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Junko Tsukiyama, Yuko Miyamoto, Masahiko Fukuda, Yoshikazu Shimomura, Hirohiko Miura, Yasuhiro Kiyomatsu, Jiro Tsuchiya; Evaluation of Deformation and Contamination of Soft Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4706.
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© ARVO (1962-2015); The Authors (2016-present)
It is sometimes difficult to observe and evaluate the shape and contamination of Soft Contact Lenses (SCLs). In order to observe these SCL conditions, we designed a device called the "Contact Lens (CL) Image Viewer." This device enables us to observe lens shapes in saline in both vertical and horizontal mode with a CCD recording system. We also developed the "Ring-light Test System" to evaluate slight distortion of lenses. Contamination can be observed more precisely by a microscope under both dark and bright field conditions. We evaluated CLs from wearers who had complained about poor vision, irritation and poor comfort. Using conventional methods (slit lamp observation and bright field microscopy), it was difficult to find hidden defects, so we made observation with new devices.
We collected some CLs which wearers had complained about, and then made horizontal observations of their shapes with the CL Image Viewer and vertical observations with the Ring-light Test System which shows partial distortions more clearly. Contamination was observed using dark and bright field microscopy.
It is difficult to evaluate lens deformation because lenses in contact with air deform naturally. The CL image viewer enables us to precisely observe slight lens deformation from a horizontal viewpoint when the lenses are in a saline solution. The Ring -light Test System was effective in finding uneven shapes such as small or partial distortions. Bright field observation facilitates the observation of chromatic contamination such as that caused by cosmetics. However, colorless contamination caused by lipophilic substances including lipids and cleansing oils on SCLs was difficult to detect by only using bright field microscopy. Dark field microscopy made the contamination apparent because dark field microscopy emphasizes the contrast of transparent contamination without staining.
We found these methods very useful for the evaluation of deformation and contamination of SCLs. The CL Image Viewer was effective for evaluating the shapes of SCLs and any deformation which had occurred. The Ring-light Test System was able to detect slight and partial distortions of SCLs. The combination of dark and bright field microscopy made it possible to detect contamination of SCLs.
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