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KMID : 1011420170220010033
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Journal of Korean Ophthalmic Optics Society
2017 Volume.22 No. 1 p.33 ~ p.40
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The Stability and Safety Evaluations of Soft Contact Lenses past their Expiry Date
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Kim So-Ra
Kim Dong-Jin
Hwang Hye-Won
Park Mi-Jung
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Abstract
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Purpose: Lens shape, variations in function-related parameters, and contamination of soft contact lenses past their expiry date were investigated.
Methods: Two types of soft contact lenses made of different materials were examined. The lenses that were left an expiry date over one year, almost expired, and past their expiry date according to the criteria on usage period specified by manufacturer were investigated. Their total diameter, radius of curvature, central thickness, refractive power, water content, oxygen permeability, visible light and UV transmittance were measured, and the presence of bacteria was further measured according to the criteria about stability and safety of contact lenses proposed by the Ministry of Food and Drug Safety.
Results: There was a statistically significant change in almost expiring narafilcon A lens as well as the narafilcon A lens past its expiry date. That is, total diameter and refractive power of the lenses increased, and central thickness and oxygen permeability of the lenses statistically decreased. In nelfilcon A lens past the expiry date, the decrease in total diameter, radius of curvature, visible light transmittance, and the increase in water content were statistically significant. However, bacterial contamination was not found in all lenses.
Conclusions: In this study, it was revealed that the parameters of soft contact lenses that were nearly expired or past the expiry date changed, and their degree of change varied depending on the lens material. Therefore, it is suggested that the usage period of the soft contact lens should be appropriately determined depending on the material.
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KEYWORD
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Soft contact lens, Expiry date, Parameter stability, Bacterial contamination
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