visual acuity

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1. Acuteness (see acute [def. 2]); the level of severity of an illness. This is one of the parameters considered in patient classification systems that are designed to serve as guidelines for allocation of nursing staff, to justify staffing decisions, and to aid in long-range projection of staffing and budget.
2. clearness of the visual perception of an image.
visual acuity the ability to discriminate visually between forms.
 Visual field chart illustrating the divisions of the visual field related to visual acuity. (Courtesy of Josephine C. Moore, PhD, OTR.) From Pedretti and Early, 2001.

res·o·lu·tion a·cu·i·ty

detection of a target having two or more parts, often measured by using the Snellen test types; indicated by two numbers: the first represents the distance at which a patient sees the test types (usually 6 m. or 20 ft.), and the second, the distance at which the test types subtend an angle of 5 min.; for example, vision of 6/9 indicates a test distance of 6 m. and recognition of symbols that subtend an angle of 5 min. at a distance of 9 m.
Synonym(s): visual acuity

visual acuity

Sharpness of vision, especially as tested with a Snellen chart. Normal visual acuity based on the Snellen chart is 20/20.

visual acuity

Etymology: L, visus, vision, acuitas, sharpness
1 a measure of the resolving power of the eye, particularly with its ability to distinguish letters and numbers at a given distance.
2 the sharpness or clearness of vision.

visual acuity

Central vision Ophthalmology The ability to distinguish details and shapes of objects; a measure of the ability to resolve distinct objects or fine details with the eye

vis·u·al a·cu·ity

(vizh'ū-ăl ă-kyū'i-tē)
Sharpness or clarity of vision, measured as the ability to distinguish letters or other images of various sizes at a fixed distance, usually with a Snellen chart. Normal rating by such means is 20/20 vision.

visual acuity

The extent to which an eye is capable of resolving fine detail. Visual acuity is measured by means of a SNELLEN'S CHART TEST.

Visual acuity

The ability to distinguish details and shapes of objects.
Mentioned in: Amblyopia, Myopia, Presbyopia


Inability to recognize the import of sensory stimuli (e.g. to recognize colour, faces, shape and the orientation of objects), although the receptors and the sensory pathway are intact. The condition is attributed to bilateral lesions in the association areas of the cortex. If the sense of sight is affected, it is called visual agnosia (perceptual or psychic blindness). See alexia; optical apraxia; prosopagnosia.


Inability to write, usually as a result of a brain lesion. If the person can write from dictation but not from copying, it is called visual agraphia.

vis·u·al a·cu·ity

(vizh'ū-ăl ă-kyū'i-tē)
Sharpness or clarity of vision, measured as the ability to distinguish letters or other images of various sizes at a fixed distance, usually with a Snellen chart. Normal rating by such means is 20/20 vision.
References in periodicals archive ?
Isaac Lipshitz) is indicated for monocular implantation to improve vision in patients greater than or equal to 65 years of age with stable severe to profound vision impairment (best-corrected distance visual acuity 20/160 to 20/800) caused by bilateral central scotomas (blind areas) associated with end-stage AMD.
Best-corrected vision (with current spectacles) was assessed using the Lighthouse Ferris-Bailey Early Treatment Diabetic Retinopathy Study chart to measure visual acuity and the Pelli-Robson Contrast Sensitivity chart to measure contrast sensitivity.
5, it will be allowable for designers to design to reduced illuminances, to maintain the same visual acuity as presumed in the IES Illuminance Determination System.
At each visit, the visual acuity and objective refraction were recorded by an ophthalmic technician or nurse, and slit-lamp examination of the anterior segment and fundus was undertaken by the surgeon.
The gold standard for visual acuity testing in adults is the Early Treatment of Diabetic Retinopathy Study (ETDRS) optotype [26-27].
5 mg ranibizumab lost fewer than 15 letters in visual acuity from baseline versus 53 percent of patients in the placebo controlled group.
The World Health Organization (WHO/estimates that approximately 124 million people have low vision, which it defines as visual acuity between 20/60 and 20/400 with the best possible correction or a visual field of 20 degrees or less.
Not everyone is color-perceptive; others might have visual acuity or mobility issues that might prevent them from having easy access to information.
Visual acuity, depth perception, contrast sensitivity, and peripheral vision decline with age and these changes reduce or alter the environmental data your brain uses to maintain balance.
Particularly practical and potentially most helpful to persons with MS are his discussions on how the eye works, what different levels of visual acuity mean with regard to function, and how the use of proper lighting, head positioning, and the best possible glasses/contact lens prescription can work to maximize visual function.
Final visual acuity was 20/25 or better in 6 patients, 20/30 to 20/50 in 2 patients, 20/60 to 20/100 in 2 patients, and 20/200 in 1 patient.
According to the investigators, 45% of the implanted eyes had visual acuity of 20/20 or better, and 84% had visual acuity of 20/40 or better.