June 2020
Volume 61, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2020
Assessing the variation of photoreceptor reflectance in cone dominant species
Author Affiliations & Notes
  • Mina Gaffney
    Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Robert F. Cooper
    Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
    Biomedical Engineering, Marquette University, Milwaukee, Wisconsin, United States
  • Jenna Cava
    Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Hannah M Follett
    Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Alexander E Salmon
    Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Susan Freling
    Max Planck Florida Institute for Neuroscience, Jupiter, Florida, United States
  • Ching Tzu Yu
    Graduate School of Biomedical Science, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Dana K Merriman
    Department of Biology, University of Wisconsin Oshkosh, Milwaukee, Wisconsin, United States
  • David Fitzpatrick
    Max Planck Florida Institute for Neuroscience, Jupiter, Florida, United States
  • Joseph Carroll
    Ophthalmology and Visual Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
    Cell Biology, Neurobiology, & Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
  • Footnotes
    Commercial Relationships   Mina Gaffney, None; Robert Cooper, Translational Imaging Innovations (I), Translational Imaging Innovations (C), US Patent App 16/389,942 (P); Jenna Cava, None; Hannah Follett, None; Alexander Salmon, None; Susan Freling, None; Ching Tzu Yu, None; Dana Merriman, None; David Fitzpatrick, None; Joseph Carroll, AGTC (F), MeiraGTX (C), MeiraGTX (F), OptoVue (F), Translational Imaging Innovations (I)
  • Footnotes
    Support  U24EY029891, UL1TR001436, T32EY014537, FFB PPA-0641-0718-UCSF, ALCON Research Institute
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 4506. doi:
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    • Get Citation

      Mina Gaffney, Robert F. Cooper, Jenna Cava, Hannah M Follett, Alexander E Salmon, Susan Freling, Ching Tzu Yu, Dana K Merriman, David Fitzpatrick, Joseph Carroll; Assessing the variation of photoreceptor reflectance in cone dominant species. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4506.

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

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Abstract

Purpose : Spatial and temporal variability in individual photoreceptor reflectance has been observed in humans using adaptive optics ophthalmoscopy. Here we examined if there is similar variability in photoreceptor reflectance in two cone dominant animal models, the northern tree shrew (Tupaia belangeri), and the thirteen-lined ground squirrel (Ictidomys tridecemlineatus).

Methods : Under isoflurane anesthesia, confocal (30μm pinhole, 0.622 ADD) adaptive optics scanning light ophthalmoscope (AOSLO) images were acquired using 790nm light in two thirteen-lined ground squirrels (1M, 1F) and two northern tree shrews (1M, 1F). Videos were recorded at two retinal locations for each animal at six-minute intervals until five timepoints per location were acquired. Videos from each timepoint were processed as previously described to produce a single .tif image for each time point.1 These images were aligned using a SIFT algorithm, then averaged using ImageJ to produce an image for identifying cones for analysis. Cones were identified using custom software, from which the Voronoi domain for each cone was derived. An eroded Voronoi-based mask (excludes the outermost 2-pixel edge of the Voronoi domain) was used to calculate the reflectance of each cone at each timepoint. These values were normalized to the mean pixel intensity from each timepoint. The variance over time was measured for each cell, and those with a variance of less than 0.05 were considered to have stable reflectance. The spatial variation of the cone reflectance was found by taking the standard deviation of all the cone reflectance values at a given timepoint.

Results : A total of 1,440 and 2,395 cones were analyzed for the northern tree shrews and thirteen-lined ground squirrels, respectively. There was spatial variation in cone reflectance in both species: the standard deviation was 59% of the mean cone reflectance for the northern tree shrew, and 47% of the mean for the thirteen-lined ground squirrel. In addition, 36% of the analyzed northern tree shrew cones showed temporal variance, compared to 32% for the thirteen-lined ground squirrel.

Conclusions : Despite substantial anatomical differences between cone photoreceptors in these species and humans, they display similar spatial and temporal variability in reflectance when imaged using confocal AOSLO. These data can help constrain models describing the cellular origins of such reflectance signals.

1PMID: 28392976

This is a 2020 ARVO Annual Meeting abstract.

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