June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Mild but not moderate intraocular pressure increase compromises the ability of mouse retinal ganglion cells to adapt to light level
Author Affiliations & Notes
  • Xiaofeng Tao
    Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
  • Jasdeep Sabharwal
    Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
  • Samuel M Wu
    Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
  • Benjamin J Frankfort
    Ophthalmology, Baylor College of Medicine, Houston, Texas, United States
  • Footnotes
    Commercial Relationships   Xiaofeng Tao, None; Jasdeep Sabharwal, None; Samuel Wu, None; Benjamin Frankfort, None
  • Footnotes
    Support  NIH Grant EY025601, NIH Grant EY002520, and unrestricted grant from Research to Prevent Blindness
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 3863. doi:
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    • Get Citation

      Xiaofeng Tao, Jasdeep Sabharwal, Samuel M Wu, Benjamin J Frankfort; Mild but not moderate intraocular pressure increase compromises the ability of mouse retinal ganglion cells to adapt to light level. Invest. Ophthalmol. Vis. Sci. 2020;61(7):3863.

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

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Abstract

Purpose : The ability to adapt to ambient light levels is an important aspect of retinal function. This ability has been demonstrated in retinal ganglion cells (RGCs), which show dynamic changes in the spatiotemporal characteristics of their receptive fields (RFs) depending on light level. Here, we present our findings on the capacity of mouse RGCs to adapt to light intensity changes, and how this is affected by IOP elevation with an inducible glaucoma model.

Methods : IOP elevation was achieved in 12-week old wild type C57BL6J mice of both genders by injecting microbeads into the anterior chamber in one eye. Uninjected eyes or saline injected eyes served as controls. Retinas were collected two weeks after injection and mounted on a 60-electrode multielectrode array (MEA) for electrophysiology. The identification of RGCs and characterization of their RFs occurred according to a previously reported protocol (Tao, et al., 2019). Spatial and temporal RF characteristics under scotopic and photopic lighting, and the changes in these RF characteristics according to light level were compared between uninjected eyes, saline injected eyes, and microbead injected eyes across two levels of IOP elevation.

Results : Average IOPs in uninjected eyes and saline injected eyes were similar. Microbead injection resulted in Mild (~2mmHg) or Moderate (~5mmHg) increases in average IOP. 1373 RGCs were included in the study, and 454 RGCs had identifiable scotopic spike-triggered averages (STAs) and were subjected to the analysis of scotopic physiology and light adaptation behavior. Scotopic STAs were most likely to occur in RGCs exposed to Mild IOP increase (~47%). For all groups, center RF size remained about the same under scotopic and photopic lighting and both center and surround STA peak times increased under scotopic conditions. Mild, but not Moderate IOP elevation caused a higher spontaneous firing rate as well as attenuated light-induced changes in relative surround RF strength and center STA peak time.

Conclusions : RGCs have a remarkable ability to adapt to reduced light input. When stressed by mild, but not moderate IOP increases, RGCs showed increased excitability and reduced capacity to adapt to light level. This suggests that smaller IOP increases may involve different pathologic mechanisms than those found after larger IOP increases.

This is a 2020 ARVO Annual Meeting abstract.

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