Purpose: To investigate the influence of seasonal light intensity and patients' iris color on the visual recovery after anti-vascular endothelial growth factor (VEGF) therapy with ranibizumab or bevacizumab for neovascular age-related macular degeneration (AMD).
Methods: The visual acuity of 555 eyes (529 patients) with neovascular AMD was evaluated after intravitreal injections of either ranibizumab or bevacizumab in respect to global radiation intensity and iris color.
Results: The functional results during anti-VEGF therapy revealed a seasonal oscillation with a negative correlation between visual recovery and global radiation intensity (R(2)=-0.756, P=0.004). Although the influence of the sunlight intensity on the visual recovery was significant after the first injection, this effect vanished within the continuous course of treatment. Regarding the improvement of functional recovery depending on iris color, dark-colored eyes (16.0%) gained 8.5 ± 10.0 letters after the first injection and 9.9 ± 12.8 letters after the second injection, compared with 3.4 ± 8.6 letters and 4.4 ± 11.0 letters in light-colored eyes (84.0%), respectively (P=0.005 and P=0.019).
Conclusions: Our results indicate that seasonal sunlight intensity and iris color might influence the visual recovery of neovascular AMD patients undergoing anti-VEGF therapy. Our findings may be used as suggestions to refine individual anti-VEGF therapy regimens, especially in patients with light-colored eyes.