목적: 본 연구에서는스마트폰을 이용한 근거리 작업 시 조절 기능의 변화가 유도되는가를 알아보고자 하였다. 방법: 20대의 총 63명 (남성 26명, 여성 37명)을 대상으로 조절 기능과 교정 전 등가구면도수를 측정하여 대조군 값으로 하였다. 실내조명 아래에서 연구대상자들에게 30분 동안 책을 읽게 한 후 30분간의 휴식 시간을 가지게 하고 순차적으로 동일한 시간 동안 스마트폰으로 영화를 보게 하거나 작업순서에 따른 오차를 배제하기 위하여 반대의 순서로 영화보기와 책읽기를 하게 하였다. 연구대상자들의 조절기능은 1) 최대조절력, 2) 조절 용이성, 3) 양성 및 음성상대조절, 4) 조절 래그 및 교정하지 않은 등가구면도수를 각 작업 후에 다시 검사하고 대조군 값과 비교하였다. 결과: 단안 최대조절력은 독서 후와 비교하여 스마트폰 시청 후 유의하게 감소하였다. 단안 및 양안 조절용이성은 독서나 스마트폰 사용 후 모두 감소하는 경향을 보였으나 통계적으로 유의한 차이는 아니었으며, 양성상대조절값은 독서나 스마트폰 사용 후 모두 유의한 변화가 없었다. 스마트폰 사용 후 음성상대조절 값은 독서 후와는 달리 거의 변화가 없었다. 스마트폰 사용 후 조절래그 값은 독서 후의 경우보다 유의하게 높았다. 결론: 30분 동안의 스마트폰을 사용한 근거리 작업은 일부 조절기능의 변화를 유발하였으며, 그 변화는 동일한 작업 환경에서의 독서 시 보다 유의하게 컸다.
목적: 본 연구에서는스마트폰을 이용한 근거리 작업 시 조절 기능의 변화가 유도되는가를 알아보고자 하였다. 방법: 20대의 총 63명 (남성 26명, 여성 37명)을 대상으로 조절 기능과 교정 전 등가구면도수를 측정하여 대조군 값으로 하였다. 실내조명 아래에서 연구대상자들에게 30분 동안 책을 읽게 한 후 30분간의 휴식 시간을 가지게 하고 순차적으로 동일한 시간 동안 스마트폰으로 영화를 보게 하거나 작업순서에 따른 오차를 배제하기 위하여 반대의 순서로 영화보기와 책읽기를 하게 하였다. 연구대상자들의 조절기능은 1) 최대조절력, 2) 조절 용이성, 3) 양성 및 음성상대조절, 4) 조절 래그 및 교정하지 않은 등가구면도수를 각 작업 후에 다시 검사하고 대조군 값과 비교하였다. 결과: 단안 최대조절력은 독서 후와 비교하여 스마트폰 시청 후 유의하게 감소하였다. 단안 및 양안 조절용이성은 독서나 스마트폰 사용 후 모두 감소하는 경향을 보였으나 통계적으로 유의한 차이는 아니었으며, 양성상대조절값은 독서나 스마트폰 사용 후 모두 유의한 변화가 없었다. 스마트폰 사용 후 음성상대조절 값은 독서 후와는 달리 거의 변화가 없었다. 스마트폰 사용 후 조절래그 값은 독서 후의 경우보다 유의하게 높았다. 결론: 30분 동안의 스마트폰을 사용한 근거리 작업은 일부 조절기능의 변화를 유발하였으며, 그 변화는 동일한 작업 환경에서의 독서 시 보다 유의하게 컸다.
Purpose: The present study was conducted to investigate whether near work with smartphone could induce the change of accommodative function. Methods: Total 63 subjects(26 male and 37 female) in their 20s were firstly examined their visual functions related to accommodation and uncorrected spherical ...
Purpose: The present study was conducted to investigate whether near work with smartphone could induce the change of accommodative function. Methods: Total 63 subjects(26 male and 37 female) in their 20s were firstly examined their visual functions related to accommodation and uncorrected spherical equivalent power as the control. After that, the subjects were asked to read a book for 30 min and sequentially watch a movie on smartphone for the same time after 30 min-break under the indoor light or as it was in the reverse order to avoid time-ordered effect. Their accommodative functions, 1) accommodative amplitude, 2) accommodative facility, 3) relative positive/negative accommodation, and 4) accommodative lag and their uncorrected spherical equivalent power were examined again following each task and compared with the control values. Results: The monocular accommodative amplitude was significantly decreased after smartphone watching compared with it after reading. The monocular and binocular accommodative facilities were tended to reduce after smartphone watching and book reading but were not significantly different. Neither significant change in positive relative accommodation was determined after smartphone watching nor book reading. Negative relative accommodation after smartphone watching was almost unchanged unlike reading a book. The accommodative lag after smartphone work was significantly higher than after book reading. Conclusions: The near work with a smartphone for 30 min induced the change of some accommodative functions, which was significantly greater than when reading under the same working environment.
