隐形眼镜中接触角检测方案(接触角测量仪)

ATTENSION AN 8 attension APPLICATION NOTE 8 Captive bubble method in contactlens studies This application note illustrates how the Attension Theta OpticalTensiometer and captive bubble method can be utilized in contactlens studies. Introduction Contact lenses are widely used and hydrogel contact lenses arethe most prescribed type of contact lenses around the world.Hydrogel lenses are made from hydrophilic polymers， such aspolyhydroxyethyl. Contact lenses should have certain characteris-tics to avoid discomfort during wear. These include an adequateoxygen permeability， lens motion and surface wettability.A fairlyrecently discovered material for contact lens manufacturing isthe silicone hydrogel，which is suitable for long term use as it hasimproved oxygen delivery on the ocular surface. However， thismaterial has been reported to have reduced wettability com-pared to the other materials used in hydrogel contact lenses.The wettability of a lens is measured of the ability of the lensto support a continuous and rupture-resistant tear film on itssurface. A lens with a limited wettability is uncomfortable andhas a reduced visual performance.Therefore it has been a majorinvestment for the contact lens industry to develop a soft lenssurface that is highly wettable in the ocular environment.Captive bubble method is a very useful tool to examine the ad-vancing and receding contact angle as it is possible to maintainfully hydrated conditions on the lens surface during the experi-ment. This is essential to mimic the real situation properly. InFigure 1 the contact angle of an air bubble in water is obtainedwith the captive bubble method and it is calculated to be 40°. In highly water wetting lenses the contact angle hysteresis iseliminated and both the advancing and receding contact anglesapproach zero. In the captive bubble method the contact angle is measuredby placing a bubble of air onto the lens surface with a capillary while the lens is immersed in a liquid. Preferably the lens shouldbe soaked in liquid for a couple days before the measurementtakes place in order to get the lens fully wet. The conditions inthis experiment should mimic in vivo conditions as well as pos-sible， meaning that the liquid used in the contact angle experi-ments should be close to the real nature of a tear film in the eye.The tear film is composed of surface active components such asmucin and lysozyme. Receding and advancing contact angles are both importantmeasures of contact lens wettability. A receding angle forms asthe water phase moves away from the capillary. This correspondsto the situation when the eyelid is open and the tear film startsrupturing on the lens. The advancing contact angle developsas the water phase moves towards the capillary. This is the casewhen the eyelid closes and the tear film on the lens starts torecover. Figure 1. Air bubble on contact lens surface With captive bubble method contact angles of lenses can bemeasured in different solutions to obtain the most ideal solu-tion that wets the lens best. Some have reported that significantchange can't be seen in whether the solution is pure water or aliquid containing surfactants (like the contact lens solutions onthe market). Also studies of different coatings to improve the lenswettability have been made. Protein coatings have found to besuccessful in improving the wettability of contact lenses. Proteincoatings resist the tear protein adsorption and deposition intothe lens. ( [1] C. Maldonado-Codina and P. B. M o rgan， "n vit r o wa t er wet- tability of silicone hydrogel contact lens determined using sessile drop and captive bubble techniques" Journal of BiomedicalMaterials Research Part A 83A (2007) 496. ) ( [2]L. Cheng， S . J . Muller and C. J. Radke，"Wettability of silicone- hydrogel contact lenses in the preserve of tear-film components" Current Eye Research 2 8 (2004) 93. ) ( [3] M . C. Lin and T. F . Svitova，"C o ntact lenses wettability in vitro： Effect of surface active ingredients"Optometry & Vision Science87 (2010) 440. ) Contact information ( At t ensio n Bi o l in S ci e n t i fi c Tie taja n tie 2FIN - 0 21 30 E s p o o， F i nland ) ( T E L + 35 895 497 3 30 0 FAX +3 5 8 9 54 97 33 3 3 in f o @a t t e ns io n . comwww .a t t e nsio n .c om ) ( A tte ns io n pr odu cts an d s e rvices are p r ovi de d t o cust o m ers a ll over t he wor l d t h r o ugh B ioli n Scienti fi c i n c o - o p erat io n wi t h a h i g hly com pe te n t n e two r k o f D i st r ib u tio n Pa r t n e r s. F o r a l is t o f releva n t c o n t act d e t a il s， p l e a s e v i sit www. at t en si o n . com ) 瑞典百欧林科技有限公司是一家先进科研仪器生产商，在北欧的瑞典，丹麦和芬兰都有主要产品的研发和生产基地。我们为用户提供高科技、高精度的科研设备，可用于表界面、材料科学、生物科学、药物开发与诊断等研究领域。