The Size and Location of the Normal Blind Spot

Armaly, Mansour F.

doi:10.1001/archopht.1969.00990010194009

Cited by 47 publications

(24 citation statements)

References 5 publications

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“…This strategy however is still considered to be of limited value in accurately defining the immediate surroundings of the blind spot. The relative uncertainty remaining despite a sophisticated computer analysis confirms Armaly's assumption (1), that the determination of the blind spot, according to conventional manual kinetic techniques does not provide any information of much diagnostic value at all.…”

Section: Discussionsupporting

confidence: 57%

Researches on adaptive high resolution programming for automatic perimeter

1980

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Two adaptive perimetric strategies for the search and the analysis of scotomata have been developed and tested over the normal and pathologically disturbed blind spot area. Adaptive procedures automatically concentrate their search effort upon areas of pathological disturbance and avoid time loss used for declaring normal areas as such. Provided a first scan of low spatial resolution, detects only one edge of the blind spot, spatial resolution increases and analyses the blind spot, returning to low resolution as soon as the border of the blind spot is crossed and normal sensitivity is again attained. Two adaptive strategies are described. One reduces examination duration to 1/2, the other to about I/3 when compared to a similar non adaptive high resolution strategy. Only in the latter this time reduction has to be paid by some loss of information. The accuracy of the threshold determination method described is limited whereas spatial precision is high. Hence a more accurate threshold determination technique has to be added if the postulate of great threshold accuracy is to be fulfilled.

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Section: Discussionsupporting

confidence: 57%

Researches on adaptive high resolution programming for automatic perimeter

1980

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“…We used eccentric targets to avoid ceiling effects as central targets were recognized at very high rates under all conditions. The typical location of the blind spot in the visual field is 1.5 degrees below the horizontal meridian at 16 degrees of eccentricity on the temporal side, and its typical size is 10 degrees vertically by 7 degrees horizontally [18]. Therefore the target object slightly overlapped the blind spot for 2 of the outermost right and 2 of the outermost left target locations.…”

Section: Methodsmentioning

confidence: 99%

Stereoscopic Offset Makes Objects Easier to Recognize

Caziot

Backus

2015

PLoS ONE

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Binocular vision is obviously useful for depth perception, but it might also enhance other components of visual processing, such as image segmentation. We used naturalistic images to determine whether giving an object a stereoscopic offset of 15-120 arcmin of crossed disparity relative to its background would make the object easier to recognize in briefly presented (33-133 ms), temporally masked displays. Disparity had a beneficial effect across a wide range of disparities and display durations. Most of this benefit occurred whether or not the stereoscopic contour agreed with the object’s luminance contour. We attribute this benefit to an orienting of spatial attention that selected the object and its local background for enhanced 2D pattern processing. At longer display durations, contour agreement provided an additional benefit, and a separate experiment using random-dot stimuli confirmed that stereoscopic contours plausibly contributed to recognition at the longer display durations in our experiment. We conclude that in real-world situations binocular vision confers an advantage not only for depth perception, but also for recognizing objects from their luminance patterns and bounding contours.

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“…At the two-year follow-up, the scotoma size among these GA patients matched the findings from other studies in general. Compared with the physiological blind spot, which is about 6 deg wide and 8 deg high (Armaly, 1969), in most cases, especially for more advanced stages of AMD, central scotomata have a much larger size. Also, according to Schuchard et al (1999), the scotoma width is usually larger than the scotoma height and thus the scotoma looks like a horizontally oriented ellipse.…”

Section: Characteristics Of Central Scotomamentioning

confidence: 98%

Functional and cortical adaptations to central vision loss

2005

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Age-related macular degeneration (AMD), affecting the retina, afflicts one out of ten people aged 80 years or older in the United States. AMD often results in vision loss to the central 15-20 deg of the visual field (i.e. central scotoma), and frequently afflicts both eyes. In most cases, when the central scotoma includes the fovea, patients will adopt an eccentric preferred retinal locus (PRL) for fixation. The onset of a central scotoma results in the absence of retinal inputs to corresponding regions of retinotopically mapped visual cortex. Animal studies have shown evidence for reorganization in adult mammals for such cortical areas following experimentally induced central scotomata. However, it is still unknown whether reorganization occurs in primary visual cortex (V1) of AMD patients. Nor is it known whether the adoption of a PRL corresponds to changes to the retinotopic mapping of V1. Two recent advances hold out the promise for addressing these issues and for contributing to the rehabilitation of AMD patients: improved methods for assessing visual function across the fields of AMD patients using the scanning laser ophthalmoscope, and the advent of brain-imaging methods for studying retinotopic mapping in humans. For the most part, specialists in these two areas come from different disciplines and communities, with few opportunities to interact. The purpose of this review is to summarize key findings on both the clinical and neuroscience issues related to questions about visual adaptation in AMD patients.

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The Size and Location of the Normal Blind Spot

Cited by 47 publications

References 5 publications

Researches on adaptive high resolution programming for automatic perimeter

Researches on adaptive high resolution programming for automatic perimeter

Stereoscopic Offset Makes Objects Easier to Recognize

Functional and cortical adaptations to central vision loss

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