Purpose: The present study was conducted to investigate whether near work with smartphone could induce the change of accommodative function. Methods: Total 63 subjects(26 male and 37 female) in their 20s were firstly examined their visual functions related to accommodation and uncorrected spherical equivalent power as the control. After that, the subjects were asked to read a book for 30 min and sequentially watch a movie on smartphone for the same time after 30 min-break under the indoor light or as it was in the reverse order to avoid time-ordered effect. Their accommodative functions, 1) accommodative amplitude, 2) accommodative facility, 3) relative positive/negative accommodation, and 4) accommodative lag and their uncorrected spherical equivalent power were examined again following each task and compared with the control values. Results: The monocular accommodative amplitude was significantly decreased after smartphone watching compared with it after reading. The monocular and binocular accommodative facilities were tended to reduce after smartphone watching and book reading but were not significantly different. Neither significant change in positive relative accommodation was determined after smartphone watching nor book reading. Negative relative accommodation after smartphone watching was almost unchanged unlike reading a book. The accommodative lag after smartphone work was significantly higher than after book reading. Conclusions: The near work with a smartphone for 30 min induced the change of some accommodative functions, which was significantly greater than when reading under the same working environment.
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문제 정의
Only the study related to visual acuity and refractive error after smartphone use were conducted by the other research groups.[15,16]Thus, the present study was conducted to investigate how smartphone use affects accommodation. Accordingly, changes in accommodative function after sustained smartphone work were compared with those induced by near work with reading a book for the same period.
가설 설정
00 D was placed to suppress some possible over-accommodation in front of the subject’s eyes. The subject was asked to state which lines were darker or more distinct. The addition was then reduced binocularly in 0.
제안 방법
A cross-cylinder with 0.50 D was placed in the phoropter (JP/RT-600, NIDEK) with the minus axes in the 90 degree position, and the subject viewed a cross-grid chart (white background; Topcon NEAR-POINT CARD NC-3) at a distance of 40 cm from the eyes in a room illuminated with 50 lux. Then, an additional +2.
After each task, the subjects were asked to answer a simple questionnaire to evaluate any subjective symptom noted during reading or watching. Each question was fully explained to ensure understanding.
The uncorrected refractive errors (spherical and cylindrical) of subjects were measured 3 times before each task without cycloplegia by an auto-refractometer (SHIN-NIPPON JP/SR-7000, JAPAN), averaged, and calculated as spherical equivalent diopters. After each task, the subjects were asked to remove the habitual correction with the trial frame and their refractive errors were measured 3 times and compared with the uncorrected spherical equivalent diopter measured before the task to investigate whether some myopic shift occurred.
For examining the subjects with emmetropia and contact lens wear, the trial frame was used as the reference plane. Afterwards, the subjects were asked to do book reading or smartphone use and the accommodative functions listed above were re-examined and compared with the control values. The examinations of visual function were performed in the same 8 × 7 m.
Sixty three subjects were firstly examined their accommodative function as control value and then asked to sequentially conduct a book reading and smartphone use for 30 minutes with the 30 minute-break between two works in a room sized 8 × 7 m.
The difference between the accommodative stimulus and the response was binocularly evaluated by measuring the accommodative lag (AL) using a fused cross-cylinder. AL was initially determined as 0.
The uncorrected refractive errors (spherical and cylindrical) of subjects were measured 3 times before each task without cycloplegia by an auto-refractometer (SHIN-NIPPON JP/SR-7000, JAPAN), averaged, and calculated as spherical equivalent diopters. After each task, the subjects were asked to remove the habitual correction with the trial frame and their refractive errors were measured 3 times and compared with the uncorrected spherical equivalent diopter measured before the task to investigate whether some myopic shift occurred.
When the subjects clearly read a small letter corresponding to 0.7 visual acuity in decimal from a high contrast black and white card at a distance of 40 cm, they were asked to notify to an examiner and invert their flipper to −2.00 D and then to read the letter clearly again.
대상 데이터
Sixty three healthy volunteers aged between 20 and 28 years (male 26, female 37; averaged 22.5±3.7 years) without ocular disease, ocular surgery history, or accommodative dysfunction as evidenced from eye examination by an ophthalmologist were participated into the study from June 2012 to May 2013.
When asked to use a smartphone, the 63 subjects were asked to watch the movie “Iron Man” (SF Film, Paramount Pictures) with subtitles in Korean (font size, 3.5 mm as the height of a Korean letter) for 30 min at a viewing distance of 40 cm (smartphone screen size 10.2 cm in diagonal, resolution of monitor 480 × 800, luminance of monitor 290 cd/m2 ) in the same room illuminated with 370 lux.
데이터처리
Their statistical significance between before and after each task was determined by one-way ANOVA test using GraphPad Prism 5 (GraphPad Software, Inc., San Diego) and if significant (p<0.05), group means were compared by post hoc analysis using Newman-Keuls Multiple Comparison test.
이론/모형
The accommodative amplitude (AA) was determined by the push-up method of Donders. For measuring monocular AA, a small letter (corresponding to decimal visual acuity of 0.
성능/효과
However, NRA values after reading a book showed a somewhat different result, as NRA of the reading group increased significantly from 2.18 ± 0.32 D to 2.36 ± 0.43 D (p<0.05 by one-way ANOVA and Newman-Keuls Multiple Comparison) while NRA values were slightly reduced from 2.18 ± 0.32 D to 2.04 ± 0.58 D after watching a movie on the smartphone (Table 3).
In our study, the subjects had relatively high AA (9.30 ± 1.21 D) when considering their average age, and showed some reduced ability to accommodation of stimuli showing reduced monocular AA and PRA after sustained smartphone watching for 30 min under indoor light.
후속연구
Even though the change of accommodative convergence can be indirectly assumed by the result of relative accommodation, it should be separately examined to determine the visual function during synkinetic eye movement. Thus, further studies about visual functions in binocular viewing such as positive/negative fusional vergences, fusional vergence amplitude, relative vergence and vertical phoria, etc., are necessary to fully understand the correlation between subjective/objective symptoms and effects on visual function caused by use of smartphones for extended periods.
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