CLOCK and optic papillitis: In the retina from 37 days space flown mice onboard the ISS, for example, a number of genes were differently methylated with spaceflight vs. ground control (sex and age-matched) suggesting that microgravity decelerated the retinal clock at both epigenomic and transcriptomic levels with potential impact on eye-related disorders such as spaceflight-associated neuro-ocular syndrome including optic disc edema, seen among astronauts90.