Microbial contamination of medications used to treat glaucoma

Br J Ophthalmol. 1995 Apr;79(4):376-9. doi: 10.1136/bjo.79.4.376.


Aims: A study was conducted to estimate the frequency of contamination of topical antiglaucoma medications used by asymptomatic patients.

Methods: The drops and the bottle tips of 194 in use topical medications and the conjunctiva from 109 treated glaucoma patients were cultured.

Results: Bacteria were recovered from 55 (28%) medications. The bottle tip was more frequently contaminated than the drops (p = 0.008). Gram positive organisms were cultured from 50 (91%) of 55 contaminated medications. Thirteen patients (12%) had the same microorganism recovered from the conjunctiva and from the contaminated medication. The frequency of contamination of medications increased with increasing duration of use. Bacterial contamination occurred in 19% of eyedrops less than 8 weeks old in contrast with 40% of bottles used for more than 8 weeks.

Conclusion: Our data suggest that ocular medications to treat glaucoma frequently become contaminated with bacteria and that contamination is related to duration of use. We therefore recommend that opened topical antiglaucoma eyedrops should be replaced on a regular basis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Conjunctiva / microbiology
  • Drug Contamination*
  • Female
  • Glaucoma / drug therapy*
  • Gram-Negative Bacteria / isolation & purification
  • Gram-Positive Bacteria / isolation & purification
  • Humans
  • Male
  • Middle Aged
  • Ophthalmic Solutions*
  • Staphylococcus epidermidis / isolation & purification


  • Ophthalmic Solutions