Insight into blindness

Article Abstract:

The retina is the surface at the back of the eye which receives light and images; its health is critical to vision and retinal degeneration is a major cause of blindness. Retinitis pigmentosa (RP) is a disease in which photoreceptors and other cells in the retina degenerate. As the disease progresses, pigmented spicules (tiny bumps) are deposited across the surface of the retina. RP is clearly a genetic disease, but in some families it has an autosomal dominant pattern of inheritance, while in others it has an autosomal recessive or an X-linked pattern. Since the disease is relatively common, occurring in about one in 4,000 people worldwide, there are ample opportunities for studying families with the gene. Peter Humphries and colleagues were able to map the gene to the q region (long arm) of chromosome 3 in an Irish family with autosomal dominant retinitis pigmentosa (ADRP) pedigree. T.P. Dryja and coworkers, knowing that the opsin gene maps onto 3q, rapidly identified a defect in this gene in ADRP patients. Dryja et al. report their findings in the January 25, 1990 issue of Nature. One specific form of ADRP can now be diagnosed, and it seems likely that this knowledge will soon point towards the molecular basis for other related forms of retinal degeneration. Couples planning to have children who have a family history of ADRP can now obtain accurate genetic screening and counselling. (Consumer Summary produced by Reliance Medical Information, Inc.)

Genetic aspects, Retinal diseases, Genetic disorders, Retinitis pigmentosa

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Blindsight in normal observers

Article Abstract:

The ability to distinguish visual stimuli in people who have lesions in their visual cortex, referred as blindsight can be stimulated in normal people by two different visual displays. A contrast between visual textures is initially introduced followed by complementary textures involving opposite motion or binocular rivalry and orthogonal orientation. The contrast in texture though located is not felt by the observers indicating that the cortex is capable of guiding behavior without actual awareness.

Analysis, Observations, Visual perception, Visual cortex, Contrast sensitivity (Vision)

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Motion-induced blindness in normal observers

Article Abstract:

Research into the phenomenon of 'visual disappearance' seen with normal-sighted observers under natural conditions is presented. It was found that this motion-induced blindness (MIB) is probably not the result of sensory suppression or local adaptation. Under MIB conditions, the visual system moves to function in a winner-takes-all mode.

Vision disorders

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