PubMed · 726321
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
T W White, S A Kelly, J F Sturr. 1978. Large field early light adaptation.. https://doi.org/10.1016/0042-6989(78)90261-4
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Explore the source record for details and available documents.
GABA is a likely feedback transmitter from H1 horizontal cells to cone photoreceptors in fish retinas. Spinules arise from H1 cell dendrites in light-adapted retinas, are correlated with responses attributed to feedback, and have been proposed to be the GABA release sites. We used mAb 62-3G1, an antibody against the beta 2/beta 3 subunits of the GABAA receptor complex, to visualize GABAA receptor immunoreactivity (GABAr-IR) in photoreceptors as a function of light and dark adaptation at the electron microscopical level. Regardless of adaptation, GABAr-IR was restricted to the synaptic terminals of all cones and most rods; synaptic vesicular membrane and plasma membrane, exhibited GABAr-IR. Contrary to expectations, the density of GABAr-IR was least on the plasma membrane within the invagination, regardless of the presence or absence of spinules. Dense GABAr-IR was observed on the lateral surface of cone pedicles, on cone processes proximal to the invagination, and on presumed telodendria from nearby cones. There was no difference in GABAr-IR of rod plasma membranes within or outside of the invagination or with adaptation. The only novel effect of adaptation was in regards to the density of synaptic vesicles. Cones showed a 29% increase in vesicle density with dark adaptation, whereas rods showed a 17% decrease. We conclude that all goldfish photoreceptors will be GABA-sensitive and that the sensitivity is distributed over the surface of the synaptic terminal rather than localized to within the invagination. The role of spinules in GABA release remains to be determined, but we conclude that spinules are not related to the GABA sensitivity of goldfish photoreceptors.
PURPOSE: To document the functional outcome of two patients following successful macular translocation for the treatment of severe subretinal hemorrhage in age-related maculopathy. METHODS: The retina was surgically rotated around the optic nerve with translocation of the fovea either upward or downward to an area of healthy retinal pigment epithelium. In the postoperative period, visual function was carefully studied with emphasis on adaptation to torsion. RESULTS: Visual acuity in one patient improved from 20/200 to 20/80 and the other patient remained at 20/200. Both patients developed horizontal and vertical strabismus with torsion of up to 55 degrees. After a prolonged period of occlusion of the unoperated eye, both patients were subjectively able to adapt to monocular torsion. However, adaptation under binocular conditions did not occur. CONCLUSION: Macular translocation was successful in improving visual acuity in one patient, with no improvement in the second. Both patients had significant ocular torsion and strabismus, but under monocular conditions they were successful in perceptually adapting to the change in the visual environment. Fear of cyclotorsion should not be a deterrent to considering macular translocation as a possible treatment option for severe subretinal macular hemorrhage if the patient is willing to accept monocular vision.