To investigate the safe, effective light dose for photodynamic therapy (PDT) in the treatment of chronic central serous chorioretinopathy (CSC).

Thirty-eight eyes of 37 patients with chronic CSC were recruited for this study. From November 2009 to July 2010 and from April 2011 to February 2012, PDT was performed using 50% and 25% of the full light dose in 27 eyes of 27 patients (group I) and 11 eyes of 10 patients (group II), respectively. The minimum follow-up period was 6 months. Mean change in best corrected visual acuity (BCVA) and central retinal thickness, hyperpermeability change from abnormal choriocapillaris, success rate, recurrence rate, and complications were analyzed.

Group I showed that BCVA (log MAR) improved significantly from 0.33 ± 0.17 to 0.14 ± 0.15 at 6 months ( p < 0.001). However, there was no significant improvement of BCVA ( p = 0.050) in group II. One eye out of 27 eyes (3.7%) in group I and 5 eyes out of 11 eyes (45.5%) in group II showed recurrence at the 6-month follow-up ( p = 0.016). After initial PDT, hyperpermeability from abnormal choriocapillaris reduced or disappeared at 95.5% in group I and 54.5% in group II at month 3 ( p = 0.016). No patient in either group experienced severe adverse events.

PDT performed with 50% of the full light dose appears to be a more useful method in the treatment of chronic CSC, with less frequent recurrence, than PDT using 25% of the full light dose.