My eye doctor is unable to tell me why I see what looks like a
black screen over my right eye in a semi-darkened room upon awakening after sleeping on my left side for about 30 minutes. This effect clears up after 5 minutes or so. This never happens if I sleep for several hours. I have had : MRI, Carotid ultrasound, full field vision test, blood work, etc. All tests negative. No cataracts, no glaucoma, no retinal detachments, no macular degeneration, no migraines or any other symptoms.