Threshold exposure duration for recognition of test objects in children with various refractive statuses
V.I. Serdiuchenko, Dr Sc (Med)
M.B. Zheliznik, Graduate Student
Filatov Institute of Eye Disease and Tissue Therapy,
Backup: The speed of visual information processing is of primary importance today.
Purpose: To determine the threshold exposure duration for recognition of test objects (TEDRTO) values in children with various refractive statuses.
Materials and Methods: Seventy one children (22 hyperopes, 26 myopes, and 23 emmetropes; 142 eyes totally) aged 7 to 13 years underwent TEDRTO measurements with the electronic apparatus. A child fixated on a test object (TO) subtending 160, 40 or 8 minutes of arc (ma).
Results: The monocular TEDRTO values in emmetropes, hyperopes and myopes were 1.0 ms with a TO subtending 160 ma; 1.4±0.2 ms, 1.8±0.2 ms and 1.8±0.2 ms, respectively, with a TO subtending 40 ma; and 7.8±1.1 ms, 14.9±1.3 ms, and 7.9±1.0 ms, respectively, with a TO subtending 8 ma. Binocular TEDRTO values tended to be lower than monocular ones for optotypes subtending 40 and 8 ma.
Conclusion: TEDRTO values were found to increase significantly as the visual angle subtended by the TO decreased, which could be explained by a longer time required for recognition of a high-frequency image compared to that of a low-frequency image. Significantly higher TEDRTO values in hyperopes compared to emmetropes and myopes (P<0.05) might be explained by the involvement of accommodation in the mechanism of TO recognition in hyperopes.
Key words: threshold exposure duration for recognition of test objects, refractive anomalies, emmetropia, hyperopia, myopia
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