This study was conducted to compare and analyze the effect of near visual media luminance on accommodative response (AR) and accommodative lag (AL) between emmetropia and myopia, and found out the near visual media to be caused burdensome on eyes in terms of AR and AL. Methods: Forty adult men and women (40 eyes) with ages averaging 22.57±2.07 years, who were not accommodative function disorder. 11 adults were emmetropes (average spheric equivalent power-0.34±0.22 D) and 29 adults were myopes (average spheric equivalent power-3.86±1.69 D). AR was measured and compared by using both eyes open view auto refractometer in the case looking at the near visual media (near standard target, print paper, newspaper, magazine, smartphone, monitor). Results: AR was lower and AL was higher in the case looking at the luminous visual media (smartphone, monitor) than the non-luminous visual media (near standard target, print paper, newspaper, magazine). AR (F=2.622, P=0.033) and AL (F=2.593, P=0.034) among different luminance of near visual media in emmetropes wear not statistically significant, However, AR was the lowest as 1.32±0.26 D (F=5.924, P=0.000), AL was the highest as 0.90±0.24 D (F=6.007, P=0.000) in the case looking at the monitor with the highest luminance and the widest screen size in myopes. Conclusions: When the myopes looking at the luminous visual media which includes high luminance and wide screen size is considered to be more burdensome on eyes than the emmetropes looking at the luminous visual media in terms of AR and AL.

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This study was conducted to research effects of influence factors on stereopsis of induced aniseikonia in emmetropia. Methods: 20 college students (a mean age of 22.50±2.72 years, 14 males, 6 females) were selected as subjects and all of them had no ocular disease or systemic disease, the refractive correction of spherical equivalent within ±0.50 D, the corrected visual acuity of 1.0 or better and the aniseikonia values less than 1% by AWAYA. Subject's dominant eye was checked by Hole in card method and contact lenses of −7.00 ~ +7.00 D were fitted to cause anisometropia in dominant eye or non-dominant eye, respectively. And then aniseikonia was induced with spectacles to correct refractive error by contact lenses. Stereopsis was measured by Random Dot Stereo Acuity Test with LEA symbols ® (Vision Assessment Corporation TM , USA). Results: Stereopsis was remarkably reduced by inducing aniseikonia, with induced aniseikonia in dominant eye, with higher diopter of wearing contact lenses to induce anisometropia, with spectacles lenses correction of minus power after fitting contact lenses with plus power and in case of men. Conclusions: It should be considered to correct anisometropia that aniseikonia could cause reduction of stereopsis.

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Purpose: The Purpose of this study is to investigate if the relative legibility of optotypes affects the corrected visual acuity in visual acuity test. Methods: After measuring the relative legibility of 'Landolt ring target', 'arabic number target', 'alphabet target' by showing as a single-letter-target in 24 subjects without specific ocular diseases and ocular surgery experience, the relative legibility of 0.8, 1.0, 1.25 row of vision according to type of target in 7 types of chart were compared. After then we compared by measuring the corrected visual acuity according to type of target by using binocular MPMVA test (#7A) in 60 myopic subjects. Results: In 3 types of target the worst relative legibility target was 'Landolt ring target' with legible distance of 98.97±4.57 cm and the best relative legibility target was 'alphabet target' with legible distance of 108.42±3.46 cm. There was no difference of the relative legibility according to type of chart or visual acuity level in the row of vision if other conditions are the same. In 1.0 and 1.25 row of vision the difference of relative legibility according to type of target was shown the statistically significant difference between 'Landolt ring target' and 'alphabet target' as −0.07±0.06 (p=0.02) and −0.06±0.06 (p=0.04) respectively. In myopia the difference of corrected visual acuity according to type of target was statistically significant difference between 'Landolt ring target' and 'arabic number target' as −0.04±0.02 (p=0.02) and it was especially remarkable in the low myopia. Conclusions: Measuring visual acuity with different optotypes could cause the errors in best vision measurement value because there was difference of the relative legibility according to type of target even though visual acuity level is same in the row of vision.