• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.253-260
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• 2014

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.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.1
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• pp.27-35
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• 2013

Purpose: The present study was conducted to investigate the changes in the physical properties of RGP lenses induced by the polishing during the process of RGP lens manufacturing, and further evaluate the differences in the actual wearer's comfort and the tear film break-up time caused by these changes. Methods: RGP lenses (fluorosilicone acrylate material) were divided into 4 groups by the different lens-polishing time like 0, 25, 50 and 100 seconds and the thickness, the surface roughness and the wetting angle of those lenses were compared. Furthermore, the comfortability of the lens wear was surveyed after applying these lenses on the subject's eyes with normal tear volume and the non-invasive tear break-up time of the wearers was measured. Results: The central thickness of 4 RGP lenses made of different lens-polishing time was not significantly different however, the lens surface was changed smoother after polishing to be confirmed by scanning electron microscopy. The wetting angle of the RGP lens significantly decreased in accordance with the increase of polishing time. Thus, the difference of approximately $16^{\circ}$ between 0 second and 100 seconds-polishing was statistically significant. The actual wearing feeling of RGP lens was tended to improve in accordance with the increase of the lens wettability however, it was not proportional improvement. The non-invasive tear break-up time of the lens wearers showed different aspect compared with the changes in lens wettability and the actual feeling of RGP lens wear. Conclusions: In this study, better lens wettability, thinner lens thickness, and/or improved lens surface induced by physical stimuli in the process of RGP lens manufacturing was not well-correlated with the increase of actual subjective/objective satisfaction in RGP lens wear. Thus, the consideration of physical properties of the lens as well as the lens wearers' physiological factors in the process of RGP lens manufacturing may be suggested.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.2
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• pp.157-163
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• 2013

Purpose: This study was investigated weather watching 2D and 3D images effecting on accommodative function (AF), and differences between changes of AF by 2D and 3D. Methods: 50 subjects (male 30, female 20) aged 20's to 40's years old ($22.9{\pm}3.93$ years) who are available to watching 3D images were participated for this study. Accommodative amplitude (AA) by near point of accommodation (NPA), accommodative response (AR), positive and negative relative accommodation (PRA, NRA), accommodative facility (AF) were measured before, after watching 2D and 3D images at 1 m distance for 30 minutes respectively. Results: Accommodative amplitude after both watching 2D and 3D images decreased comparing to before watching images, and AA after watching 3D images was significantly lower than after watching 2D images. AR after both watching 2D and 3D images increased comparing to before watching images, but there was no difference between 2D and 3D. PRA and NRA were not significantly different between before, after watching 2D and 3D images. Accommodation speed by AF was increased for before watching ($13.52{\pm}3.32$ cpm) following by for after watching 2D images ($14.28{\pm}3.21$ cpm) and for watching 3D images ($14.90{\pm}3.27$ cpm). Conclusions: Watching images at close distance is effect to accommodation functions, and sequence of AA decrease of before watching images following by after watching 2D images and after watching 3D images may effect to asthenopia with same sequence as AA decrease. The results of increase of AF after watching images, specially 3D images show a possibility of vision therapy and further detail VT studies using 3D images are required in the future.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.3
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• pp.305-309
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• 2012

Purpose:This study was conducted to research any effect on aided distance visual acuity and refractive error changes by using smartphone at near for long term. Methods: 20($20.6{\pm}0.9$ years) young adults subjects with no ocular diseases, over 0.8 of aided distance visual acuity, normal amplitude of accommodation and normal accommodative facility agreed to participate in this study. The subjects were divided into two group, Group 1 (15 cm fixation distance) included 10 subjects and Group 2(40 cm fixation distance) included 10 subjects. Aided distance visual acuity and refractive error were measured before and after using smartphone for 30 minutes by auto-chart project (CP-1000, Dongyang, Korea), phoropter (VT-20, Dongyang, Korea), auto refractor-keratometer (MRK-3100, Huvitz, Korea). After then, the subjects looked at distance with wearing spectacles. Refractive error was measured at 5 minutes, 10 minutes, and 15 minutes later, respectively. Results: After using smartphone at 15 cm for 30 minutes, there was statistically significant reduction of aided distance visual acuity (p=0.030) and increasing myopia (p=0.001). The increased myopia was not statistically significant after 5 minutes rest (p${\geq}$0.464). However there was no statistically significant changes in aided distance visual acuity (p=0.163) and refractive error (p=0.077) after using smartphone at 40 cm for 30 minutes. Conclusions: It is recommend to keep 40 cm off the smartphone from eyes to avoid any aided distance visual acuity and refractive error changes. If smartphone is used closer than 40 cm, a rest for 5 minutes is also recommend after every 30 minutes use with smartphone to avoid any aided distance visual acuity and refractive error changes.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.3
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• pp.249-254
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• 2012

