This study aims to investigate visual tracking task of Koreans to the various visual stimuli by measuring the horizontal saccadic reaction times. The measuring system consists of eye monitor using infra-red reflection technique, oscillographic recorder and forehead-chin fixation devices. The visual stimuli generated by target function generator displayed simple-step, pulsestep and double-step stimulus patterns. The results revealed that the sacoadic reaction time showed no significant changes between the size of target displacement within horizontal 20 degrees. Furthermore, no significant changes between the particular direction of stimulus could be found. The nominal value of reaction time was 259 +/- 25 msec.
Reaction Time

Among 8, 350 patients seen in the department of ophthalmology, Yonsei University Medical Center from August 1, 1968 to July 31, 1971 there were 2,313 who were seen because of refractive error. These were selected for classification and special statistical study. We reported two similar studies of 2,004 patients having errors in refraction among a total of 9,716 patients seen from August 1, 1958 to July 31, 1961 and 1,919 patients having errors in refraction among a total of 8,796 patients from August 1, 1965 to July 31, 1968 seen in the same department in 1962 and 1968 respectively. The finding of the more recently studied groups are compared with the studies made in 1962 and 1968. 1. 2,313 out of 8,350 patients seen in the department of ophthalmology had errors in refraction (27.7%). 2. 2,949 cases (63.8%) had refractive errors of the myopic type. 626 cases (13.5%) were hyperopic. The others had a simple and a mixed astigmatism. 3. 61.2% of the total group studied had astigmatism. 4. The highest incidence of refractive errors was found between 11 and 20 years of age The older patients had a low incidence. 5. Among the total number of refractive errors 56.3% were found to be in myopic patients who had less than a -3.00 diopters error. 16.8% were found among hyperopic patients who had less than a +3.00 diopters error. 6. Among the three types of astigmatic error seen 1,507 cases (53.2%) were "with the rule", 872 cases (30.8%) were "against the rule", and 456 cases (16.0%) were "oblique". 7. 6.9% of the total refractive errors were those of different types of anisometropia. The most commonly seen type was that of compound myopic anisometropia. The next type seen was simple myopic anisometropia and the least frequently seen type was compound hyperopic anisometropia. 8. When the results of the present study were compared with those found in 1962 and 1968 there are no significant difference between these three groups.
Academic Medical Centers ; Anisometropia ; Astigmatism ; Classification ; Humans ; Incidence ; Ophthalmology ; Refractive Errors ; Statistics as Topic