Ciliary muscle dimension changes with accommodation vary in myopia and emmetropia


Purpose: The purpose of this study was to determine whether accommodation-induced changes in ciliary muscle dimensions vary between emmetropes and myopes, and the effect of the image analysis method. Methods: Seventy adults aged 18 to 27 years consisted of 25 people with emmetropia (spherical equivalent refraction [SER] +0.21 ± 0.36 diopters [D]) and 45 people with myopia (-2.84 ± 1.72 D). There were 23 people with low myopia (>-3 D) and 22 people with moderate myopia (-3 to -6 D). Right eye ciliary muscles were imaged (Visante OCT; Carl Zeiss Meditec) at 0 D and 6 D demands. Measures included ciliary muscle length (CML), ciliary muscle curved length (CMLarc), maximum ciliary muscle thickness (CMTmax), CMT1, CMT2, and CMT3 (fixed distances 1-3 mm from the scleral spur), CM25, CM50, and CM75 (proportional distances 25%-75%). Linear mixed model analysis determined effects of refractive groups, race, and demand on dimensions. Significance was set at P < 0.05. Results: Myopic eyes had greater CML and CMLarc nasally than emmetropic eyes. Myopic eyes had thicker muscles than emmetropic eyes at nasal positions, except CM25 and CMT3, and at CM75 temporally. During accommodation and only nasally, CML reduced in emmetropic and myopic eyes, and CMLarc reduced in myopic eyes only. During accommodation, both nasally and temporally, muscles thickened anteriorly (CMT1 and CM25) and thinned posteriorly (CMT3 and CM75) except for temporal CM75. Moderate myopic eyes had greater temporal CMLarc than low myopic eyes, and the moderate myopes had thicker muscles both nasally and temporally using fixed and proportional distances. Conclusions: People with myopia had longer and thicker ciliary muscles than people with emmetropia. During accommodation, the anterior muscle thickened and the curved nasal muscle length shortened, more in myopic than in emmetropic eyes. The fixed distance method is recommended for repeat measures in the same individual. The proportional distance method is recommended for comparisons between refractive groups.

Publication DOI:
Divisions: College of Health & Life Sciences > School of Optometry > Optometry
College of Health & Life Sciences > School of Optometry > Optometry & Vision Science Research Group (OVSRG)
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
College of Health & Life Sciences
Additional Information: © 2022 The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License.
Uncontrolled Keywords: Myopia,Emmetropia,Accommodation,ciliary muscle,Optical Coherence Tomography,Muscle, Smooth,Ciliary Body/physiology,Tomography, Optical Coherence,Humans,Adult,Sensory Systems,Cellular and Molecular Neuroscience,Ophthalmology
Publication ISSN: 1552-5783
Last Modified: 17 Apr 2024 07:21
Date Deposited: 28 Jun 2022 11:45
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PURE Output Type: Article
Published Date: 2022-06-25
Accepted Date: 2022-05-31
Authors: Kaphle, Dinesh
Schmid, Katrina L.
Davies, Leon N. (ORCID Profile 0000-0002-1554-0566)
Suheimat, Marwan
Atchison, David A.



Version: Published Version

License: Creative Commons Attribution

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