The cosmetic contact lenses are available in a limited range of prescriptions.
There is a study being done on the number of infections caused by improper use and storage of cosmetic lenses, whether in prescription powers or plano.
Plano, by the way, is the optician’s geek-speak for zero-power lenses. The Semi-Insignifigant Other and I had our own optical store for a while (boom goes the economy, boom goes our store), and I worked with him at the place he had worked before…so, although I have never WORN them (contacts are of the Devil, and putting pieces of plastic in your eyes just means that you are OBVIOUSLY a demon, and consort with the Devil on a regular basis, thankyou VERYverymuch…actually, I can’t stand to have anything touch my eyes, which is tough, since I have glaucoma)anyway, I have never worn them, but they do not impede vision when properly aligned, and BARELY impede it if out of alignment, IF they are either the US made ones or custom made in the US ones. (Custom cosmetic contacts run from $500 to $7,000 PER LENS, so unless you’re wealthy, don’t ask.)
Your basic, mass market contact that looks like a whited out eyeball or has an eightball or the cateyes or whatever does not impede sight, and if there is a small ‘blank’ area, the brain fills it in.
Anything more than a -6.00, though, and you’re SOL. And us farsighted folk are as well. (They may have changed the parameters in the past few years, but not by much.)
They leave a ‘hole’ for the iris in the lenscolor. They’re STILL a medical device, and are still, by federal law, a prescription item.
And having seen the problems caused by people wearing the non-approved contacts from Mexico and Brazil, I would caution buyers to look for a brand name and buy from a doctor or ABO certified optician, NOT a flea market or beauty supply. Permanent blue blotches on the cornea are hard to live with.