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Corneal electrodes useful for clinical electroretinography require topical anesthesia, interfere with vision, can abrade, and are not well accepted by most children and many adults. A low mass conductive thread, corneal (DTL) electrode is described and comparatively tested against the Burian-Allen electrode. The DTL electrode was found to have few of the(More)
Chronically implanted intraocular electrodes were used to stimulate visual cortical responses to current passage through the retina. Electrical current threshold for the light-adapted cat retina lies in the region of 30 to 100 X 10(-6) amps. for the conditions used. Dark adaptation caused a large threshold increase. Retinal excitability also decreased when(More)
Fifty-four patients with a unilateral pigmented choroidal lesion were studied with electrooculography (EOG). Eighteen of 21 patients with histologically proven (13) or presumed (8) malignant tumors of the choroid had light peak-dark trough ratios (L/D) ⩽ 150. Seventeen of 21 patients in the malignant group had an interocular L/D difference (L/Dd) ⩾ 23%,(More)
Hereditary blindness in Rhode Island Red chickens was analyzed at various post-hatching stages by light microscopy and electrophysiological recordings. At the time of hatching the retina of affected chicks appeared morphologically normal and identical to that of control, non-affected chicks. Whereas the electroretinographic (ERG) response to light stimulus(More)
A closed colony of semi-free-ranging rhesus monkeys maintained in isolation since 1938 by the Caribbean Primate Research Center (CPRC) is being studied as a model for age related macular drusen. Of examined colony animals 57.7% of the monkeys and 47.3% of their eyes have drusen. The prevalence and severity of drusen are linearly related to increasing age(More)
The visual acuities (i.e., visual thresholds for pattern detection) of four dogs under neuromuscular block were measured using visually evoked cortical potentials (VECP) and/or pattern-evoked retinal potentials (PERR). Stimuli were phase-reversing square-wave gratings with a mean luminance of 86 cd/m2 and 70% contrast. The mean of the VECP thresholds of two(More)
With the increasing use of the rat as an animal model for glaucoma and for the evaluation of neuroprotective treatments, there is a need for a sensitive test of retinal ganglion cell (RGC) function in this species. The aims of this study were to detect functional abnormalities of the inner retina in a rat model of high intraocular pressure (IOP) using the(More)
Spatial and temporal tuning were examined for both retinal and cortical signals using low contrast sinusoidol gratings. Maximum PERR and VECP responses occurred at the 4 Hz alternation rate and at 0.68 and 2.2 cpd, respectively. A 25% low spatial frequency attenuation (LSFA) was observed for the PERR. To test the possibility that prior inability to detect(More)
The distribution of human cone cells is well known and is frequently cited. The distribution of human ganglion cells is less well known and was published in a booklet which is less frequently cited in the eye literature. Selected published curves provided by these authors and Snellen acuity data were digitally encoded, transformed to linear vertical axes(More)