Purpose: To investigate amount of myopic progression with increase of age for children myopes among patients of a Korean optometry clinic. Methods: It has followed up 99 children subjects (male 55, female 44) who had no ocular disease and have visited a Korean optometric clinic for mean $33{\pm}8$ months (13 to 54 months) since June of 2001. Mean age of subjects at first visit was $118{\pm}23$months. Non-cycloplegic refractive error were measured 6 times using Canon RK-3(Japan) every mean 6 months. Results: For all subjects mean of refractive errors increased -0.78 D per year from $-2.02{\pm}1.05D$ at first visit to $-4.18{\pm}1.30D$ at final visit with longitudinal study, but -0.19 D per year with cross-section study, which showed a big difference between two methods. Mean of astigmatic refractive error increased -0.15 D per year. As progression of refractive error according to ages at first visit, refractive errors increased -1.04 D per year for 6 years old, -0.9 D for 7 years old, -0.89 D for 8 years old, -0.89 D for 9 years old, -0.74 D for 10 years old, -0.74 D for 11 years old and -0.72 D for 12 years old. And it showed a tendency that the younger age was the higher progression of myopia. However it was not significantly different between each groups. Conclusions: Follow-up results for myopic children among patients of a Korean optometry clinic showed increase of -0.78 D for myopic refractive error and -0.14 D for astigmatic refractive error per year.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.51-57
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• 2014

Purpose: The present study was conducted to establish the experimental condition for the proper evaluation of protein removal efficacy when developing protein removal agents. Its protein removal efficacy was further analyzed and compared with the result from protein removal efficacy against protein deposition on contact lens to suggest the evaluation method for efficacy of protein removal agents. Methods: Protein digestibility assay presented in the Korean pharmacopoeia was selected to establish the evaluation method for efficacy of papain, pancreatin, subtilisin A and protease itself as a ingredient and protein removal tablets or solution containing those enzymes and find a suitable test conditions. Furthermore, the cleaning efficacy of commercially available protein removal tablets and solution on balafilcon A lens deposited with protein artificially was measured and the correlation between two evaluation methods was further analyzed. Results: When pancreatin itself and the product containing pancreatin was evaluated by protein digestibility assay, both reached 28 IU/mg, the standard value of protein digestibility suggested by the Korean pharmacopoeia. In case of protease and subtilisin A tested with trichloroacetic acid B solution, both of them met the enzyme activity level proposed by the manufacturers when they were evaluated by protein digestibility assay however, papain and subtilisin A tested with trichloroacetic acid A solution were not reached the enzyme activity level. Among protein removal agents, three products except a product containing pancreatin did not meet the enzyme activity value specified by the manufacturer when they were evaluated by protein digestibility assay. However, actual protein removal efficacy of three products except a papain-containing product on the lens was greater than 90% protein removal. In the case of papain-containing protein removal product, its effect was not measured by protein digestibility assay however, its actual protein removal efficacy on the lens reached 73.72%. Conclusions: From the results, it was confirmed that the efficacy of protein removal agents for contact lens should be evaluated by different method according to the type of proteolytic enzyme contained. That is, the protein removal agents containing pancreatin, protease and subtilisin A can be evaluated by protein digestibility assay and protein removal efficiency evaluation and the products containing papain can be effectively evaluated by only the evaluation method for protein removal efficiency employing the lens.

• The Korean Journal of Vision Science
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• v.20 no.4
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• pp.553-560
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• 2018

