Contamination of open eye drop bottles occurs at bottle tip, study shows

CHICAGO — Multiuse eye drop bottles appear more likely to be contaminated at the tip of the bottle, as opposed to within the solution itself, according to study results presented here at the American Society of Cataract and Refractive Surgery annual meeting.

Gerald W. Zaidman

"Twenty-three percent of the multiuse open eye drop bottles sitting around in our various offices had positive cultures," Gerald W. Zaidman, MD, said.

Dr. Zaidman and colleagues tested 47 open and previously used multiuse eye drop bottles for contamination. Glaucoma, anesthetic, anti-inflammatory, dilating and antibiotic eye drops were included in the study.

All culture plates were incubated for 72 hours, Dr. Zaidman said.

Overall, 11 of the 47 bottles tested positive for bacterial culture. Of those, three were glaucoma drops, two were anesthetic drops, three were anti-inflammatory drops and three were dilating drops.

Seven of the cultures contained Staphylococcus isolates, one contained a Bacillus isolate and three contained more than one isolate, although all were species of Staphylococcus.

"Our study indicates that contamination of the bottle comes from the tip and not the solution. Therefore, it's either coming from the hands and fingers of the physician or the patient or the eyelids or the eyelashes of the patients," Dr. Zaidman said.

"Presumably cleaning the tip should prevent bacterial contamination," he said.