) with mean RE of -1.16 ± 5.10 D (range = -15.75 to +5.13 D). Mean CMT decreased with more posterior position (CMT1: 805 ± 82µm; CMT2: 539 ± 131 µm; CMT3: 309 ± 99 µm). Mean CMTMAX was 870 ± 56µm and mean apical fiber thickness was 266 ± 88 µm at CMT1. Overall there was a significant linear correlation indicating thinning CMT with increasing age for CMT1 and CMT2 (p≤0.05) and a significant interaction between RE and age for CMT2 (p = 0.05), but no significant correlation between CMT and RE was found for either location. CMT3 was not associated with age, but had a significant negative correlation with RE (p = 0.01) indicating thicker muscle with increasing myopic RE. Apical thickness was not associated with age, but had a significant positive correlation with RE (p = 0.01) indicating thicker muscle with increasing hyperopic RE.
CMT measures in adults with Down syndrome were similar to those previously reported in typical adults without Down syndrome. Also similar to previous reports, CMT was negatively correlated with RE in the posterior region (thicker muscles with increasing myopic RE) and positively correlated with refractive error for the anteriorly located apical fibers (thicker muscles with increasing hyperopic RE).
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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