How to heal your Eyesight and expand your Insight by Jacob Lieberman, O. D., Ph. D.

This book explains the connection between our worldview and our vision. The eyes, like the rest of our body, have the ability to heal themselves. Wearing corrective lenses makes our eyes lazy and gradually worsens our vision even more. Awareness, meditation, and eye exercises have helped thousands of people to see better.

Wear only at the beach or on a snow mountain

Major photoreceptors are located in the retina of the eyes. As sunlight hits these receptors a signal is send to the skin to produce more melanin, a pigment that basically protects the DNA from ultraviolet rays. Sunglasses filter sunlight and hence minimize the melanin production and leave the DNA unprotected making humans (we are the only ones to wear this things) more prone to skin cancer.

http://www.uphs.upenn.edu/news/News_Releases/jun07/photoreceptor-cilia-proteins-photo.html