I never even thought of looking in other countries before reading this thread either.
Any retailer on the web will need a confirmation from a doc or optometrist before filling.
The US seems to be the only country which treats basic optometry like some kind of rocket science. Where did you guys get that idea that prescription should match so very precisely? Unless you have some rare condition +/- 0.25 dioptre doesn't make much difference. Glasses/contacts are the simplest optical instruments, not a Hubble telescope. Why do you need a specially trained person to dispense a box of contact lenses? If I want a 6-set of monthly -1.25 lenses -- just fucking sell them to me. What the hell do you need to verify with a doctor? I'm not buying a controlled substance or anything. Why did you guys make this transaction more complex than buying a roll of toilet paper? US seems to be the only developed country where I would have a hard time getting a trivial (but necessary) medical thing. Land of the free, my ass.
Also, what's the deal with vision insurance? What are you insuring against? Sudden nearsightedness? I would guess that 99% of VSP members already have a trivially managed chronic condition. And once you get a laser correction there is no point in staying in VSP anymore. So VSP is not really an insurance, but rather some kind of medical union. In theory it should help patients by increasing their collective bargaining power. In practice they seem to be doing the opposite.
A lot of it stems from the fact that different brands and types of contact lenses - even ones with the same name - vary widely in terms of material, oxygen content/permeability, and actual physical dimensions of the lens (the two variables are called the "base curve" and "diameter"). The diopter is just one axis out of 5 or 6.
A given lens in one patient will not always be comfortable or even stay adhered to another one's eyeball. This is why doctors do "fittings" where a trial version is placed and observed for a few minutes or a few days to look for side effects. Lenses actually need to move when you blink, the doctor looks for that as well. Lenses that don't move can deprive your cornea of moisture and oxygen and scar it.
That said, once you're on a lens the matter of having it renewed is a simple function of your annual examination, which is something you should be doing when using contact lenses. If you're one of those people that make 2 week lenses last 6 months at a time and sleep in them, or you are buying them in gas stations, you're risking a lot. I sleep better knowing mine are FDA regulated and recalled if problems or contamination occurs.
I'm not a ophthalmologist, but I've been wearing contacts for nearly 30 years and I respect the process. I'd rather wear 1-days for the rest of my life than undergo LASIK.
> buying them in gas stations, you're risking a lot.
How? That vending machine sells exactly the same Acuvue lenses that you can buy in US.
The real racket is with the manufacturers who segment the market with different wear regimes. Nobody can come up with an explanation of what differentiates weekly, biweekly, and monthly lenses (daily's do eliminate some unnecessary processing steps). The members of the optik guild will be aghast if one dares to violate the approved regime and wear a lens longer than the box dictates, despite being made of the exact same polymer as a longer duration equivalent.
> Where did you guys get that idea that prescription should match so very precisely?
It's often much less about the prescription than the characteristics of the material used for the contact lenses and the measurements of your eye. The base curve and diameter portions of the prescription are used to capture this.
> Why do you need a specially trained person to dispense a box of contact lenses?
There are two reasons. With the wrong set of contact lenses (e.g. off-prescription color contact lenses that people wear on Halloween), you can significantly harm your eyes due to low oxygen permeability in the lenses, lack of fit, etc. Second, the contact lens/glasses prescription renewal process forces people to get an eye checkup done, which can often allow the doctor to identify other problems (e.g. infection, cataract, etc.)
It's subjective whether or not using this as a forcing function is really the "right" thing to do, but it does prevent people from living with undiagnosed issues.
> Also, what's the deal with vision insurance?
As people get older, the likelihood of an eye issue increases dramatically. This depends on your specific policy and what it covers, but there are "insurable" (i.e. low likelihood of occurrence, very high cost) events that can occur with your eyes that your VSP policy may cover. I'm not deeply familiar with this, so I can't comment extensively on it.