June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Rod pathway electrical activity is modulated in the myopic mouse
Author Affiliations & Notes
  • Reece Mazade
    Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
    Atlanta VA Center for Visual & Neurocognitive Rehabilitation, Decatur, Georgia, United States
  • Machelle T Pardue
    Ophthalmology, Emory University School of Medicine, Atlanta, Georgia, United States
    Atlanta VA Center for Visual & Neurocognitive Rehabilitation, Decatur, Georgia, United States
  • Footnotes
    Commercial Relationships   Reece Mazade None; Machelle Pardue None
  • Footnotes
    Support  NIH R01 EY016435 (MTP), NIH R01 EY033361 (MTP), and Dept. of Veterans Affairs Research Career Scientist Award RX003134 (MTP)
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 843. doi:
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      Reece Mazade, Machelle T Pardue; Rod pathway electrical activity is modulated in the myopic mouse. Invest. Ophthalmol. Vis. Sci. 2023;64(8):843.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Bright ambient environments, which are signaled by retinal cone pathways, are strongly protective against myopia progression. Recently, dim conditions, which are signaled by rod pathways, were found to attenuate myopia in mice, and functional rod pathways are critical for myopia development. Yet, rod pathway signals have not been directly studied in myopic eyes. Here, we use a single-cell approach to investigate how rod pathway signaling is modulated in a mouse model of lens-induced myopia (LIM).

Methods : Myopia in C57BL/6J mice (males, P28) was generated by fixing a -10 diopter (D) lens over the right eye (OD) leaving the left eye (OS) free (n=12). A subset of mice was not treated with lenses (n=3). Refractive error was measured before lens placement and weekly for at least two weeks. After lens treatment, retinas were prepared for single-cell voltage clamp recordings. White, full-field, flash stimuli (0.003 – 300 cd/m2, 500 msec duration) were presented to dark-adapted rod bipolar cells (RBCs) identified via fluorescent labeling. Light-evoked inhibitory responses were compared between LIM (n=9 cells) and non-LIM (LIM OS + untreated, n=8 cells) eyes.

Results : After two weeks, LIM mice developed a myopic shift (OD – OS, -5.5±0.6 D, p<0.001, ANOVA) while untreated mice did not. We found that RBC response peak amplitude and latency (time-to-peak) were significantly modulated by lens treatment across flash intensity (interaction effects, peak amplitude: p=0.007, latency: p=0.022, ANOVAs). When responses were binned across flash intensities and compared to non-LIM responses, LIM response peak amplitudes were ~25% weaker with scotopic flashes (6.4±1.4 vs. 8.5±1.6 pA, p=0.32) but ~39% stronger with photopic flashes (15.7±2.3 vs. 11.3±2.1 pA, p=0.09), though they were not individually significant. Moreover, while response latency in LIM eyes was delayed across flash intensities, it was most pronounced with scotopic flashes (383±18 vs. 263±27 ms, p<0.001).

Conclusions : Our results provide direct electrophysiological evidence showing rod pathway signal strength and timing are altered in myopia. Interestingly, the direction of change was a function of stimulus intensity (reduced with scotopic stimuli but increased with photopic stimuli). Our preliminary findings suggest myopia affects rod pathway signal balance which may play a role in initiating or progressing myopic eye growth.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

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