The eyes isn't mystical and it fails at spectacular rates, which is why a large percentage of the population wears glasses/contacts/Lasik. Also, cataracts. Retinal detachments. Stigmatism. Floaters.

Also, why human eyes suck in general:

Humans see in only three colors. Some fish see five. (A very few women are tetrachromats; they have four types of color receptors

• Humans cannot see into the ultraviolet, like bees.

• Humans cannot see infrared, like pit vipers and some fish.

• Humans cannot easily detect the polarization of light, like ants and bees.

• Humans can see only in front of themselves. Many other animals have far greater fields of view; examples are sandpipers and dragonflies.

• Human vision is poor in the dark; the vision of owls is 50 to 100 times more sensitive in darkness. Some deep-sea shrimp can detect light hundreds of times fainter still.

• The range of distances on which one may focus is measured in diopters. A human's range is about fourteen diopters as children, dropping to about one diopter in old age. Some diving birds have a fifty-diopter range.

• The resolution of human vision is not as good as that of hawks. A hawk's vision is about 20/5; they can see an object from about four times the distance of a human with 20/20 vision.

• Humans have a blind spot caused by the wiring of their retinas; octopuses do not.

• The Four-eyed Fish (Anableps microlepis) has eyes divided in half horizontally, each eye with two separate optical systems for seeing in and out of the water simultaneously. Whirligig beetles (family Gyrinidae) also have divided compound eyes, so one pair of eyes sees underwater and a separate pair sees above. '

• The vision of most humans is poor underwater. The penguin has a flat cornea, allowing it to see clearly underwater. Interestingly, the Moken (sea gypsies) from Southeast Asia have better underwater vision than other people.

• Humans close their eyes to blink, unlike some snakes.

• Chameleons and seahorses can move each eye independent of the other.