Most patients going in for radical eye surgery hope the surgeons won't have an accident that makes their vision any worse.
Some wake up to find they can see colors far beyond the range humans are normally able to see.
There is increasing evidence that patients who have cataracts, cancer or other eye problems treated by having their corneas surgically removed and replaced with artificial alternatives, often end up able to see colors in the ultraviolet range of the spectrum – colors of light visible to night-hunting raptors, some lizards and, oddly, ants, but not to humans.
If this were a comic book or science fiction novel, this is where you'd find descriptions of strange creatures visible only in ghostly purple light, strange doors undetectable those not afflicted by aphakia, whole civilizations and a really coherent plot involving a threat to the human race that can be foiled only by humans able to see into The Purple.
Unfortunately, while the ability to see farther into the ultraviolet than other people is cool, it's not exactly a superpower. (It does do some really wacky things to the colors you're used to seeing, though.)
The colors of light classified as ultraviolet are only one step above the normal human visual range, for one thing.
Even un-aphakian humans can see some ultraviolet – which is used primarily to make raves and clubs look cool under black light (for the hipsters) or to identify bodily-fluid stains on sheets and furniture in hotel rooms (for the germophobes).
While it's possible to see black-light lightbulbs and see the darkish cast they throw on objects that don't glow ultrawhite under them, most humans can't actually see the color of ultraviolet light.
Most people are able to see wavelengths of light ranging from 380 nanometers to 750 nanometers in frequency, a range that goes from dark red on the low-energy end of the spectrum, to violet on the high end.
Our eyes are actually able to see farther into the ultraviolet, but most of those higher-energy, skin- and eye-damaging rays are filtered out by the cornea itself.
Cut off the cornea and, unless the artificial replacement is designed to filter out the UV, you get to see more colors than other people.
Bad luck if you're not a fan of purple, though.
Alek Komarnitsky, an engineer who had his corneas replaced as a treatment for cataracts, describes UV as a blue-violet glow that makes a lot of things more interesting to play with – ultraviolet flashlights, colors of clothing and personal objects and monochromators that test the specific frequency of the light range he can see (He's an engineer; that's how engineers play. Most of you would do the same thing.)
Only about 3 percent of aphakia patients get the extra UV vision, but who gets it and who doesn't has more to do with the sensitivity of their photoreceptors, not whether they're aliens like the character Kevin Spacey played in K-PAX (who believed his ability to see ultraviolet was evidence he was an alien).
Those who do have to wear "blue blocker" sunglasses that block much more ultraviolet than most shades, to protect their eyes from the same high-energy rays that cause sunburns, make colors exposed to it fade toward plain white and break down the epoxies and resins that hold together the fibers in fiberglass, carbon-fiber and other manmade materials.
It doesn't let victims see into the octarine, however, the color most clearly associated with magic according to astro-fantasist Terry Pratchett, who describes octarine as looking to those who can see it (wizards and other magic workers) as a "greenish-yellow-purple."
According to Pratchett's documentation of the civilization of Discworld there is a lot more to see in the octarine than there is in the ultraviolet, though Pratchett also said it's better not to see many of the things visible only at the magical end of the spectrum.
Humans whose vision has been extended up the energy range of the electromagnetic spectrum don't have to worry about the downside of those visions, but then they don't get to be superheroes, either