• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.241-245
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• 2010

Purpose: In this work we suggested a grating chart of vision test which could be used to measure the sense of distance and motion of object. Methods: A couple of gratings with periodic structure were fabricated. Through a lens the grating images showing geometrical shapes were projected on a vision test chart in order to form a new grating chart of vision test. In rotating and translating the gratings the examinee perceived the variation of position of gratings by the variation of the sense of distance and motion. Results: The results of the sense of distance and motion measured in rotating and translating the gratings showed the average errors of ~2.98% and ~1.73% at $\theta=15^{\circ}$ respectively compared to calculated values. Conclusions: The grating chart of vision test suggested in this work can be used as a new test chart that lets an examinee perceive a sense of distance and motion of object.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.61-67
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• 2007

The binocular functional test was performed in test of both accommodation and convergence. The balance of accommodation and convergence was important. Objects were 100 adults in 18-36 years old ages. The used apparatus was vision tester(Shinnippon VT10)and visual chart(Shinnippon CT30). Accommodative lag test by fused cross cylinder were that in case of high 39.0%, in case of low 14.0%. Negative relative accommodation were that in case of high 23.0%, in case of low 38.0%. Positive relative accommodation were that in case of high 29.0%, in case of low 23.0%. In 18% were case of low accommodation.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.2
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• pp.111-118
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• 2005

The optotypes widely used as a necessity in the course of optometry are the world authorized versions which contain items such as the Landolt's rings, Snellen's chart and also Arabian numbers, Korean letters, Pictures and so on. In Korea, the Hahn-chun-suk test chart has been In use generally alolng with Chung-san test chart and Jin-yong-han test chart also in use on the wall. But these sort of test charts hung on the wall have some problems such as the difference in test results owing to the rate of illumination and so a more accurate method is required. To solve the problem of inaccuracy in optometry, the projected type of charts with digital instrument such as the beam projector has been developed lately. This chart projector with consistent high resolution and the ability to provide various charts can help eye examiner perform effective examination and thus is looked positively upon as the automated total optometry system. So in this study our purpose is to examine the accuracy of the projected chart. It was done by comparing it with the frequently used test chart. The results of experiment are as follow. When the projected chart was used, cases that subject read charts one step higher were 10%, two step higher 2% than perfectly corrected vision. When Han-chun-suk test chart was used, cases that subject read charts one step higher were 12%, and two step higher were 4%.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.4
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• pp.115-119
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• 2008

Purpose: To compare the tentative and final addition, a combination chart of cross-grid and red green with the final addition prescribed in presbyopia were used in this study. Methods: The study subjects were 60 persons with presbyopia who were 41 to 60 years (mean: 51.7 years). Tentative addition were determined using red green chart (RG), cross-grid chart (CG) and the combination chart (red green cross-grid chart, RGCG) of the above two. And the final addition for a 40 cm working distance was determined for each subject by adjusting the tentative addition. Results: It was found that there were statistically significant differences of the final addition and the tentative addition between the each different test method. This result indicated that using the red-green cross-grid chart is the higher repeatability. Conclusions: This study shows that red green cross-grid chart (RGCG) seems to be get proper data for determining addition in presbyopes, and this method would be helpful in the diagnostic evaluation of addition in binocular vision testing.

• Journal of Biosystems Engineering
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• v.32 no.4
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• pp.256-262
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• 2007

Image processing systems have been used to measure the plant parameters such as size, shape and structure of plants. There are yet some limited applications for evaluating plant colors due to illumination conditions. This study was focused to present adaptive methods to analyze plant leaf color regardless of illumination conditions. Color patches attached on the calibration bars were selected to represent leaf colors of lettuces and to test a possibility of health monitoring of lettuces. Repeatability of assigning leaf colors to color patches was investigated by two-tailed t-test for paired comparison. It resulted that there were no differences of assignment histogram between two images of one lettuce that were acquired at different light conditions. It supported that use of the calibration bars proposed for leaf color analysis provided color constancy, which was one of the most important issues in a video color analysis. A health discrimination equation was developed to classify lettuces into one of two classes, SOUND group and POOR group, using the machine vision. The classification accuracy of the developed health discrimination equation was 80.8%, compared to farmers' decision. This study could provide a feasible method to develop a standard color chart for evaluating leaf colors of plants and plant health monitoring system using the machine vision.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.3
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• pp.269-274
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• 2010

Purpose: The repeatability of a new Red-Blue phoria chart test (Red-Blue phoria chart; RBP) was appreciated. Methods: Distance (5 m) and near (40 cm) heterophoria was measured in 38 visually normal subjects. Phoria tests using RBP, Howell phoria card (HP), and MIM card (MIM) were done and the repeatability of each phoria test was compared with one another. Results: The mean of horizontal deviations was that RBP was $-0.602{\pm}0.727{\Delta}$, HP was $-0.865{\pm}1.051{\Delta}$, and MIM was $-1.501{\pm}1.346{\Delta}$, at distance, and that RBP was $-2.566{\pm}2.352{\Delta}$, HP was $-2.804{\pm}2.411{\Delta}$, MIM was $-3.838{\pm}2.603{\Delta}$, at near. The repeatability was RBP>MIM>HP in distance tests and MIM>RBP>HP in near tests. Conclusions:RBP test is identified as a reliable phoria test having high repeatability.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.1
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• pp.101-105
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• 2008

