Jinfeng Qu, Li Ma, Yardana Kaufman, and Ilyas Washington (Submitted, 2010).Purpose: To determine whether the porphyrin chlorin e6 can safely enhance the electrical response of the rabbit eye to light.

Methods: Electroretinogram (ERG) a- and b-wave amplitudes in response to green, blue, amber, red and deep red test flashes were compared for rabbits before and after administration of chlorin e6. Light and chlorin e6 induced retinal pigment epithelium (RPE) cell toxicity was measured by the firefly luciferase assay in cell cultures. 

Results: After administration of chlorin e6 ERG amplitudes were enhanced, particularly in response to red light. For deep red light, we measured up to a three-fold enhancement in b-wave amplitude. Chlorin and light showed negligible toxicity to RPE cells in culture at concentrations studied.

Conclusions: Chlorin e6 may safely be used to enhance the electrical response of the rabbit eye to light. Given the clinical use of chlorin e6, further studies aimed at answering whether porphyrins can enhance vision in humans are warranted.