The effect of green tea (Camellia sinensis) on Pseudomonas aeruginosa treated contact lenses.

Mariah Bigaud


Pseudomonas aeruginosa is the leading cause of ocular infections in those who wear contact lenses. Studies have been done using selenium-coated contact lenses to inhibit the growth of the bacteria to provide an opportunity for individuals to wear contact lenses for a prolonged period of time. Selenium has antioxidant properties that kill the bacteria, however, it is toxic even when used in small quantities. Other similar studies have also been successfully done with another antioxidant, black tea, to effectively inhibit P. aeruginosa growth on contact lenses. In this study, green tea, which is a strong antioxidant that is derived from the same plant (Camellia sinensis) as black tea, was used to treat contact lenses. A disc diffusion assay was first done using different concentrations of green tea to study the inhibitory effect on P. aeruginosa and the results were compared to the inhibitory effects of black tea. The results demonstrated that green tea was significantly more effective than black tea in inhibiting the bacteria. The 100 mg/mL of green tea was the most effective concentration that maintained a uniform solution, producing an average of a 2.05 cm diameter of clear zone with 107 CFU of P. aeruginosa. Contact lenses were used and treated with 100 mg/mL of green tea for possible coating before being exposed to 106 CFU of P. aeruginosa. The results showed that green tea treated contact lenses had fewer bacteria, with a 41.9% inhibition rate when compared to the control with no coating, however, the results were not significant. Another experiment was done by exposing contact lenses to 106 CFU of P. aeruginosa first, and then treating them with 100 mg/mL of green tea to determine the bactericidal properties of the tea. The results showed that green tea significantly reduced the bacteria present on contact lenses (p < 0.05). In conclusion, green tea shows an inhibitory effect on Pseudomonas aeruginosa on contact lenses.


Green tea, contact lenses, Pseudomonas aeruginosa

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