Purpose To evaluate the effect of half-dose verteporfin photodynamic therapy (hPDT) on the physiology of the macula determined by focal macular electroretinograms (FMERGs) in eyes with chronic central serous chorioretinopathy (CSC). Methods Fourteen eyes of 13 patients with chronic CSC were treated with hPDT. The best-corrected visual acuity (BCVA) was measured, and optical coherence tomography (OCT) and FMERGs were performed at the baseline, and at 4 days, 1, 3, 6, and 12 months after the hPDT. Results The subreitnal fluid was resolved in 12 of the 14 eyes after the hPDT. The amplitude of the a-wave at 12 months was significantly increased by 1.28 times over that at the baseline. The amplitude of the b-wave was also increased but not significantly (P = 0.055). The implicit time of the a-wave was significantly reduced at 6 months, and that of the b-wave at 3 months. The amplitudes of the oscillatory potentials did not change significantly during the 12-month follow-up period. Conclusions hPDT led to an improvement in the FMERGs for at least 12 months without a transient depression of the FMERGs in eyes with chronic CSC. hPDT can be used safely to treat eyes with CSC.