> My myopia improved about 3 diopters when I spent a few months at high altitude, and took some pregnenolone. I think it's the CO2 balance in the tissues with reduced oxygen pressure, Bohr effect. If you are adapted, the higher altitudes have more effect. The time I noticed the biggest change I was only at 6600 feet altitude, but shorter stays at 8700 feet caused quick improvement. I used that method for several years and stopped the progression while I did it, but when I started to read all day year after year, I neglected it. I got it from Aldous Huxley's Art of Seeing, describing the Bates method. I worked with an optometrist who had studied at Ohio State, when their optometry school was progressive. [Source](https://lowtoxinforum.com/threads/ray-peat-email-advice-depository.1035/post-230414) > [On light sensitivity and night blindness] Having liver and shellfish once a week to help with the vitamins and trace minerals, and two quarts of milk per day, and plenty of fruit, should help with the sensitivity and night blindness. [Source](https://lowtoxinforum.com/threads/ray-peat-email-advice-depository.1035/post-230414)