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Near visual acuity or near vision is a measure of how clearly a person can see nearby small objects or letters.Visual acuity in general usually refers clarity of distance vision, and is measured using eye charts like Snellen chart, LogMAR chart etc. Near vision is usually measured and recorded using a printed hand-held card containing different sized paragraphs, words, letters or symbols.
An example of the Landolt C eye chart (also known as the Japanese eye chart). Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision, while the ETDRS chart is designed for use at 4 meters. [16]
(Top) 0.50 confirmation set; (Middle) trial lens box, including pinhole and occluder; (Bottom) Snellen chart. Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). [1]
A person taking the test covers one eye from 6 metres or 20 feet away, and reads aloud the letters of each row, beginning at the top. The smallest row that can be read accurately indicates the visual acuity in that specific eye. The symbols on an acuity chart are formally known as "optotypes". Variation of Snellen chart with another letter ...
OH Ocular history OMB Oculo motor balance ONH Optic nerve head Oph Ophthalmoscopy OS oculus sinister (left eye) OU oculus uterque (both eyes) PD Pupillary distance PERRLA Pupils equal, round, reactive to light and accommodation PH Pinhole see Pinhole occluder and Visual_acuity#Legal_definitions: PHNI Pinhole No Improvement
Sloan letters, designed by Louise Sloan in 1959, are a set of optotypes used to test visual acuity generally used in Snellen charts and logMAR charts. This set of optotypes consists of ten specially formed "letters", C, D, H, K, N, O, R, S, V and Z. [ 1 ] These letters, unlike the ones used in older Snellen charts, are designed to give acuity ...
Snellen chart. The Snellen chart, which dates back to 1862, is also commonly used to estimate visual acuity.A Snellen score of 6/6 (20/20), indicating that an observer can resolve details as small as 1 minute of visual angle, corresponds to a LogMAR of 0 (since the base-10 logarithm of 1 is 0); a Snellen score of 6/12 (20/40), indicating an observer can resolve details as small as 2 minutes of ...
The Jaeger chart is an eye chart used in testing near visual acuity.It is a card on which paragraphs of text are printed, with the text sizes increasing from 0.37 mm to 2.5 mm. [1] This card is to be held by a patient at a fixed distance from the eye dependent on the J size being read.