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M. P. Rowe, G. P. Lewis, S. K. Fisher, G. H. Jacobs; Effects of Retinal Detachment and Re-Attachment Surgery on the Ground Squirrel Retina as Measured With mfERG. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5227. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To develop an animal model to study the effects of retinal detachment and re-attachment on the human macula.
The heavily cone-dominated retina of the California ground squirrel (Spermophilus beecheyi) is a good model for the human macula. Rhegmatogenous detachments were produced in squirrels by injecting saline into the sub-retinal space. Retinas were re-attached one day later with pneumatic retinopexy. mfERG recordings were obtained prior to surgery, while the retina was detached, and again at several times after re-attachment. Recordings were made at multiple spatial scales with best resolution typically around 3 degrees of visual angle at the detachment site.
The first order kernel of the mfERG typically had two corneal negative troughs separated by a large positive peak. Depths of the two troughs relative to the intervening peak varied systematically across the retina in a superior to inferior gradient perpendicular to the orientation of the elongated optic nerve head. Retinal responses (defined as the difference between the peak and the mean depth of the two troughs) was maximal in the inferior retina at a distance from the optic nerve head quantitatively consistent with previously published data on the spatial variation of cone density in the ground squirrel eye. While the retinas were detached, responses were significantly suppressed in a circular area typically about 15 degrees in diameter. During recovery, this suppression was reduced both in depth and in area. Most of the recovery took place within the first three weeks, but an easily detectable area of reduced function remained even three months following re-attachment.
Injured areas of ground squirrel retina can be identified and followed with sufficient spatial resolution to determine the rate and extent of recovery. The present data serve as a background for comparison that will allow tests of the ability of therapeutic interventions to preserve retinal function and/or improve the extent of recovery.
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