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The Effect of Refractive Error and Time Spent Outdoors on Red and Blue Light-Driven Pupil Responses

Morgan, Kelly M
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555351799339715

Abstract Details

2019, Master of Science, Ohio State University, Vision Science.
Purpose: Outdoor activity is one of several factors identified as risk factors for myopia development. The retina’s exposure to bright light may be one of the features of being outside that contributes to this protective effect. Specialized cells in the retina, ipRGCs, are thought to control this process. Since pupillary responses to blue light have been a useful measurement of ipRGC activity related to refractive error in past studies, and ipRGC activity may also contribute to slowing eye growth and myopia through their connection with amacrine cells and release of retinal dopamine, we are investigating the effects of bright light exposure on pupillary responses in order to better understand the protective nature of outdoor time on myopia development. Methods: Ten non-myopic subjects were each assigned to spend a large amount of time outdoors (target = 12 hours total) for 5 days and a small amount of time outdoors (target = 2 hours total) for 5 days with at least 5 days of separation between the experimental time periods. Pupillary responses to alternating blue and red light, followed by red light, then blue light as single colors were measured at the initial visit and following each 5 day period. Data were compared to data from a similar previous study with 10 myopic subjects. Results: Subjects spent an average (±SD) of 0.74 ± 0.24 more log lux-minutes outdoors in the high light exposure compared to the low light exposure week (p<0.0001). Single color blue testing resulted in greater dilation after the high light exposure week (normalized pupil size (±SD) = 0.70 ± 0.051) than the low light exposure week (0.74 ± 0.045; p = 0.011). Spherical equivalent was not correlated to any of the pupil outcomes and no other pupil outcome was significantly different between the two light exposure weeks. Many more pupil response outcomes were correlated with each other during the high (20 out of 21) than the low light exposure week (5 out of 21). When both myopic and non-myopic subjects were included in the analysis, pupil responses in both myopes and non-myopes were varied and overlapping when the difference in light exposure between weeks was small. When the difference in light exposure between weeks was large, the single color red minus alternating red pupil responses were more negative with increasing light exposure (p-value = 0.026 for the interaction between refractive error, light exposure difference between weeks, and the mono-alt red pupil outcome). Conclusions: Greater light exposure appeared to result in more inter-related pupil responses to red and blue light, regardless of refractive error. The expected changes in pupil responses to blue light as a function of light exposure and refractive error did not occur. However, myopes had a greater, more negative, difference in pupil responses to the single color minus alternating red stimulus than hyperopes when there was a greater difference in light exposure between weeks. One possible interpretation is that myopes had a less robust, or more transient, ipRGC-driven response during the exposure to red as a single color following the high light exposure week. Bright outdoor light would have suppressed pupil responses to red in myopes that are often seen in non-myopes. Inhibition of ipRGC activity with greater light exposure may underlie the lack of any beneficial effect of time outdoors on myopia progression.
Donald O. Mutti, O.D., PhD (Advisor)
Andrew T. E. Hartwick, O.D., PhD (Committee Member)
Jeffrey J. Walline, O.D., PhD (Committee Member)
84 p.
Environmental Health; Health; Health Care; Health Sciences; Ophthalmology; Optics
Myopia; ipRGC; outdoor light; light exposure; time spent outdoors; pupil responses; myopia control; myopia prevention

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Citations

  • Morgan, K. M. (2019). The Effect of Refractive Error and Time Spent Outdoors on Red and Blue Light-Driven Pupil Responses [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555351799339715

    APA Style (7th edition)

  • Morgan, Kelly. The Effect of Refractive Error and Time Spent Outdoors on Red and Blue Light-Driven Pupil Responses. 2019. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1555351799339715.

    MLA Style (8th edition)

  • Morgan, Kelly. "The Effect of Refractive Error and Time Spent Outdoors on Red and Blue Light-Driven Pupil Responses." Master's thesis, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555351799339715

    Chicago Manual of Style (17th edition)

osu1555351799339715
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