Came outside for a smoke facing west on a clear sunny day with a few clouds at 11:27 am on 10/16/17. we have a lot of air traffic in the tampa bay area. i noticed a dark rectangular object at 33 degrees to the nw over a mile away. i thought it was a bird gliding at first. dark with no reflection from sun. sun was still in the east and object was west so it should have been bright if it were a plane. we are subject to military aircraft such as black hawk helo’s. object appeared a thin rectangular object and moved south in front of clouds for several seconds. in less than a mile and aprox. 100 mph it just vanished. no cloud cover when this happened. i tracked it’s known path for a while to see if it would reemerge. it did not. then i noticed my eyes were full of spots every time i blinked. similar to a photo flash but in a 20 x 20 grid of dots. this is not unusual looking up in the sky in florida but not when looking away from the sun and not in a grid pattern. not sure what i saw due to it’s distance. i know i was fully awake and conscious and saw this event clearly. the object would have been over the gulf of mexico at least a mile out.