Purpose: In this study we measured the mean value of the distance stereoacutiy for adult subjects and evaluated the variation of the distance stereoacuity according to correction of phoria using the Pola Test E-II of Carl Zeiss. Methods: We investigated the distance stereoacuity for 50 adults (male: 29, female: 21) ranging in age from 19 to 46 years using D6 Circle chart and D8 Line chart in the Pola Test E-II. Results: The mean values of the distance stereoacuity measured on the D6 Circle test and D8 Line test were 159.6 and 149.4 seconds of arc respectively. The mean variations of the distance stereoacuity according to correction of phoria in D6 Circle test were increased 43.2 seconds of arc in exophoria and 51 seconds of arc in esophoria, and those in D8 Line test were increased 42 seconds of arc in exophoria and 70.2 seconds of arc in esophoria. Conclusions: We knew from these results that the distance stereoacuity after prescription of phoria improved more esophoria than exophoria.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.17-22
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• 2014

Purpose: We aimed to evaluate reliability of eye exam for visual acuity as a function of distance. Methods: There were 39 patients (78 eyes) who had visual acuity 1.0 or more at 5 meters. We measured refractive power of patients at each distances, 5 meters, 4 meters and 3 meters. Automatic chart (LCD-700, Hyeseong Optic. Co., Korea) used for visual acuity, skiascope (Beta 200, Heine, Germany) and auto refractometer (RK-5, Canon, Japan) used as for objective refraction. Accommodation was examined by minus lens addition methods, and Accommodative lag was examined by grid chart for reading distance. Results: Being compared to 3 meter test, Amount of corrected spherical refractive power decreased by $0.10{\pm}0.38$ D, astigmatism decreased by $0.05{\pm}0.10$ D, and axis of astigmatism rotated toward to temporal by $2.64{\pm}18.75$ degrees for right eyes, by $11.43{\pm}48.55$ degrees for left eyes in case of 5 meter test. Changes of corrected refraction and astigmatism were slightly correlated (r=-0.31, r=-0.29). Conclusions: Because corrected refraction power and amount of astigmatism decreased and axis of astigmatism tends to turn the temporal direction according to exam distance, examination distance of visual acuity should improved as to 5 meters.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.381-388
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• 2010

Purpose: This study was to compare the contrast sensitivity evaluated the visual ability at near wearing functional lenses for pre-presbyopes altered their single vision lenses to functional progressive addition lenses with low addition for 2 months. Methods: Healthy 32 subjects aged 24.03${\pm}$1.87 (male 23, female 9) who were recruited from university students wore functional progressive addition lenses(EYE-T, Chemilens Co., Korea, ADD 0.75D) for 2 months. Corrected visual acuity at distance and near and contrast sensitivity at near were tested right after wearing functional progressive addition lenses to compare wearing single vision lenses. And we had second test after 2 months later. Results: Comparing between test and retest, contrast sensitivity at near wearing functional progressive addition lenses was improved more than wearing single vision lenses at all spatial frequency of right, left and both eyes. Conclusions: There was considered that contrast sensitivity test is useful to evaluate the visual ability as well as quality of near work and can be applied variously.

• Journal of Preventive Medicine and Public Health
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• v.25 no.3 s.39
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• pp.247-268
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• 1992

This study was conducted to evaluate the effect of VDT work on eyes and vision among workers in a TV manufacturing plant. The study subjects consisted of 264 screen workers and 74 non-screen workers who were less than 40 years old male and had no history of opthalmic diseases such as corneal opacities, trauma, keratitis, etc and whose visual acuity on pre-employment health examination by Han's test chart was 1.0 or above. The screen workers were divided into two groups by actual time for screen work in a day : Group I, 60 workers, lesser than 4 hours a day and group II, 204 workers, more than 4 hours a day. From July to October 1992 a questionnaire was administered to all the study subjects for the general charateristics and subjective eye symptoms after which the opthalmologic tests such as visual acuity, spherical equivalent, lacrimal function, ocular pressure, slit lamp test, fundoscopy were conducted by one opthalmologist. The proportion of workers whose present visual acuity was decreased more than 0.15 in comparison with that on the pre-employment health examination by Han's test chart was 20.6% in Group II. 15.0% in Group I and 14.9% in non-screen workers. However, the differences in proportion were not statistically significant. The proportion of workers with decreased visual acuity was not associated with the age, working duration, use of magnifying glass and type of shift work (independent variables) in all of the three groups. However, screen workers working under poor illumination had a higher proportion of persons with decreased visual acuity than those working under adequate illumination (P<0.05) . The proportion of workers whose near vision was decreased was 27.5% in Group II, 18.3% in Group I, and 28.4% in non-screen workers and these differences in proportion were not statistically significant. Changes of near vision were not associated with 4 independent variables in all of the three groups. Six out of seven subjective eye symptoms except tearing were more common in Group I than in non-screen workers and more common in Group II than in Group I (P<0.01). Mean of the total scores for seven subjective symptoms of each worker(2 points for always, 1 point for sometimes, 0 point for never) was not significantly different between workers with decreased visual acuity and workers with no vision change. However, mean of the total scores for Group II was higher than those for the Group I and non-screen workers (P<0.01). Total eye symptom scores were significantly correlated with the grade of screen work, use of magnifying glass, and type of shift work. There was no independent variable which was correlated with the difference in visual acuity between the pre-employment health examination and the present state, the difference between far and near visions, lacrimal function, ocular pressure, and spherical equivalent. Multiple linear regression analysis for the subjective eye symptom scores revealed a positive linear relationship with actual time for screen work and shift work(P<0.01). In this study it was not observed that the VDT work decreased visual acuity but it induces subjective eye symptoms such as eye fatigue, blurred vision, ocular discomfort, etc. Maintenance of adequate illumination in the work place and control of excessive VDT work are recommended to prevent such eye symptoms.