Is amaurosis fugax like an actual curtain descending? a gray block covered half my one eye out of nowhere, no descending just came and left, 45 seconds. ophthalmologist saw nothing wrong. other ideas?

It can be.: Amaurosis fugax is simply transient monocular vision loss (only ~20% have the 'curtain' experience). Although your ophthalmological exam was normal you should definitely see your physician as there are many causes of trasient loss of vision, many of which the ophthalmological exam will not reveal.

Second opinion: It sounds ominous- you need a photo imaging of your retina and also a carotid artery ultrasound- since it was so short, may not be dangerous; hoever, get checked NOW

Stroke precursor: Amaurosis fugax is usually a precursor to a stroke/CVA or heart attack. It may indicate a narrowing of the carotid artery in the neck. This is an embolic event so may resolve without any further symptoms. I would seek further evaluation by your PCP ASAP, or ED if symptoms recur.