I've sight fasted during my pre-Thanksgiving Water fast. I did it hours at a time, because I had no one to take my pups out to the bathroom.
For the sight fast, I used my scarf as a blindfold. During my breaks from sight fasting, my eyes were very sensitive to light. I would have my laptop on the lowest bright setting, and my eyes would still hurt from the light. My eyes also teared up a whole lot especially when first waking up in the morning. The tearing up was similar to when I had a corneal abrasion but much worse.
Eventually, I started getting eye aches along with headaches which could also have been because of the water fast. The only thing is I never experienced aches after day 2 of a water fast. The aches was much worse on Day 5.
So I decided to terminate the sight fast for now. I'll experiment with it later by itself in order to rule out any other culprits which could have caused the aches and tearing up of my eyes.