RESUMO
BACKGROUND: Intraocular contract lens (ICL) implantation emerges as a crystal refrangibilit operation to rectify and cure high myopia in recent years. Collagen, a new material, is consisted of collagen Ⅳ and aquagel in Starr Company. It is an ideal material for ICL; however, high price is restricted to its development at a certain degree.OBJECTIVE: To find out ideal method of collagen ICL implantation through animal experiment in rabbit eyes and evaluate intraocular biocompatibility by observing inflammatory reaction and variation of inflammatory mediators.DESIGN: Single exponent and opening study.SETTING: Department of Ophthalmology, Xinhua Hospital affiliated to Medical College of Shanghai Jiaotong University.MATERIALS: The experiment was carried out in Xinhua Hospital affiliated to Medical College of Shanghai Jiaotong University and Shanghai Nanyang Radio-immunity Testing Center from August 1999 to March 2000.Twenty New Zealand rabbits were divided into three groups according to randomly digital table: ICL implantation group (n=8), operative control group (n=6) and blank control group (n=6).METHODS: ① Right eyes of rabbits in ICL implantation group were suffered from ICL implantation and peripheral operation of iris [1]; however,right eyes of rabbits in operative control group were only suffered from peripheral operation of iris. After operation, hormone-antibioltic eyedrops were dribbled into eyes four times a day for total 10 days. At 1, 4 and 7days after operation, 2.5 mg dexasone + 40 000 U cidomycin were subconjunctivally injected into eyes. Rabbits in black control group did not receive any operation. ② At 1, 4, 7, 14 days and 1 month after operation,indexes of operative eyes in ICL implantation group and operative control group were measured including luctuation of intraocular pressure, damage of corneal endothelium, protein leakage in anterior chamber, depth of anterior chamber, hyphema, posterior synechiae of iris, ICL decentration and lens opacity. ③ At 1, 4, 7, 14 days and 1 month, samples of aqueous humor were aspirated from operative eyes of rabbits in ICL implantation group, operative control group and blank control group. Radioimmunoassay (RIA) was used to examine the concentration of prostaglandin-E2 (PGE2)in aqueous.MAIN OUTCOME MEASURES: ① Results of reaction in anterior chamber at each time point before and after operation; ② results of PGE2 concentration of inflammatory mediators in aqueous humor after operation.RESULTS: All 20 rabbits were involved in the final analysis. ① Changes of intraocular pressure at each time point before and after operation: As compared with that before operation, intraocular pressure was not changed in ICL implantation group and operative control group at each time point after operation (P ＞ 0.05). ② Damage of corneal endothelium and leakage in anterior chamber after operation: ICL implantation group: Five eyes were shown as shallow anterior chamber at various degrees on the first day after operation, and recovered normally within 1 week; hemorrhage was observed in anterior ch amber of two eyes and absorbed after 2 weeks; two eyes had anterior and posterior synechiae of iris, respectively, and pupil was deformed slightly; ICL decentration at various degrees was observed in two eyes; point-like opacity was observed in anterior bursal membrane of crystal in one eye after 1 month. Operative control group: Leakage of grade 1-2 was observed in 6 eyes on the first day after operation and was absorbed within 1 week. Cornea was clearing, and hyphema, shallow anterior chamber, posterior synechiae of iris and lens opacity were not changed. ③ PGE2 concentration of inflammatory mediators in aqueous humor after operation:PGE2 oncentration was the highest in ICL implantation group at 1-4 days after operation, and then it was decreased gradually; however, PGE2 concentration was similar at 14 days and 1 month after operation (P＞0.05).CONCLUSION: There is no obvious occurrence of chronic uveitis in anterior chamber after ICL implantation. PGE2 concentration in anterior chamber is decreased gradually, and this suggests that a classic foreignbody granulomatous inflammation emerges after ICL implantation, which reflects a good tolerance of ICL for ocular tissue.
RESUMO
BACKGROUND: A new type of materials, Collamer, is polymerized with type V collagen and HEMA by Staar company, which is a good material for the establishment of intraocular contact lens(ICL). There is no similar material in our country.OBJECTIVE: To evaluate the biocompatibility of ICL made mainly by collagen-polymer in animals.DESIGN: A randomized controlled trial.SETTING: Testing Center of Shanghai Institute of Biomaterial.MATERIALS: Our study was conducted in the Testing Center of Shanghai Institute of Biomaterial from January 2000 to April 2000. Cell strain: hearty L-929 cells(fibroblast of mouse) after 48-72 hours of passage; Twenty white guinea pig of either gender aged between 1 month and 3 months with a body mass between 300 g and 500 g; Seven healthy adult New Zealand rabbit of either gender(female rabbits were not required pregnant for pyrogenic reaction test) with a body mass between 1.7 kg and 3.0 kg or between 2.5 kg and 3.5 kg(experimental animals were obtained from Shanghai experimental animal center, ordinary grade).INTERVENTIONS: Collagen was used to perform the following biological tests: ① cytotoxicity test (cell growth rate); ② anaphylaxis test; ③ pyrogenic reactions test; ④ subcutaneous implant test. The data were analyzed and evaluated according to criteria.MAIN OUTCOME MEASURES: ① Growth and proliferation of fibroblast in mice; ② Reactions of erythema and edema of every provocation site and every observatory time after the induction of intradermal injection and local patch test; ③ Increase of body temperature of the rabbit after the injection of the extraction of the material into auricle marginal vein; ④ Reactions around the materials after 4 weeks of collagen implantation in rabbits subcutaneously.RESULTS: ① Cytotoxicity test: relative growth rate of collagen group was 99％ to 106%, and the toxicity grade was level 0 - 1. ② Anaphylaxis test:there was no erythema or edema reaction at every provocation site at each time point of collagen group. The skin reaction to collagen-polymer was level 0. ③ Pyrogenic reactions test: the temperature increased in rabbit was below 0.6 ℃ and the total increase of the temperature was below 1.4 ℃ in rabbits. ④ Subcutaneous implant test: there was very little lymphocyte infiltration around the sample in both collagen group and control group with Level I inflammatory reaction. And the evaluation of the formation of fiber cyst was level I.CONCLUSION: Results of material biological evaluation tests demonstrate that this collagen-polymer has high biocompatibility, and can become an ideal material for ICL.