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The visual field index (VFI) reflects retinal ganglion cell loss and function, as a percentage, with central points weighted more. [21] It is expressed as a percentage of visual function; with 100% being a perfect age-adjusted visual field and 0% represents a perimetrically blind field.
Perimetry or campimetry is one way to systematically test the visual field. [1] [failed verification] It is the systematic measurement of differential light sensitivity in the visual field by the detection of the presence of test targets on a defined background. Perimetry more carefully maps and quantifies the visual field, especially at the ...
The visual field is "that portion of space in which objects are visible at the same moment during steady fixation of the gaze in one direction"; [1] in ophthalmology and neurology the emphasis is mostly on the structure inside the visual field and it is then considered “the field of functional capacity obtained and recorded by means of perimetry”.
Microperimetry, sometimes called fundus-controlled perimetry, [1] is a type of visual field test [2] which uses one of several technologies to create a "retinal sensitivity map" of the quantity of light perceived in specific parts of the retina [3] in people who have lost the ability to fixate on an object or light source.
The Swedish interactive thresholding algorithm, usually referred to as SITA, is a method to test for visual field loss, usually in glaucoma testing or monitoring. [1] It is combined with a visual field test such as standard automated perimetry (SAP) or short wavelength automated perimetry (SWAP) to determine visual fields in a more efficient ...
Fixation or visual fixation is the maintaining of the gaze on a single location. An animal can exhibit visual fixation if it possess a fovea in the anatomy of their eye. The fovea is typically located at the center of the retina and is the point of clearest vision. The species in which fixational eye movement has been verified thus far include ...
Peripheral vision is usually spared since the pattern of loss typically involves a central or cecocentral scotoma, a visual field defect at or surrounding the point of fixation. This pattern can be revealed via visual field testing. Upon examination, the pupils usually demonstrate a normal response to light and near stimulation. In those who ...
The vertical meridian runs from above the observer's line of sight, through the fixation point, and to below the observer's line of sight. Another way of thinking of the maximum visual field is to think of all of the retina that can be reached by light from the external environment. The visual field in this case is all of the external ...