Effect of aspirin therapy on photodynamic therapy with verteporfin for choroidal neovascularization

Photodynamic therapy (PDT) with verteporfin is used for treatment of choroidal neovascularization in several conditions. Platelet aggregation is one of the mechanisms by which PDT is thought to work. This study sought to examine the hypothesis that systemic use of aspirin, an inhibitor of platelet aggregation, affects the efficacy of PDT.

A retrospective review was conducted of data for patients treated with PDT at one institution between 2001 and 2004. End points included total number of PDT treatments, mean time between PDT treatments, change in visual acuity from baseline to 3 months after last PDT treatment, and concurrent or subsequent treatments other than PDT.

A total of 244 eyes of 222 patients met inclusion criteria, of which 102 eyes from 92 patients were included in the aspirin taking group. Aspirin takers received an average of 3.11 PDT treatments compared with 2.39 PDT treatments for nonaspirin takers (P = 0.001). Decrease in logMAR visual acuity was greater for aspirin takers (P = 0.0003), and a loss of > or =3 lines was seen in 58% of aspirin takers compared with 35% of nonaspirin takers (P = 0.0003). These differences remained statistically significant after controlling for patient age, lesion type, and lesion size.

Patients taking aspirin required more PDT treatments and had worse visual outcomes than patients not taking aspirin, possibly due to aspirin's ability to inhibit platelet aggregation and thereby diminish the efficacy of PDT.