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The Effect of Axial Length on Red and Blue Light-Evoked Pupil Responses in Children Depends on Season

Blumenthaler, Marielle
http://rave.ohiolink.edu/etdc/view?acc_num=osu1554032080466664

Abstract Details

2019, Master of Science, Ohio State University, Vision Science.
Purpose Previous research has shown that increased time spent outdoors is protective against myopia onset. The role of intrinsically photosensitive retinal ganglion cells (ipRGCs) in illuminance detection and dopamine release suggests that ipRGCs may play a role in this process. Prior studies demonstrated that changes in ipRGC-driven pupil responses to multiple red and blue stimuli differed as a function of refractive error between myopic and non-myopic adults. The purpose of this study was to evaluate whether this effect exists in children, and if so, if it varies based upon season. Methods Subjects were 50 children aged 8-17 years (average age 11.5 ± 2.7 years, 32 females) with spherical equivalent (SEQ) refractive error between +1.51 and -5.69 diopters (non-cycloplegic autorefraction). The IOLMaster was used to measure axial length. Subjects were exposed to three different protocols where full-field stimuli oscillated between colored light and dark at 0.1 Hz in the following order: 1) alternating red and blue, 2) red-only, and 3) blue-only. The RAPDx pupilometer measured pupil sizes during the stimulus protocols. Twenty-six of the subjects were tested during the summer months (June, July, and August), with the other twenty-four tested during the winter months (January, February, and March). The primary outcome measure was the average difference in normalized pupil size between blue and red stimulation. Results Pupils tended to become smaller during blue stimulation than during red stimulation. The difference in these pupil sizes varied significantly by the season in which testing occurred. During the summer months, the normalized pupil size difference between blue and red stimulation was greater than during the winter months (winter: 0.051 ± 0.006; summer: 0.089 ± 0.006; p < 0.001). The association between this pupil outcome and axial length was also modified by the season in which testing occurred. During the summer months, subjects with shorter axial lengths showed a greater difference in pupil size between blue and red stimulation than did subjects with longer axial lengths (slope = 0.019, p = 0.006). During the winter months, this association was not present (slope = -0.001, p = 0.90; axial length x season interaction p-value = 0.022). Additionally, although subjects with less myopic refractive error tended to have larger differences in pupil size between blue and red stimulation, this effect did not reach statistical significance in either season (refractive error x season interaction p-value = 0.98; slope = 0.006, p = 0.073). Conclusions During the summer months, subjects with shorter axial lengths experienced smaller pupils during blue stimulation and larger pupils during red stimulation. A potential explanation for this effect is increased summer light exposure causing more robust ipRGC-dependent pupil responses. These findings support the hypothesis that an adaptive ipRGC-driven dopaminergic pathway may exist where shorter eyes take advantage of greater light exposure to further inhibit the growth of the eye, reducing the risk of the onset of myopic refractive error.
Donald O Mutti, OD, PhD, FAAO (Advisor)
Andrew TE Hartwick, OD, PhD, FAAO (Committee Member)
Jeffrey J Walline, OD, PhD, FAAO (Committee Member)
89 p.
Ophthalmology; Optics
myopia, ipRGCs, dopamine, pupil

Recommended Citations

Citations

  • Blumenthaler, M. (2019). The Effect of Axial Length on Red and Blue Light-Evoked Pupil Responses in Children Depends on Season [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554032080466664

    APA Style (7th edition)

  • Blumenthaler, Marielle. The Effect of Axial Length on Red and Blue Light-Evoked Pupil Responses in Children Depends on Season. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1554032080466664.

    MLA Style (8th edition)

  • Blumenthaler, Marielle. "The Effect of Axial Length on Red and Blue Light-Evoked Pupil Responses in Children Depends on Season." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1554032080466664

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.