optotype


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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 subject of the public contract is the delivery of one piece of Snell's digital optotype.
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.
Images included Lea symbols (circle, square, house, or apple; Figure 1(a)), posted on a 15-line vision optotype chart [24].
Enrolled subjects underwent unaided visual acuity testing for distant vision using snellen's chart and near vision Optotype chart.
3) It is, therefore, important to perform an optotype test with crowding, when a child is old enough.
1997, for basal ganglion disorders; Ek, Fellenius, & Jacobson, 2003, and Jacobson & Dutton, 2000, for improved optotype acuity for PVL).
Lot 1: Angiograph-October- Lot 2: corneal topographers- Lot 3: Slit Lamp with a picture Digestive- Lot 4: Slit Lamps (3)- Lot 5: Screens optotype (10)
For letter charts, factors such as the optotype design, spacing and interaction effects from adjacent visual contours (crowding) can all affect visual acuity measurement.
But these methods of assessing acuity are not as good at detecting strabismic amblyopia as crowded optotype tests and, as soon as possible, this type of test should be used.
The letters can be interchanged for different languages, while it also allows the user to change the optotypes to the universal language of numbers.
A functional scale seems essential for preschool children with visual impairments whose visual acuity cannot be recorded using optotypes.
Children less than 2 years with good co-operation and response Lea paddles, 2-4 years Lea symbols or single optotypes such as Landolt C or HOTV (Simson 1983) was used and above 5 years Snellen's chart was used.