ERG records of the rats. ERG was carried out in both eyes and Ten responses to 0.01 and 3.0 cd × s/m2 white light flash (10 μs, 0.1 Hz) from a Ganzfeld integrating sphere were amplified and averaged. A wave (A and B) and b wave (C and D) amplitudes of dark adapted ERG at 12, 15 and 20 days post immunization were analysed and compared between MSC-exo treated group and control group. Values are expressed as the mean ± SD of six rats (12 eyes) per group. *P < 0.05.