How safe are coloured contact lenses illegally sold on street in Thailand?

Abstract

Objectives: To assess the incidence of contamination from bacteria, fungus, and protozoa
in colored contact lenses illegally sold on the street in Thailand and to specify contaminated microbial species by microbial culture in order to generate empiric antimicrobial
guidelines.
Design: cross-sectional study
Methods: This is a cross-sectional study of colored contact lenses illegally sold in street
markets in 50 districts of Bangkok. We had 350 samples of colored contact lenses. All of
the colored contact lens samples underwent microbial culture using broth agar in the laboratory. We evaluated the safety of the samples by observing the number of colored contact
lenses that show positive microbial culture, reported as a percentage of all tested colored
contact lenses. We set an acceptable microbial growth value at 0.5%. If more than 0.5% of
all contact lens samples had positive microbial culture, we considered these contact lenses
contaminated and unsafe. Each positive bacterial growth sample would be confrmed by
subculture and the growing colony was evaluated and identifed by biochemical tests.
Results: The 350 samples of colored contact lenses were from 6 brands: 26 samples
of Barbie contact lens, 81 of Dream Color contact lens, 6 of Eye Berry contact lens, 34
of Kawaii contact lens, 6 of Lollipop contact lens, 8 of Mimi contact lens, 68 of Pretty
Doll contact lens, and 121 of Sweety Plus contact lens. All of the colored contact lenses
were made of Polyhema and immersed in normal saline. We performed microbial culture.
Brain heart infusion broth, which is specifc to growths of gram-positive bacteria, gramnegative bacteria, anaerobic bacteria, fungi, and protozoa
Conclusion: Our study shows no microbial growth in every sample so we can conclude
that colored contact lenses illegally sold on streets in Bangkok are uncontaminated.
Conflicts of interest: None