The Developement of An Objective Test for Visual Acuity Assessment Using Optokinetic Nystagmus Stimuli Presented Head-Mounted Display: Seohan Objective Visual Acuity Test

The objective visual acuity test is mandatory in certain cases, such as infants, nonverbal subjects and subjects who need legal judgements. To produce more reliable objective method, we made a new objective system for visual acuity test which is called Seohan visual acuity test(SVT). The SVT system has three elements such as stimuli, display and evaluation. For the visual stimuli, the computer program for optokinetic nystagmus(OKN)test was set up in personal computer to control the size, speed and direction of the stimuli easily. The visual stimuli are presented on HeadMounted-Display(HMD)to separate the stimuli from the environment to keep the uniform size and distance of screen to the eye of subjects and project the stimulus in full central field of patient. Electrooculography(EOG) was used to assess the visual acuity more objectively. To evaluate the usefulness of SVT, the smallest size of the stimulus to elicit OKN(objective visual acuity)with SVT was obtained in 10 eyes in each twelve grade of subjective visual acuity(decimal V). Objective visual acuity(VA)were distributed from 8.3+/-1.87 to 21.4+/-3.1 and showed high correlation(p<0.00 ). The relationship between the objective VA obtained from SVT and subjective VA make a regression line(y=-12.874X+21.303).Subjective VA could be obtained from conversion of objective VA with 95%confidence belt. In conclusion, the objective visual acuity with SVT is highly correlated with subjective visual acuity and SVT using the OKN response to stimuli presented on HMD by the computer program can be useful in assessing visual function objectively.

Seohan Computerized Hue Test 1: The Development of Computerized Color Vision Test and Pilot Study

Several tests have been used for assessing color vision but most of them are nonspecific, expensive, complicated or too time consuming to perform. We have developed a new computerized color vision test named Seohan computerized 85-hue test[SCHT/85]that has many advantages compared to Farnsworth Munsell[FM]100-hue test.SCHT/85 has 85 color caps which can be displayed based on a model of FM 100-hue test using Multimedia toolbook 4.0.Selected color caps in the lower random area can be moved and inserted to the upper result area by a mouse.At the end of the test, error scores and ring graph can be displayed in monitor and can be also printed out. Total 15 subjects performed with SCHT/85 and FM 100-hue test twice who have been showed 10 normal and 5 abnormal color vision reported with other color vision tests and the results of two tests were analysed to compare the total error scores[TES]and reproducibility. All ten normal subjects showed lower TES in SCHT/85 than FM 100-hue test and the mean TES were 31.5 and 43.6 with SCHT/85 and FM 100-hue test.The coefficients of variation [CV]were 4.3%and 22.7%with SCHT/85 and FM 100-hue test.The two tests were highly correlated[r=0.92].Five abnormal subjects showed higher TES in SCHT/85 than FM 100-hue test and the mean TES were 169.8 and 157.3 with SCHT/85 and FM 100-hue test.The coefficients of variation were 9.1%and 21.2%with SCHT/85 and FM 100-hue test.These two tests were also highly correlated[r=0.965]. In conclusion, SCHT/85 which was newly developed by authors is a highly useful test for color vision.