Influence of chromatic light on lens-induced myopia in mice Restricted; Files Only

Strickland, Ryan (Spring 2018)

Permanent URL: https://etd.library.emory.edu/concern/etds/hd76s011c?locale=en
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Abstract

Importance: Across multiple populations, the prevalence of myopia, or nearsightedness, has increased in recent decades. In addition to the high cost of treatment, pathological myopia increases the risk of blindness. Therefore, investigations into how environmental factors, such as light, influence the development of myopia are essential.

 

Purpose: White light contains several wavelengths that are focused at different focal planes within the eye, referred to as longitudinal chromatic aberrations (LCA). To characterize the effect of LCA on refractive development, wild-type C57BL/6J mice were placed in monochromatic light both with and without hyperopic lens defocus. To determine the role of cone photoreceptors in LCA, mice with abnormal cone function were housed under monochromatic light.

 

Methods: Wild-type C57BL/6J and cone dysfunction ALS/LtJ/Gnat2cpfl3 mice were housed in one of three LED lighting conditions beginning at post-natal day 28 (P28): white (425-700 nm), green (525 nm), or violet (400 nm) light. A subset of C57BL/6J mice received a head-mounted -10 diopter (D) lens over the right eye at P28. Refractive error, corneal curvature, and ocular axial parameters were measured weekly until P56 using photorefraction, keratometry, and spectral-domain optical coherence tomography (SD-OCT), respectively.

 

Results: By P42, C57BL/6J mice exposed to violet light became significantly more hyperopic than mice exposed to white or green light. Lens-treated C57BL/6J mice exposed to violet light demonstrated a significantly smaller myopic shift than lens-treated mice exposed to white or green light at P56. The difference in refractive error can be attributed to a significantly elongated vitreous chamber in mice exposed to white light compared to violet light. ALS/LtJ/Gnat2cpfl3 mice exposed to violet, green or white light did not demonstrate any significant differences in refractive error or ocular axial parameters by P56.

 

Conclusions: Mice can be used as an effective model to study chromatic influence on refractive development. Mice respond to monochromatic light in a way that could be predicted by LCA, and the effect of lens defocus was altered depending on light exposure. Cones are likely responsible for the hyperopic refractive changes in response to violet light, as mice with cone dysfunction eliminated this effect.  

Table of Contents

Introduction………………………………………………………………………………………………………….…1

Methods…………………………………………………………………………………………………………………5

Results……………………………………………………………………………………………………………………9

Discussion……………………………………………………………………………………………………………..13

Tables & Figures……………………………………………………………………….…………………………….19

             Table 1: Animals in Experimental Groups…………………………………………………………..19

             Figure 1: Light Wavelength Data………………………………………………………………………20

             Figure 2: Overview of Study and Methods…………………………………………….……………21            

             Figure 3: C57BL/6J Refraction Data…………………………………………………………..………23

             Figure 4: C57BL/6J Ocular Parameters…………………………………………………….…………25

             Figure 5: ALS/LtJ/Gnat2cpfl3 Refraction Data……………………………………………..…………27

             Figure 6: ALS/LtJ/Gnat2cpfl3 Ocular Parameters……………………………………………………28

References………………………………………………………………………………….…………………………29

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