Last Wednesday when I had my eye exam, it cost a little more, (what doesn't nowadays?), but they also did something more -- they took a picture of the inside of each eye. The chart on the wall showed some large grapefruit with a yellow nipple crossed with red veins -- very pretty from an artistic standpoint.
When she finished and displayed mine, I could easily see that they matched the "normal" set. There were a few darker areas in places, which she called "freckles" and said were normal. She also said that in future exams, these would be compared to be sure they did not grow.
This all made me think of a science fiction story I'd read long ago about an alien who was living in America incognito. He had an old housekeeper who was used to his "peculiar ways" (he was famous for something, but I forget what). For some reason, he had to have an identity scan, which involved retinal prints. He tried to talk them out of it, and one examiner said, prophetically, "Nobody ever went blind from a retinal scan."
I think the alien was afraid of being found out to be an alien, but, of course, he went blind and the rest of the story was quite sad as he was totally reliant on this old woman who was not his intellectual equal at all.
I must not be an alien... I didn't go blind. :-)