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KMID : 1011420180230010047
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Journal of Korean Ophthalmic Optics Society
2018 Volume.23 No. 1 p.47 ~ p.56
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The Change of Convergence Function of Convergence Insufficiency in Their Twenties after Doing Near Work Using a Smartphone
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Kim So-Ra
Park Si-Yoon
Yeo Hye-Jeong
Kim Dae-Yeon
Jung Ji-Hye
Jang Hyo-Seon
Shin Jang-Cheol
Park Mi-Jung
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Abstract
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Purpose: In this paper, the change of convergence function of convergence insufficiency in their twenties after doing near work using a smartphone was investigated.
Methods: The subjects in their twenties with corrected or uncorrected binocular visual acuity of 0.8 or better were examined their visual fuctions, and selected as 22 normal (27.60±2.20 years) and 11 convergence insufficiency (CI, 26.53±2.54 years) groups according to their convergence function. Then, near point of convergence (NPC), horizontal phoria, AC/A ratio, negative fusional vergence (NFV), positive fusional vergence (PFV) and subjective symptoms were measured both before and after watching a movie on smartphone for 30 minutes and further analyzed.
Results: NPC tended to recede in normal group after using a smartphone; however, there was no large difference in CI. Far horizontal phoria was significantly shifted toward orthophoric position in both normal and CI groups, and significant difference of near horizontal phoria was only shown in CI group. Significant difference of AC/A ratio after watching a movie was only shown in normal subjects. There was no significant change in both near PFV and NFV of normal and CI groups. In the case of subjective symptoms, the eye related symptom score was significantly increased only in CI group. Subjective symptoms such as eye fatigue, discomfort, somnolence and burning were increased in both groups, and in CI group, blur, loss of concentration and slow down of reading speed were relatively increased compared with those in normal group.
Conclusions: After using a smartphone, the convergence function and asthenopia may change according to whether the convergence function of subjects is normal or not, which can cause blur and loss of concentration. Therefore, the results suggest that working hour should be adjusted according to convergence function.
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KEYWORD
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Smartphone, Convergence insufficiency, Near point of convergence, Phoria, AC/A ratio, Fusional vergence, Subjective symptom
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