Half-dose vs one-third-dose photodynamic therapy for chronic central serous chorioretinopathy

Purpose: To prospectively compare the effects of half-dose verteporfin (3 mg/m²) photodynamic therapy (1/2 PDT) with those of one-third-dose verteporfin (2 mg/m²) PDT (1/3 PDT) for chronic central serous chorioretinopathy (CSC). Methods: Sixteen eyes of 16 consecutive patients with chronic CSC were enrolled and followed up for a 3-month study period. The first 10 patients received 1/2 PDT and the next 6 patients received 1/3 PDT. The resolution rate of subretinal fluid (SRF) was compared between the two groups. The changes in the choroidal thickness inside and outside the PDT-applied area in both groups were also evaluated. Results: SRF disappeared in all eyes (100%) in the 1/2 PDT group and in two eyes (33%) in the 1/3 PDT group. In the 1/2 PDT group, choroidal thickness inside and outside the PDT-applied area reduced significantly from the baseline (inside, from 387±24 to 325±25 μm; outside, from 292±25 to 249±19 μm; both P=0.005). In the 1/3 PDT group, choroidal thickness decreased in two eyes where SRF disappeared (inside, 87.2 and 90.9% of the baseline; outside, 91.4 and 92.6% of the baseline), but did not change in the other four eyes where SRF remained (inside, 104.1, 100.0, 105.1, and 100.5% of the baseline; outside, 98.9, 103.0, 100.0, and 99.0% of the baseline). Conclusions: 1/2 PDT is more effective than 1/3 PDT in the resolution of SRF for chronic CSC. Decrease in the choroidal thickness after PDT may be related to the resolution of SRF in chronic CSC.