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I don't buy into Bates really, but a few things have grown out of it that have have been validated over time. For example, minus spherical correction does stimulate rearward axial growth of the eye.
I met an optometrist who has a great reputation for visual therapy for lazy eye, accommodative and convergence dysfunction etc. for kids mostly but also adults, and this was his opinion. Took the astigmatism completely out of my script and reduced my spherical correction. Those were the most comfortable and functional glasses I ever had. Unfortunately I moved too far to do the weekly vision therapy sessions.
As for the sun, the idea here is that there is a hormetic response. A large amount of sun and uv light will just end up giving you the equivalent of a sunburn on your eye. But limited daily exposure you build up some resilience through up-regulation of defensive genes. I don't advocate staring at the sun. Sunglasses are pretty mandatory much of the time due to all of the extra glare caused by pavement and cars. But think of natural environments like forests, clearings with grass, etc that humans evolutionary spent a lot of time in. The only protection you need is a wide-brimmed hat. It's the concrete jungle that makes sunglasses so mandatory. One of the best and scientifically validated examples of hormesis is that many of the benefits of exercise are completely eliminated when antioxidants are taken before or after a workout. Oxidative stress caused by workout is actually necessary for the benefits of that activity.
Personally I just think northern climates create a mild photophobia (happens to everyone after days of dark weather) that is much more problematic in myself due to existing sensitivities.