In a way, it makes sense about reading glasses. A theorgy: if you had a parasite infection in the head, it would cause some swelling or pressure on muscles, nerves, and causing less blood flow to the eyes. Freeing this up would cause clearer vision.
When I was younger, I had injured my neck and all the muscles went flat. I was bedridden for a short period of time. The doctor told me that I couldn't watch tv because my eye muscles would affect the neck muscles in a slower recovery. I was shown a chart of the connected muscle groups, nerves, etc. There were times that I couldn't stand not do anything and briefly watched tv. I noticed that my vision was affected and my neck muscles reacted to the eyes movement.