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DISCUSSION
Acanthamoeba keratitis is a severe sightthreatening corneal disease. No specific treatment is available clinically. Corneal transplants always needed to restore vision [3]. For the past few years, with the increase of the number of people who wear contact lens, the number of the reports of this disease had a sharp increase. Apart from doing active study in the diagnose and therapy, prevention methods should be strengthened to weaken its threaten to the corneal healthy of human.
Wearing contact lens, corneal abrasion and using polluted water are chief risk factors of this disease [4]. In the developed countries, about 71% to 85% of Acanthamoeba keratitis were concerned with wearing contact lens. It was also reported that contact lens could be a larvate carrier of Acanthamoeba castellanii. In our country, about 33% of Acanthamoeba keratitis were concerned with wearing contact lens [5]. Pollution of contact lens and care solutions caused by bad health habit, decreasing of local immunity caused by wearing contact lens for a long term and failing to clean the adherent proteinum which is beneficial for Acanthamoeba to adhere to the contact lens are the three main reasons of Acanthamoeba keratitis related with contact lens [6]. So, superordinary function of contact lens solutions to degerm and depurate is the foundation to insure its healthy wearing and is an important precautionary measure aiming directly at Acanthamoeba keratitis.
Six kinds of contact lens solutions sold in the market were used in our experiment. According to the using methods of corneal contact lens, 8 hours were set as the observation time to inspect the killing ability of care solutions to Acanthamoeba within their nursing time. Contact lens solutions with arilin added in as combined group were also set simultaneously to observe the killing ability of the combination of care solutions and arilin. The results displayed that the average killing rate of contact lens solutions was 63.2%. Continued cultivation showed that after being dealt in care solutions for 8 hours, most of acanthamoeba were killed and the survivals were turned into cyst with a lower reproductive activity, at least in one cultivation cycle.
As the indispensable medicine for amebiasis, arilin can also be used in the Acanthamoeba keratitis [7, 8]. Now, it is believed that the mitochondria of Acanthamoeba castellanii is insufficient, so it cannot produce enough ATP. But a organelle named hydrogen soma located in the polypide membrane can turn pyruvic acid into acetyl coenzyme A. This structure cannot deoxidize pyrimidine nucleotide, but can transfer the electron of pyruvic acid to the nitro of some medicine like arilin to form poisonous deoxidation product. The latter can bind with DNA and protein to perform its selective toxicity. In our experiment, the average killing rate of the combination of arilin gutta and care solution was 92.4% within 8 hours. So this mixed liquor could play an important role in the precaution of Acanthamoeba keratitis.
More and more attention has being paid to the barrier function of contact lens solutions in the precaution of Acanthamoeba keratitis. Thererfore, the relevant institution should elevate the quality of contact lens solutions to protect the corneal health of all the people wearing contact lens.
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