Microbial Contamination of Eye Drops: A Systematic Review and Meta-analysis.

OBJECTIVES

To profile the array of microbial contaminants of eye drops, both native and non-native to the ocular surface, and associated factors for contamination.

METHODS

Potentially relevant studies were retrieved from major bibliographic databases (PubMed, Scopus, and Web of Science). Data were extracted, and study-specific estimates of the contamination rates of topical ophthalmic solutions were combined using meta-analysis to obtain pooled results.

RESULTS

A total of 33 studies that evaluated the microbial contamination rate in 4600 samples were included in this study. The microbial contamination rate of in-use ophthalmic medications is 10% (95% CI: 6%-17%; PI: 0%-78%, I2 =95.1%). The contamination rate among diagnostic eye drops is 13% (95% CI: 3%-42%; PI: 0%-98%, I2 =95.6%), and the contamination rate among therapeutic eye drops is 10% (95% CI: 6%-17%; PI: 1%-63%, I2 =94.9%). Staphylococcus spp. were the most prevalent gram-positive bacterial contaminants [3.55% (95% CI: 1.52%-8.04%; PI: 0.08%-63.46%), I2 =93.2%], Escherichia coli , the most prevalent gram-negative contaminants [1.02% (95% CI: 0.50%-2.05%; PI: 0.16 to 6.04%), I2 =24.8%], and Aspergillus spp., the most prevalent fungal contaminants [0.88% (95% CI: 0.31%-2.51%; PI: 0.03%-22.05%), I2 =89.9%].

CONCLUSION

There is a high rate of microbial contamination in topical ophthalmic solutions, which has implications for patient safety and the effort to stem avoidable blindness. Similar to injectable medications, we recommend using single-use vials for topical ophthalmic solutions, as opposed to multi-use vials, which are stored for a protracted period of time and used on multiple patients.