Ciliary Muscle Dimension Changes With Accommodation Vary in Myopia and Emmetropia

Kaphle, Dinesh; Schmid, Katrina L.; Davies, Leon N.; Suheimat, Marwan; Atchison, David A.

doi:10.1167/iovs.63.6.24

Cited by 16 publications

(15 citation statements)

References 40 publications

(65 reference statements)

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“…They found that during the process of accommodation, there was a pronounced thickening of the anterior muscle and a shortening of the curved nasal muscle length, notably more so in myopic eyes than in emmetropic ones. For consistent measurements within the same subject, they advocate the use of a fixed distance approach, while recommending a proportional distance methodology for cross-group refractive comparisons [ 14 ].…”

Section: Discussionmentioning

confidence: 99%

“…Another area of interest resides in the anatomy and biomechanics of the ciliary body, which governs lens shape. Specifically, myopic individuals exhibit a larger and stiffer ciliary muscle, potentially impacting accommodative function [ 14 ]. The concept of peripheral defocus, characterized by hyperopic defocus in the outer retinal regions, has emerged as a possible contributing element in myopia development [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

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Ciliary muscles contraction leads to axial length extension——The possible initiating factor for myopia

Meng,

Yang,

Zhou

2024

PLoS ONE

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Purpose This study aimed to investigate the underlying factors driving the onset of myopia, specifically the role of the ciliary muscle’s contraction in the elongation of the axial length of the eye. Methods The retrospective study was conducted utilizing data from three ophthalmic centers in Shanghai and Beijing. Both Chinese and Caucasian children were involved. The axial length of the subjects’ eyes was measured in both relaxed and contracted state of the ciliary muscle. A comprehensive mechanical model was also developed to observe the influence of ciliary muscle contraction on the axial length. Results This study included a sample of 198 right eyes of 198 myopic children. Of these, 97 were male and 101 were female, 126 were of Chinese ethnicity and 72 were Caucasian. The age of onset for myopia ranged from 5.9 to 16.9 years old. The axial length of the eye decreased 0.028 ± 0.007mm following dilation, indicating relaxation of the ciliary muscle (t paired student = 15.16, p = 6.72 x 10−35). In contrast, ciliary muscle contraction resulted in an increase in axial length. Considering proportionality, a significant 90.4% (179 eyes) exhibited a reduced axial length, while a minor 9.6% (19 eyes) demonstrated an increase post-mydriasis. Finite element modeling demonstrated that muscle contraction caused a tension force that transmits towards the posterior pole of the eye, causing it to extend posteriorly. Conclusion The contraction of the ciliary muscle leads to an extension of the axial length. This could potentially be the initiating factor for myopia.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ciliary muscles contraction leads to axial length extension——The possible initiating factor for myopia

Meng,

Yang,

Zhou

2024

PLoS ONE

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“…This study was part of a larger project where emmetropes and myopes underwent a series of tests over a few days. The following measurements were taken for both unaccommodated and accommodated states: autorefraction, aberrometry, 13 ciliary muscle dimensions, 14 peripheral choroidal thickness and peripheral eye length. Screening to check suitability was completed for all participants.…”

Section: Methodsmentioning

confidence: 99%

Central and peripheral choroidal thickness and eye length changes during accommodation

Kaphle

Schmid

Suheimat

et al. 2023

Ophthalmic Physiologic Optic

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Eye length increases during accommodation, both on-axis and in the periphery. The aim of this study was to determine whether the peripheral choroid thins with accommodation and to determine the relationship with eye length changes measured at the same location. Methods: Subjects included 53 young adults in good ocular and general health, with 19 emmetropes and 34 myopes. Measurements from the right eye were made for 0 D and 6 D accommodation stimuli for ±30° horizontal visual field/retinal locations in 10° steps. Valid eye length and choroidal thickness measurements were obtained for 37 and 47 participants, respectively, and both measures were taken for 31 participants. 2.5% phenylephrine was instilled to dilate the pupils. Participants turned their eyes, without head movement, to fixate targets and to make the target 'as clear as possible' during measurements. Correction was made for the influence of lens thickness changing at different peripheral angles. Choroidal thickness was measured with a spectral-domain-Optical Coherence Tomographer. For peripheral images, the internal cross target on the capture screen was moved from the centre to 17.25° nasal/temporal positions. Results: In accordance with previous literature, eye length increased with accommodation. The greatest change (mean ± SD) of 41 ± 17 μm occurred at the centre, with a mean change across the locations of 33 μm. There were no significant differences between emmetropes and myopes. Choroidal thickness decreased with accommodation, with changes being about two-thirds of those occurring for eye length. The greatest change of −30 ± 1 μm occurred at the centre, with a mean change of −21 μm. Greater choroidal thinning occurred for myopes than for emmetropes (23 ± 11 vs. 17 ± 8 μm, p = 0.02). Conclusions: With accommodation, eye length increased and the choroid thinned, at both central and peripheral positions. Choroidal thinning accounted for approximately 60% of the eye length increase across the horizontal ±30°.

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“…Speci cally, myopic individuals exhibit a larger and stiffer ciliary muscle, potentially impacting accommodative function. 12 The concept of peripheral defocus, characterized by hyperopic defocus in the outer retinal regions, has emerged as a possible contributing element in myopia development. 13 Nevertheless, the role of peripheral defocus as either a cause or consequence of myopia remains an ongoing debate.…”

Section: Introductionmentioning

confidence: 99%

Ciliary muscles contraction leads to axial length extension —— The possible initiating factor for myopia

Zhou,

Wang,

Fan

et al. 2023

Preprint

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This study aimed to investigate the underlying factors driving the onset of myopia, specifically the role of the ciliary muscle’s contraction in the elongation of the axial length of the eye. The retrospective study was conducted utilizing data from three ophthalmic centers in Shanghai and Beijing. Both Chinese and Caucasian children were involved. The axial length of the subjects’ eyes was measured in both relaxed and contracted state of the ciliary muscle. A comprehensive mechanical model was also developed to observe the influence of ciliary muscle contraction on the axial length. This study included a sample of 198 right eyes of 198 myopic children. Of these, 97 were male and 101 were female, 126 were of Chinese ethnicity and 72 were Caucasian. The age of onset for myopia ranged from 5.9 to 16.9 years old. The axial length of the eye decreased 0.028 ± 0.007mm following dilation, indicating relaxation of the ciliary muscle (t paired student = 15.16, p = 6.72 x 10− 35). In contrast, ciliary muscle contraction resulted in an increase in axial length. Considering proportionality, a significant 90.4% (179 eyes) exhibited a reduced axial length, while a minor 9.6% (19 eyes) demonstrated an increase post-mydriasis. Finite element modeling demonstrated that muscle contraction caused a tension force that transmits towards the posterior pole of the eye, causing it to extend posteriorly. The contraction of the ciliary muscle leads to an extension of the axial length. This could potentially be the initiating factor for myopia.

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Ciliary Muscle Dimension Changes With Accommodation Vary in Myopia and Emmetropia

Cited by 16 publications

References 40 publications

Ciliary muscles contraction leads to axial length extension——The possible initiating factor for myopia

Ciliary muscles contraction leads to axial length extension——The possible initiating factor for myopia

Central and peripheral choroidal thickness and eye length changes during accommodation

Ciliary muscles contraction leads to axial length extension —— The possible initiating factor for myopia

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