What is your age? What medical conditions do you have?
There are 3 possibilities.
One is the retina. Even though you have had surgery in one eye and prophylactic laser in the other, the retina can still detach. Shadows coming over vision is one sign of a detachment.
Another is just floaters. The gel in the eye can break up and float around.
Finally, and the most concerning, is amaurosis. This occurs when a blood clot drifts up and temporarily occludes the artery to your eye. This is similar to a TIA. It is concerning because there could be other clots and bigger ones that can cause more serious problems (like a stroke).
I think you need to see an ophthalmologist to make sure the retinas are OK. You may also need to get a carotid ultrasound (to look for clots in the arteries in your neck) and a lipid profile (to look at the cholesterol level).
Hope this helps and thank you.