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Ciliary Muscle and Sustained Accommodation

Ransdell, Amanda, OD
http://rave.ohiolink.edu/etdc/view?acc_num=osu1427279533

Abstract Details

2015, Master of Science, Ohio State University, Vision Science.
Purpose: to determine how the dimensions of the ciliary muscle are related to a subject’s ability to sustain accommodation by measuring accommodative lag and accommodative fatigue in school-age children and pre-presbyopic adults. Methods: 117 subjects ages five to thirty years participated in the present study. Images of the nasal ciliary muscle of the relaxed right eye were obtained with the Zeiss Visante Anterior Segment Optical Coherence Tomographer. Autorefraction measurements of the right eye were performed at distance and near using the Grand Seiko Autorefractor, with habitual correction worn at near so the accommodative response, not refractive error, was found. Amplitude of accommodation was measured three times and averaged. Subjects were then asked to watch a 2 minute video at 40 centimeters while keeping vision clear out of alternating +2.50 diopter (D) and -2.50 D lenses over any habitual correction. Autorefraction at near was repeated after the accommodative fatigue task. Ciliary muscle images were analyzed and thickness was measured at multiple points along the length of the muscle, including the point of maximum thickness (CMTMAX) and at 1 mm (CMT1), 2 mm (CMT2), and 3 mm (CMT3) posterior to the scleral spur. The thickness of the ciliary muscle at the apex was also calculated (CMTMAXApical and CMT1Apical). Accommodative lag was calculated for all subjects before and after the fatigue task using the subject’s accommodative response and refractive error. Stepwise linear regression procedures were used to model the relationship between all accommodative measurements and each ciliary muscle thickness measurement (CMTMAX, CMT1, CMT2, CMT3, CMTMAXApical, and CMT1Apical) and paired t-tests were performed to demonstrate the change in accommodative lag before and after the fatigue task. Results: Only age was significantly associated with the mean amplitude of accommodation for the analyses of all subjects, children, and adults. Although not statistically significantly, CMTMAX was found to be thinner in subjects with average amplitudes of accommodation below the age-expected average. Similar results were found for CMT2, and CMT3. When average amplitudes of accommodation were below the minimum based on age, CMT2 and CMT3 were found to be thinner, but the difference was not quite statistically significant. When accommodative lag was measured prior to the accommodative fatigue task, younger age was significantly associated with a larger accommodative lag for all models of ciliary muscle thickness. The more anterior regions of the muscle were significantly associated with refractive error. For the models including predictors for the apical region of the ciliary muscle, there was also a significant interaction between ciliary muscle thickness and refractive error, where more hyperopic refractive errors with thinner apical ciliary muscle thickness were associated with greater accommodative lag. For models including predictors for the posterior region of the muscle, the trend was the opposite, where more myopic refractive errors with thicker ciliary muscles were associated with greater accommodative lag. The results were similar when accommodative lag was measured after the accommodative fatigue task. Some subjects may have been in an accommodative spasm post-fatigue task because their post-fatigue task accommodative lag was lower than their measured pre-fatigue task accommodative lag. The trend was for these subjects to have a thinner ciliary muscle than subjects whose accommodative lag was more positive post-fatigue task compared with pre-fatigue task, but the differences were not statistically significant. Conclusions: Only age was significantly associated with the mean amplitude of accommodation for the analyses of all subjects, children, and adults. The more apical and posterior regions of the ciliary muscle and refractive error were associated with accommodative lag prior to and after an accommodative fatigue task.
Melissa Bailey, OD, PhD (Advisor)
Marjean Kulp, OD, PhD (Committee Member)
Donald Mutti, OD, PhD (Committee Member)
53 p.
Ophthalmology
ciliary muscle; sustained accommodation; accommodative fatigue

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Citations

  • Ransdell, OD, A. (2015). Ciliary Muscle and Sustained Accommodation [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1427279533

    APA Style (7th edition)

  • Ransdell, OD, Amanda. Ciliary Muscle and Sustained Accommodation. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1427279533.

    MLA Style (8th edition)

  • Ransdell, OD, Amanda. "Ciliary Muscle and Sustained Accommodation." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1427279533

    Chicago Manual of Style (17th edition)

osu1427279533
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