Microbial contamination of hydrophilic contact lenses. Part I: Quantitation of microbes on patient worn-and-handled lenses.

We cultured Soflens (polymacon) contact lenses to determine the number of microorganisms present following normal patient wear and handling just prior to disinfection. Total protein deposited was determined for the companion lens from each patient. A random population of 109 adapted soft contact lens patients participated in the study. Some patients participated more than once, resulting in a total of 196 lenses being cultured and 195 lenses analyzed for total protein. The left lens was cultured immediately. The right lens was extracted at 70 degrees C in sodium hydroxide, and the total protein in the extract determined using a modified Lowry protein assay. The mean protein deposition per lens was 3.4 micrograms (median 2 micrograms per lens; range less than 1 to 78 micrograms/lens). Microorganisms were cultured from 95% of the lenses. The mean bacterial count (in colony forming units per lens) was 2,482 (median: 123; range less than 3 to 150,000). Fungal contamination was found on 11% of the lenses at very low levels (3-9 yeast/lens and 3-18 mold/lens). Statistical analysis found no significant relationship between bacterial bioburden and any of the study parameters, including total protein, lens age, or subjective evaluation of lens cleanliness.