April 2011
Volume 52, Issue 14
ARVO Annual Meeting Abstract  |   April 2011
Preservative Exposure and Surgical Outcomes in Glaucoma Patients: The PESO Study
Author Affiliations & Notes
  • Catherine M. Birt
    Ophthal & Vis Sciences, University of Toronto, Toronto, Ontario, Canada
  • Corey Boimer
    Ophthal & Vis Sciences, University of Toronto, Toronto, Ontario, Canada
  • Footnotes
    Commercial Relationships  Catherine M. Birt, Alcon, Allergan, Merck Frosst, Pfizer (C); Corey Boimer, None
  • Footnotes
    Support  CREMS Summer Program 2010
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 613. doi:
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      Catherine M. Birt, Corey Boimer; Preservative Exposure and Surgical Outcomes in Glaucoma Patients: The PESO Study. Invest. Ophthalmol. Vis. Sci. 2011;52(14):613.

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      © ARVO (1962-2015); The Authors (2016-present)

  • Supplements

To study the impact of benzalkonium chloride (BAK) exposure from eye drops on subsequent time to trabeculectomy failure.


Retrospective chart review of 128 glaucoma patients who had undergone a trabeculectomy between 2004 and 2006. The number and type of ophthalmic drops used preoperatively and relevant demographics were recorded. Surgical failure criteria included inadequate pressure lowering or need for postoperative ocular anti-hypertensives, laser trabeculoplasty, 5-FU needling, or repeated surgery. Patients were examined for these criteria over a minimum postoperative period of two years. Data was assessed using Kaplan-Meier and Cox regression models.


Median patient age was 72 (SD 11.7). Average postoperative follow up time was 4.3 years, ranging from 2.0 to 6.3 years. Complete surgical success was achieved in 47.7% of patients. Patients received between one and eight BAK-containing drops daily, with a median of three. Time to surgical failure in patients receiving higher preoperative daily doses of BAK was shorter than in patients who had less BAK exposure (P=0.008). Proportional hazard modelling identified uveitic and neovascular glaucoma as significant confounders of the univariate model (P=0.024), although the main effect of BAK exposure was maintained with a hazard ratio (HR) of 1.21 (P=0.032). The number of different medications used to control intraocular pressure did not significantly affect survival time in a secondary Cox model (P=0.948).


Increased preoperative exposure to ophthalmic solutions preserved with BAK is a risk factor for earlier surgical failure, independent of the number of medications used. This study supports earlier findings of potential adverse effects of ophthalmic preservatives on surgical outcomes and extends those findings to the modern pharmacopeia used in the medical management of glaucoma.  

Keywords: drug toxicity/drug effects • clinical (human) or epidemiologic studies: outcomes/complications 

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