With mild forms of macular degeneration there may be a blurring of the central vision. YUP dead stuff floating on top of your eyeball but if it is in the same spot all the time then:
If permanent - - happened to me - I kept cleaning my glasses over and over again - it was my eye. I have a big blind spot that don't work but my mind 'makes up for it' - notice it reading but not far away. did an eye exam with a picture - doc said that I must've slept with my arm over my eyes - which I used to do alllllllll the time. Well the blood vessels in your eyes are the tiniest. I killed off my own eyeball blood vessels by sleeping with arm on the eye.
I killed off a few cones to myself. Nothing you can do except quit sleeping with arm covering eyes.