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Evaluation of contact lenses by microbial enumeration and protein determination
J T Barr1, W J Lapple, A C Snyder
1College of Optometry, Ohio State University, Columbus.
Abstract:
Contact lenses worn for varying periods of time (from 1 to 48 months) were subjected to microbiological examination by plate counts and protein determination. Seventy percent of the lenses displayed bacterial colony counts below 120 colony-forming units (CFU)/lens, 28 percent were in the range of 140 to 9060 CFU/lens, and one lens was contaminated with greater than 6 x 10(4) CFU/lens. Fungal contaminants were detected in three lens specimens in the range of 220 to 760 CFU/lens. Protein accumulation showed wide variation of up to 1.2 mg of protein per lens. Statistical analysis indicated highly significant associations (p less than 0.001) between the bacterial colony counts obtained with three different media. Some significant associations were found between the protein concentration and bacterial counts. The data did not indicate statistically significant relations between the above variables and either the water content or the length of wear of the contact lenses.
Insights
Microbiological examination of contact lenses revealed significant bacterial and fungal contamination, with protein accumulation varying widely. Contamination levels did not correlate with lens wear duration or water content.
Area of Science:
- Ophthalmology
- Microbiology
- Biomaterials Science
Background:
- Contact lenses are widely used vision correction devices.
- Microbial contamination and protein deposition on contact lenses can pose risks to ocular health.
- Understanding factors influencing lens contamination is crucial for patient safety.
Purpose of the Study:
- To quantitatively assess bacterial and fungal contamination on used contact lenses.
- To determine the extent of protein accumulation on these lenses.
- To investigate potential correlations between microbial load, protein levels, lens water content, and duration of wear.
Main Methods:
- Microbiological examination using plate counts to quantify bacterial and fungal colony-forming units (CFU)/lens.
- Protein determination assays to measure protein accumulation per lens.
- Statistical analysis to identify significant associations between microbial counts, protein levels, water content, and wear duration.
Main Results:
- Seventy percent of lenses had <120 CFU/lens; 28% had 140-9060 CFU/lens; one lens had >6x10^4 CFU/lens.
- Fungal contaminants were found in 3 specimens (220-760 CFU/lens).
- Protein accumulation varied up to 1.2 mg/lens; significant correlations existed between bacterial counts across different media and between protein and bacterial counts.
Conclusions:
- Used contact lenses frequently harbor significant bacterial and fungal contamination.
- Protein accumulation is a common finding, with levels varying considerably.
- Neither lens water content nor duration of wear showed statistically significant relationships with microbial contamination or protein levels in this study.