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Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye [1]. A blind spot, scotoma, is an obscuration of the visual field.A particular blind spot known as the physiological blind spot, "blind point", or punctum caecum in medical literature, is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the ...
Location of Bjerrum's area, and common types of scotomas. Bjerrums area is marked with a dotted blue line at 25 degrees.. Bjerrum's area is the central 25° of the visual field from the fixation point, popularized scientifically by the Danish ophthalmologist Jannik Petersen Bjerrum.
A scotoma may include and enlarge the normal blind spot. Even a small scotoma that happens to affect central or macular vision will produce a severe visual disability, whereas a large scotoma in the more peripheral part of a visual field may go unnoticed by the bearer because of the normal reduced optical resolution in the peripheral visual field.
Vision remains normal beyond the borders of the expanding scotoma(s), with objects melting into the scotoma area background similarly to the physiological blind spot, which means that objects may be seen better by not looking directly at them in the early stages when the spot is in or near the center. The scotoma area may expand to occupy one ...
The blind spot can also be assessed via holding a small object between the practitioner and the patient. By comparing when the object disappears for the practitioner, a subject's blind spot can be identified. There are many variants of this type of exam (e.g., wiggling fingers in the visual periphery on the cardinal axes).
Blind spot (vision), also known as the physiological blind spot, the specific scotoma in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the optic disc Optic disc , also known as the anatomical blind spot, the specific region of the retina where the optic nerve and blood vessels pass through to connect to ...
Bjerrum tangent screen: Screen used to assess the central 30° of the visual field. Bjerrum's area: An arcuate region that extends above and below the blind spot to between 10° and 20° of fixation point. After Bjerrum's retirement in 1910, his work in campimetry was continued by his assistant, Henning Rønne (1878-1947).
[27] [4] [28] [dubious – discuss] The blind spot is at about 15.5° in the outside direction (e.g. in the left visual field for the left eye). [29] The grain of a photographic mosaic has just as limited resolving power as the "grain" of the retinal mosaic. To see detail, two sets of receptors must be intervened by a middle set.