Eye model for the ground squirrel

Sussman, Dafna; Chou, B. Ralph; Lakshminarayanan, Vasudevan

doi:10.1080/09500340.2010.548608

Cited by 4 publications

(5 citation statements)

References 15 publications

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“…The horizontal optic nerve head (ONH) lies approximately where “retina” is indicated. Reproduced from Chou & Cullen ( 1984 ) and Sussman et al ( 2011 ) with permission. Schematic of photoreceptor density in relation to the horizontal ONH (dark black line) of the California ground squirrel ( B ).…”

Section: Introductionmentioning

confidence: 99%

“…The 13-lined ground squirrel (13LGS) possesses a small lens relative to its eye size ( Fig. 1A ; Chou & Cullen, 1984 ; Sussman et al, 2011 ), similar to the human eye. We believe that this is beneficial for AO retinal imaging, as the optical surfaces that are likely the source of the eye’s monochromatic aberration are close to the exit pupil plane, and thus more amenable to correction with a single wavefront corrector that is optically conjugate to it.…”

Section: Introductionmentioning

confidence: 99%

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Noninvasive imaging of the thirteen-lined ground squirrel photoreceptor mosaic

et al. 2016

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Ground squirrels are an increasingly important model for studying visual processing, retinal circuitry, and cone photoreceptor function. Here, we demonstrate that the photoreceptor mosaic can be longitudinally imaged noninvasively in the 13-lined ground squirrel (Ictidomys tridecemlineatus) using confocal and nonconfocal split-detection adaptive optics scanning ophthalmoscopy using 790 nm light. Photoreceptor density, spacing, and Voronoi analysis are consistent with that of the human cone mosaic. The high imaging success rate and consistent image quality in this study reinforce the ground squirrel as a practical model to aid drug discovery and testing through longitudinal imaging on the cellular scale.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Noninvasive imaging of the thirteen-lined ground squirrel photoreceptor mosaic

et al. 2016

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“…26 A working distance of at least 50 mm is desirable when imaging the 13-LGS and other species to avoid positioning interference with the rotational stage and anesthesia equipment. 27 With these hardware parameters, we calculate a theoretical diffraction-limited lateral resolution of ∼2.0 μm in the 13-LGS eye [28][29][30][31] (Appendix), although ocular aberrations are uncorrected, so this is certainly an overestimate, and current eye models for the 13-LGS are not as well developed as for humans and mice. Optical power at the cornea was measured to be 0.05 to 3.25 mW depending on the ND filter wheel position using a power meter (1931-C; Newport Corporation, Irvine, CA) set to the center wavelength; the maximum power was used for all images included in this study, as this was calculated to be safe for all scan protocols used (Appendix).…”

Section: Methods Custom High-speed Oct-a System Hardwarementioning

confidence: 99%

Optical Coherence Tomography Angiography in the Thirteen-Lined Ground Squirrel

Salmon

Chen

Atry

et al. 2021

Trans. Vis. Sci. Tech.

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To assess the performance of two spectral-domain optical coherence tomography-angiography systems in a natural model of hypoperfusion: the hibernating thirteen-lined ground squirrel (13-LGS).Methods: Using a high-speed (130 kHz) OCT-A system (HS-OCT-A) and a commercial OCT (36 kHz; Bioptigen Envisu; BE-OCT-A), we imaged the 13-LGS retina throughout its hibernation cycle. Custom software was used to extract the superior, middle, and deep capillary plexus (SCP, MCP, and DCP, respectively). The retinal vasculature was also imaged with adaptive optics scanning light ophthalmoscopy (AOSLO) during torpor to visualize individual blood cells. Finally, correlative histology with immunolabeled or DiIstained vasculature was performed.Results: During euthermia, vessel density was similar between devices for the SCP and MCP (P = 0.88, 0.72, respectively), with a small difference in the DCP (−1.63 ± 1.54%, P = 0.036). Apparent capillary dropout was observed during torpor, but recovered after forced arousal, and this effect was exaggerated in high-speed OCT-A imaging. Based on cell flux measurements with AOSLO, increasing OCT-A scan duration by ∼1000× would avoid the apparent capillary dropout artifact. High correspondence between OCT-A (during euthermia) and histology enabled lateral scale calibration. Conclusions:While the HS-OCT-A system provides a more efficient workflow, the shorter interscan interval may render it more susceptible to the apparent capillary dropout artifact. Disambiguation between capillary dropout and transient ischemia can have important implications in the management of retinal disease and warrants additional diagnostics.Translational Relevance: The 13-LGS provides a natural model of hypoperfusion that may prove valuable in modeling the utility of OCT-A in human pathologies associated with altered blood flow.

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“…The entire sclera is darkly pigmented. Their emmetropic eyes are thought to have low spherical and chromatic aberration (Sussman et al, 2011; Gur & Sivak, 1979). The GS lens is spherical, yellow, and small relative to the size of the globe (Vaidya 1965), which facilitates intraocular manipulations of the retina.…”

Section: Ground Squirrel Visual Systemmentioning

confidence: 99%

Seasonal and post-trauma remodeling in cone-dominant ground squirrel retina

Merriman

Sajdak

et al. 2016

Experimental Eye Research

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With a photoreceptor mosaic containing ~85% cones, the ground squirrel is one of the richest known mammalian sources of these important retinal cells. It also has a visual ecology much like the human’s. While the ground squirrel retina is understandably prominent in the cone biochemistry, physiology, and circuitry literature, far less is known about the remodeling potential of its retinal pigment epithelium, neurons, macroglia, or microglia. This review aims to summarize the data from ground squirrel retina to this point in time, and to relate them to data from other brain areas where appropriate. We begin with a survey of the ground squirrel visual system, making comparisons with traditional rodent models and with human. Because this animal’s status as a hibernator often goes unnoticed in the vision literature, we then present a brief primer on hibernation biology. Next we review what is known about ground squirrel retinal remodeling concurrent with deep torpor and with rapid recovery upon re-warming. Notable here is rapidly-reversible, temperature-dependent structural plasticity of cone ribbon synapses, as well as pre- and post-synaptic plasticity throughout diverse brain regions. It is not yet clear if retinal cell types other than cones engage in torpor-associated synaptic remodeling. We end with the small but intriguing literature on the ground squirrel retina’s remodeling responses to insult by retinal detachment. Notable for widespread loss of (cone) photoreceptors, there is surprisingly little remodeling of the RPE or Müller cells. Microglial activation appears minimal, and remodeling of surviving second- and third-order neurons seems absent, but both require further study. In contrast, traumatic brain injury in the ground squirrel elicits typical macroglial and microglial responses. Overall, the data to date strongly suggest a heretofore unrecognized, natural checkpoint between retinal deafferentiation and RPE and Müller cell remodeling events. As we continue to discover them, the unique ways by which ground squirrel retina responds to hibernation or injury may be adaptable to therapeutic use.

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Eye model for the ground squirrel

Cited by 4 publications

References 15 publications

Noninvasive imaging of the thirteen-lined ground squirrel photoreceptor mosaic

Noninvasive imaging of the thirteen-lined ground squirrel photoreceptor mosaic

Optical Coherence Tomography Angiography in the Thirteen-Lined Ground Squirrel

Seasonal and post-trauma remodeling in cone-dominant ground squirrel retina

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