Preservative exposure and surgical outcomes in glaucoma patients: The PESO study (Drs Corey Boimer & Catherine Birt)

Corey Boimer, a 3rd year medical student, presented this work as part of the Canadian Glaucoma Society session at the 74th Annual meeting of the Canadian Glaucoma Society. This talk was given at 1048hrs on 10Jun2011 in Vancouver, BC.

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Poison

Generally medical first line therapy but risk early failure from med Tx. Is it the med or preservative that is the culprit? Benzalkonium Chloride (BAK) is a detergent that does cause conjunctival metaplasia. There are altrnatives to BAK such as BDD (the XE formulation used by Merck), SofZia (the -Z formulation for Alcon), Purite (Allergan’s -P for Alphagan-P), and unit dosing (steriles single-use vials.)

The purpose of this study was to identify if BAK causes poorer glaucoma surgical outcomes based on a retrospective review. Patients using miotics and epinephrine were excluded as these drugs themselves are known to cause their own conjunctival problems. The data was collected and they looked for: complete success, qualified success or failures. The main outcome measures were time to failure and number of drops needed to achieve pressure control. There were lots of POAG patients but also PXF and Pigmentary glaucoma patients as well.

Results were 47.7% compete success, 3.1% complete failure. Time to failure was shorter in patients receiving more total drops per day; type of med not associated with failure risk. The Kaplan-Meier survival curve was shown.

Dose response curve with amount of BAK exposure was also presented. Although increased pre-operative exposure to eye drops with BAK was a risk factor for earlier failure of glaucoma surgery, it is independent of the total number of such meds being used.