optotype


Also found in: Dictionary, Wikipedia.

optotype

(ŏp′tō-tīp)
The variable-sized type used in testing visual acuity.

Patient care

Figures, letters, numbers, or pictures may be used in optotype tests of visual acuity. Traditionally the symbols have been printed on a wall-mounted card and presented to the patient to identify, e.g., the Snellen test. The patient stands at a predetermined distance (usually 20 ft.) from the symbols, covers one eye, and then reads or interprets the symbols for the examiner, and then repeats the process covering the other eye. In illiterate patients or young children directional symbols may be used, e.g., "tumbling E's" instead of numbers or randomly chosen letters of the alphabet. Optotype testing is subject to a number of flaws, e.g., patients may try to memorize listed letters or objects to improve their scores; alternately, some patients with learning disabilities may not understand how to respond to the test.

optotype 

Test type used for measuring visual acuity. See monotype visual acuity; Snellen chart; Jaeger test types; König bars; Landolt ring.
References in periodicals archive ?
The procedure followed for applying the P&R test consisted of all the participants in the study reading (in monocular and binocular vision) the letters located on the optotype, beginning with the top row and continuing until two of the three letters in the same group were read incorrectly.
Kay Pictures are the most commonly used optotype test for young children in the UK.
Images included Lea symbols (circle, square, house, or apple; Figure 1(a)), posted on a 15-line vision optotype chart [24].
However, the testing becomes much easier as the children understand optotypes and communicate better, and the possibilities for optometric management improve since children become more likely to cooperate with spectacle wear or eye exercises.
3-5 years: Matching optotypes (use the illiterate E chart, Landolt's C test, Sheridan-Gardener's test, Lea charts).
The 4-m chart used had high contrast Sloan letters and optotypes were in LogMAR increments.
3) This is perhaps because Snellen VA is measured with high contrast static optotypes, very unlike natural conditions of the "number plate test", making Snellen VA a poor predictor of a person's ability to meet the legal driving standard.
BCVA with Early Treatment Diabetic Retinopathy Study optotypes (Precision Vision; La Salle, Illinois) ranged from 20/10 to 20/125; 82 percent were 20/20 or better.
Grating acuity was measured with persons with severe disabilities only if it was not possible to use optotypes.
a) The spacing of the optotypes and the lines follows a geometric progression
One or more sessions with an occupational therapist were devoted to training in reading skills with suprathreshold optotypes (larger than critical print size) or continuous print materials.
Indeed, logMAR charts such as the Bailey-Lovie chart are advantageous in that task difficulty remains consistent across all levels of acuity, with equal number of optotypes presented per line, and there is a regular logarithmic progression of acuity such that each line is a scaled version of the preceding line, allowing each individual letter to contribute to the VA measure, increasing the accuracy.