Definition of Visual Acuity

Visual Acuity – the ability to see objects clearly and sharply. Visual acuity assesses central vision and represents the function of the cornea, iris (pupil size), lens, and retina. the snellen chart, which presents lines of letters of diminishing size, is the standard measure of visual acuity. Environmental factors that influence visual acuity include lighting and contrast.

The most common disturbances of visual acuity are refractive errors such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (blurred vision). Presbyopia, age-related changes in the cornea’s flexibility, affects near-vision visual acuity.

See also NIGHT BLINDNESSVISION IMPAIRMENT.

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