Photodynamic effects on retinal oxygen saturation, blood flow, and electrophysiological function in patients with neovascular age-related macular degeneration

Purpose: To evaluate the effect of photodynamic therapy (PDT) on retinal functions, such as oxygen saturation, blood flow, and electrophysiological function using Fourier transform-based spectral retinal imaging (SRI), Heidelberg retinal flowmeter (HRF), and multifocal electroretinogram (mfERG). Methods: This was a prospective interventional case series. Twenty-two patients with age-related macular degeneration (AMD) with unilateral choroidal neovascularization (CNV) were examined using SRI, HRF, and mfERG before and 1 week and 1 month after PDT. Eleven fellow eyes without CNV and 11 control eyes of 11 age-matched healthy volunteers were also investigated. Eleven of 22 patients with neovascular AMD were retreated using verteporfin PDT and examined using a protocol similar to the one used for the first treatment. Results: Oxygen saturation levels in the macula of eyes with neovascular AMD were significantly higher than those in normal control eyes (P = 0.026) but were not significantly higher in eyes with nonneovascular AMD. Oxygen saturation levels decreased 1 week after a single treatment (P = 4.59 × 10) and retreatment (P = 0.0134) and recovered to baseline levels at 1 month follow-up (P > 0.05). HRF demonstrated reduced mean blood flow at 1 week after single treatment (P = 9.22 × 10) and retreatment (P = 0.0307). One month after PDT, mean blood flow tended to show recovery. There was a similar decrease in mfERG amplitude 1 week after treatment, but the logarithm of minimum angular resolution (logMAR) vision was stable or improved throughout follow-up. Conclusion: Oxygen saturation levels, mean blood flow, and mfERG amplitude decreased 1 week after PDT treatment in both single treatment and retreatment groups. Although logMAR vision is stable or improved, our data showed transient functional deterioration in the retina after PDT treatment.