Purpose : To investigate a disposal method of disposing contact lenses and the recognition of environmental pollution by micro plastics which may be caused by the wrong disposal method of domestic contact lens wearers. Methods : Two hundred sixty one adults(124 males, 137 females, mean age $21.48{\pm}3.14years$) were participated in this study. They were given the questionnaire survey on contact lenses purchasing place, type of contact lenses, duration of wearing contact lenses, the disposal method of disposing contact lenses and the recognition of the occurrence of environmental pollution. Results : It appeared that eyeglass shop(50.0%) and contact lens shop(48.3%) were the main purchasing places, and the most common type of contact lenses were disposable lenses(38.5%) and daily wearing lenses(52.5%). On the duration of wearing contact lenses they answered more than 5 years(29.3%), less than 1 year (26.0%), less than 1 year to less than 3 years (26.0%), and on wearing a contact lens during a week they did 1-2 days (32.0%), 1 week (28.0%), 5-6 days (22.4%) and 3-4 days (17.6%). It was shown "no(78.3%)" and "yes(21.7%)" to the questionnaire of whether they received information or education about a disposal method at the place where the contact lens was purchased, and "no(87.5%)" and "yes(12.5%)" to the questionnaire of whether they received information or education from schools, public institutions or public media such as the internet. As for the disposal methods, landfill waste(45.6%), recycled garbage(29.6%), and drainage(16.8%) from the sink or toilet responded in order. Although men were more educated and informed about disposal than women (t=3.63189, p<0.00001), women were more aware of environmental pollution(t=2.44269, p=0.01605). Conclusion : In order to reduce the environmental pollution issue caused by the contact lens which does not decompose at the sewage treatment facility and become micro plastics, it is urgent to provide information about correct disposal methods after using contact lenses and to educate contact lens wearers.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.171-177
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• 2014

Purpose: The present study was conducted to investigate whether the elution of the dyes from the circle contact lenses existed or not when rubbed with cotton swab. Methods: The change of lens surface was observed by scanning electron microscope when a total of seven kinds of circle contact lens were rubbed with cotton swab, and the dye elution was further compared when the lenses were soaked in multi-purpose solution in $20^{\circ}C$ and $36.5^{\circ}C$ for a week. Results: Five of a total of 7 circle contact lenses showed the dye elution from the front or the back surface of the lens when rubbed with cotton swabs, and existence of dye elution was varied depending on the type of contact lenses and different at the front and back surface even in the same lens. The tear-off of the pigmented portion by the rubbing was found through scanning electron microscopic observation when the dye elution existed. However, the dye was not eluted when the circle contact lenses was soaked in a multi-purpose solution in $20^{\circ}C$ or $36.5^{\circ}C$ for a week. Ingredient of colorant was not provided by the manufacturers in more than 50% of the circle contact lenses investigated for this study and the basic information such as the pigmentation method was provided inappropriately. Conclusions: In this study, the result was the dye elution from circle contact lenses was obtained when a physical force is applied thus, it may appear to contribute the development of circle contact lenses and safety of lens wear.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.1
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• pp.19-25
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• 2013

Purpose: The degree of the pupil covered with tinted region of circle soft contact lens was determined according to the illuminant conditions in everyday life and the change of visual acuity by its covering was further investigated. Methods: The circle contact lens having the non-tinted area of 6.2 mm in the center of the lens was applied on 82 eyes in their 20s and their minimum separable visual acuity and minimum legible visual acuity were determined under the luminances of 50 and 370 lux. Results: The covering of pupil was not found when wearing circle contact lens under 370 lux, however, some pupil covering ranged from 0.40 to 1.70 mm was observed in all subjects under 50 lux. The minimum separable visual acuity and minimum legible visual acuity were significantly decreased by the wearing of circle contact lens under 50 lux and the correlation between the larger pupil size of subjects and more decrease of visual acuity was observed. Furthermore, the decrease of minimum separable visual acuity was larger than the case of minimum legible visual acuity indicating that minimum separable visual acuity was largely affected by the covering of pupil. Conclusions: The consideration is necessary for the lens wearers and the manufacturers since the wearing circle contact lens in low-light indoor or nighttime activities may affect directly visual acuity.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.1
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• pp.77-81
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• 2016

Purpose: This study was performed to investigate the difference of meridional visual acuity and the loss of corrected visual acuity (VA) in order to emphasis the importance of astigmatic correction. Methods: 64 subjects (122 eyes) aged $22.75{\pm}2.36years$ participated in this study. After full correction of astigmatic refractive error, VA was measured in which the direction of the slit filter was matched with astigmatic axis and $90^{\circ}$ to the astigmatic axis. Results: 52 eyes showed no difference in VA between the two direction. However 70 eyes had difference VA between them. 14 out of 52 eyes and 24 out of 70 eyes had under 1.0 in monocular VA. The astigmatic degree was higher in the existence of VA difference between the two direction than non-existence. The difference is higher with under 1.0 monocular VA. Monocular VA is closely related to the focal line having better VA in the principal focal line. Glasses replacement period was analyzed as 6~12 months for the preservation of better VA. Conclusions: The final glasses prescription has to be given with full correction because continued under-correction for astigmatism causes meridional VA difference.