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KMID : 1011420180230030227
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Journal of Korean Ophthalmic Optics Society
2018 Volume.23 No. 3 p.227 ~ p.239
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Effects of Repeated Temperature Changes on Soft Contact Lens Parameters
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Cho Chang-Kwon
Song Tae-Hwan
Lee Se-Eun
Kim So-Ra
Park Mi-Jung
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Abstract
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Purpose: The present study was conducted to investigate the changes in parameters of soft contact lenses caused by repeat exposure to various temperatures during distribution or storage.
Methods: Intact 4 soft contact lenses made of different materials with or without wetting agent were placed for 4 hours at ?20, 20, 50, and 80oC, and then stabilized at room temperature for additional 20 hours, respectively. This procedure was repeated 1, 3, and 5 time(s), and then refractive power, diameter, base curve, water content, thickness, visible light transmittance, UV transmittance and oxygen permeability of each lens were measured.
Results: Although there were differences in degree in all four types of soft contact lenses, statistically significant changes in lens parameters were observed at ?20oC and 80oC. The overall diameter, water content, base curve and central thickness were increased or decreased in all lenses regardless of temperatures; however, the refractive power showed different pattern of increase/decrease at low and high temperatures indicating that the degree and pattern of change varied according to the lens parameters. Also, the changing pattern of parameters was different at low temperature and high temperature depending on the ionicity of soft lens, the presence of wetting agent, and the presence of silicone hydrogel material.
Conclusions: From the results, the soft lens parameters were revealed to change by exposure to low- or high-temperature environment that may happened during distribution. Since these changes may cause problems with vision correction or comfort, it is necessary to prepare the standard for temperature during lens distribution and pay attention to it.
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KEYWORD
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Soft contact lenses, Parameters, Repetitive temperature changes, Distribution temperature, Material characteristics, Wetting agent
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