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Follow on Google News | Oxygen Transmission of Contact Lensoxygen permeability testing, which has a direct influence on wearer amenity, is an important index of contact lens. This article deals with the importance, influencing factors and testing method of contact lens oxygen permeability.
1. Requirements of Contact Lens Materials Wearers attach particular importance to the selection of lens material because it adheres to eye cornea directly. With the publicity of advertisement, many wearers go in for lenses of high moisture content in selecting contact lenses. In their eyes, the higher the moisture content, the better the lens quality. In fact, the pursuit of higher moisture content is very wrong in contact lens selection. Wearers should also take secretory volume of tears, working environment and surroundings into account. Actually, oxygen permeability of lenses is the most important index. The discomfort and wearing time mainly depends on lens oxygen permeability. Moreover, higher moisture content and ultra thin being publicized now are also to improve lens oxygen permeability. Oxygen deficit, which is caused by inability of eye cornea to obtain oxygen, is the most common trouble of wearing contact lenses. Originally, cornea breathes by obtaining oxygen from air directly. When contact lens adheres to eyeball surface, oxygen can still transmits through lenses, but the transmitting rate reduces obviously. Newly increased vessel caused by cornea oxygen deficit will appear as red heron and will increase the opportunity of infection of eyes. For that reason, contact lens of higher oxygen transmission should be selected. Oxygen transmission of lenses is related with lens moisture content and lens thickness because oxygen is transmitted by water. However, the pacing factor that influences wearing effect is whether contact lenses match eye cornea. 2. Oxygen Transmission Testing As spoken above, oxygen transmission of contact lens has a direct influence on wearer amenity and will in turn affect the sales condition. That is why oxygen permeability testing attracts particular attention of lens manufacturers. ISO issued special testing standards for the oxygen permeability testing of contact lenses: ISO 9913-1 Optics and optical instruments- ISO 9913-2 is suitable for rigid and non-hydrogel flexible contact lens materials. The testing indexes are oxygen flux-j, oxygen permeability -Dk, oxygen transmissibility- Testing process includes the following steps: purging system, diverge oxygen gas into upper chamber, sensor output become stable (judging whether transmitting achieves equilibrium) 3. Influence of Lenses Suitability on Oxygen Permeability Whether contact lenses are suitable mainly depends on the perfection of suitability. A good pair of contact lenses should matches perfectly with eye cornea. There is a layer of tear existing between them and is constant flowing .The tears bring oxygen to cornea and take off waste substance. In this way, contact lenses will not change the normal physiological condition of eyes and will not impair eye cornea. Otherwise, even if ultra thin lenses of high moisture content will also adhere closely to the cornea. Under this case, oxygen flowing can only be realized relying on moisture content and lens thickness. Of course, no matter what the suitability is, high oxygen permeability is favorable. 4. Conclusion Oxygen permeability of contact lens, which has a direct influence on wearer amenity, is an important index. That is why manufacturers of various contact lenses are trying their best to improve oxygen permeability of contact lenses. At present, the popularization of PGP has obviously influenced market share of traditional flexible contact lenses. The outstanding merit of RGP is high oxygen permeability, which make no oxygen deficit of eye cornea. With RGP, many complications caused by flexible contact lenses can be avoided. Therefore, RGP become known and encouraged by most experts. Further details please feel free to contact Shirley via: TEL: 0086-531-85061080 FAX: 0086-531-85062108 EMAIL: trade2@labthink.cn SKYPE: shirley-labthink MSN: shirleywu_labthink@ More about Labthink(http://www.labthink.cn/ Labthink focusing on the laboratory testing instruments R&D and production and laboratory IT services, is dedicated to provide professional quality control solutions for customers in packaging, food, pharmaceutical, medical, daily chemistry, printing, adhesive, automotive, petrochemistry, bioscience, construction, new energy and other industries. # # # Labthink provide most excellent quality control solutions for pharmaceutical, foodstuff, cosmetics, packaging, printing, adhesive, automotive, petrochemistry, environment, biology, new energy, construction, aviation and electronic industries worldwide. End
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