Surely that can't be true. Can it?
There is something called amaurosis fugax, and it is a sudden blindness, that lasts for just a couple minutes, and only in one eye.
It happens when a person approaches orgasm, and the exertion causes a dam to form in the blood vessels in one eye, and the sight to go for a couple minutes.
Some happy sufferers are successfully treated with blood thinners.
(More importantly, amaurosis fugax is a also a sign of pending stroke, and should be checked out. People describe it as a shade being pulled down over the eye.)