Sharpness of vision, most often determined by use of the Snellen chart.
The ability to distinguish details and shapes. Measurement of visual acuity is part of a standard eye examination.
Sharpness of vision. How well one sees things depends on how well they are illuminated and upon such factors as practice and motivation, but the essential requirements are a healthy retina and the ability of the eye to focus incoming light to form a sharp image on the retina. The commonest way of assessing visual acuity is the Snellen chart, which measures the resolving power of the eye.
A measure of the resolving power of the eye. It is usually determined by one’s ability to read letters of various sizes at a standard distance from the test chart. The result is expressed as a comparison: for example, 20/20 is normal vision, meaning the subject has the ability to see from a distance of 20 ft (6. 1 m) what a person with normal vision should see at that distance. Visual acuity of 20/40 means that a person sees at 20 ft (6.1 m) what a person with normal vision sees from a distance of 40 ft (12.2 m).
Clarity of vision. Acuity is measured as a fraction of normal vision. 20/20 vision indicates an eye that sees at 20 feet what a normal eye should see at 20 feet; 20/400 vision indicates an eye that sees at 20 feet what a normal eye sees at 400 feet.
The eye’s capability to distinguish and separate nearby objects, often described in terms of an angle, is referred to as visual resolution. This ability allows us to perceive distinct details and discern individual elements within a given field of view. Visual resolution is quantified by measuring the angular separation required to perceive two adjacent objects as separate entities, reflecting the eye’s resolving power in differentiating fine details.
Clarity of central vision is often impacted by refractive errors like shortsightedness (myopia), longsightedness (hypermetropia), and abnormal eye curvature (astigmatism), which are the typical reasons for reduced visual acuity. The inability to clearly see objects up close is commonly due to presbyopia, a condition associated with age-related decline in focusing ability.
The level of vision a patient possesses.