Optimal Temperature of Enzyme Cleaners and Amino-acid Analysis of Contact Lens Deposits

Kim, Jae Ho; Akaboshi, T

Abstract

There are many contact lenses, of different materials, available in Korean and Japanese markets. Contact lens wearers are increasing in the world but we are facing more problems of the contaminants on the lenses. These contaminants can be classified as either external or internal one. Gas or smoke in the air, ink, iron dust and fungus are examples of a few of the many external contaminants. The wearer can, with proper precaution, prevent these types of materials from soiling his lenses. However, it is the contamination from internal sources, such as tears and other substances which originate in the human body, which cannot be prevented from soiling the lenses. The tear consist of three layers. the outer surface is the lipid layer originating in the Meibomian glands. The middle layer is the aqueous layer which is discharged by the lacrimal glands. The inner layer, called the mucus layer, is discharged mainly by the conjunctival goblet cells. Each of these layers contain organic materials such as mucin, protein and lipid and inorganic materials such as calcium, which cause deposits on the soft contact lens. Because contact lenses float in the aqueous when they are in the eye, it is only natural for them to become contaminated by these materials. These contaminants may decrease visual acuity, spoil comfort, occasionally irritate the eye, cause corneal inflammation, and shorten the lens life. Therefore, care system for cleaning lenses are very important. And soft contact lens deposits and its protein coating in particular represent one of the most common contact lens complications encountered by both contact lens wearers and practitioners. In order to remove these contaminanta, daily cleaners composed mainly of surfactants and weekly cleaners containing enzymes are usually used. Purpose of this study is: (1) To investigate effectiveness of various enzyme cleaners which are marketed in Korea and Japan(Clean-O-Gel II, Bioclen-G, Hydrocare F, Hoya clean, Renewer F, and Hypa Tab.) and to find optimal and inactivated temperature of each products by use of artificial soilant. (2) To find out which of the materials are main component of contaminants which adhere to contact lenses, by amino acids analysis of contaminants found on patient worn soft contact lens(S.C.L.). Experiment 1: Preparation of the artificial soilant and methods: 18.75mg of lysozyme chloride(white of egg, Tokyo Kasei K.K.) was added to 150cc of 1% hydroxyethyl cellulose solution (Showa Kagaku KK 20,000c.p.s.), and the pH was adjusted to 8 with sodium phosphate dibasic 12 hydrate. After stirring for 5 minutes at 80 degrees C lysozyme chloride was denatured and a white turbid liquid was obtained. After cooling this solution 187.5mg of mucin (stomach of pork, SIGMA Chemical) and 187.5mg of albumin of egg white (Kanto Chemical K.K.) and 600 mg of sorbic acid was then added and was dissolved and mixed thoroughly. Further 150mg of distilled water was added and after mixing the solution homogeneously, the complexed soilants were obtained. And each enzyme cleaner was then dissolved in 5ml/tablet of preheated distilled water and the same amount of the artificial soilant solution/tablet was added. Hypa Tab contains insoluble agents as an vehicle, so precipitation was observed and since affects the measurments, it was filtered before adding the soilant solution. Then opacity change of the each solution were observed at 20, 30, 40, 50, 60, 70, 80, 85, 95 degrees C for 4hrs at each temperature in order to study the decompositive strength on soilant. The measurements in transparency change were taken, from 5 min to 4 hrs, after each enzyme cleaners were reacted, with a Hitachi spectrophotometer at 570nm wave length. All the reaction was done in a water bath with thermostat at each temperature range. Experiment 2: Amino acid analysis of lens deposits and methods: Four pieces of uniformly contaminated soft contact lenses from the patients worn were used for this esperiment and amino acid analysis was made by using of Hitachi Liquid Chromatographer TYPE 835(Japan). Each S.C.L. was immersed in a beaker containing 3ml of 0.02 sodium hydrochloride for one night. The next morning the solution was shaken for two hours and then filtered. The pH was adjusted to 3 and the amino acid analyzed by a Hitachi Liquid chromatographer type 835 (Japan). And the results were obtained as follows: 1. Optimal temperature of the most enzyme cleaners was from 50degreeC to 70 degrees C with an exception of a slightly higher temperature above 70 degrees C in an enzyme cleaner. 2. Inactivation temperature for the most enzyme cleaners was 60 degrees C except on enzyme cleaners, Hypa-Tab solution which required 85 degrees C to be inactivated. 3. Activating time of the most enzyme cleaners was between 20~30 minutes but Clean-O-Gell II was activated lately after 3 hours. 4. Consumers usually use an enzymatic cleaner under room temperature (18~20 degrees C), therefore, Bioclen-G, especially, has very minimal difference of strength between 20 degrees C and 30 degrees C and showed very effective within short time at both temperatures. 5. In amino acid analysis of S.C.L deposits, the main components of S.C.L. deposits were possibly a type of mucin and not lysozyme. Also, when comparing the amount of cystein found in blood serum to the amount found in the test, the levels found in the test were about the same or higher. It has been concluded that the cystein coating to S.C.L.'s which were placed in the Hydrocare solution was produced by alkaline decomposition. A large quantity of cystein was detected on the colored specimen used in the Hydrocare solution. And there was a relationship between cystein and S.C.L. discoloration.

Optimal Temperature of Enzyme Cleaners and Amino-acid Analysis of Contact Lens Deposits

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