wearing contacts for quite a while (years and years and years) can reshape your cornea.
this happened to me for a bit, until i couldn’t wear contacts anymore. my 'script underwent quite a change. i haven’t worn contacts for about 5 years now and my eyes are nearly back to pre-contact times.
I would take that as a plausible explanation, but I haven’t worn contacts on a regular basis for several years now. One day, after years of daily wear, my eyes suddenly shifted so that I couldn’t wear them at all. Now, a few years later, I can wear them again, but can only tolerate them for 6 to 8 hours at a time. I guess I just have strange eyes!
It’s not just vision that’s the issue, it’s the complete eye health picture.
While taking my kids to get their eyes checked last year, I decided I’d get my eyes checked too. As it turns out, my vision was fine, but my intraocular pressures were quite high due to some anatomical quirk. I had no idea anything was going on and never would have known until my eyes were well and truly screwed.
Two opthamologists and two laser iridotomies later, all I can say is thank G-d for primary care!
Bah.
Profit on eyeglasses themselves is not that high. While it is true that a lens blank can cost as low as $1.00 USD you have to realize that the price only gets that low when the place buying the lenses orders in large quantities. Also, having that lens blank doesn’t get you your Rx in them either. The lenses then need to be blocked, surfaced, coated, edged, aligned, and then fit into your frame. There are several different machines that do these processes, which are expensive in themselves. Materials like blocking pads and such that are not reusable. Expensive coating liquid. (An 8oz bottle of UV coat costs several hundred dollars) . You have to pay the lab techs, the optican that helps you choose and fit your glasses, the store itself, yadda yadda yadda… I work for a large chain and even though our profit margin is higher than most doctors offices because of our volume we make a much lower percentage on each pair then other consumer goods.
Now, factor in lab errors, wacky customers that suddenly decide that the frame they chose looks horrible on them now, remakes on other doctors Rx’s… well… the profit drops even more.
But couldn’t much of the exam be automated? Especially the “Is A or B better?” part?
Is there going to be a button for “well, I am not really sure, I think the one we tried just before these two might be better, can I try that again?” And another one for “Hmmm, it seems the green is sharper than the red”?
I always feel like I’m failing that test. 
Maybe “A, B, or other” and then a list of choices for “other?” Would this not work?
I suppose part of it could. I doubt there would be anything stopping them manufacturing a robot that switches lenses back and forth in the phoropter based on a patients answers. However, someone above mentioned a different machine that was used to give them an Rx. That machine was an automated refraction system. It is kind of like the autorefractor used in the first part of the exam. The autorefractor usually gives the doctor a starting point to the exam. However, the system gives the doctor a whole prescription. These systems haven’t taken off because of their lack of flexibility. With a machine there is only yes, or no. There is no “maybe”. A machine isn’t going to be able to look at the patients current Rx and see that they have been wearing an Rx that is too strong for years, and therefore might not be happy with the full reduction in Rx that there eyes call for. That is where the doctors experience comes in. These full service machines never really took off for just that reason. They are not able to give an Rx that the patient is happy with in the widest variety of cases. If the patient isn’t happy with the Rx, that leads to remakes on the glasses, remakes on the glasses lead to the loss of profit from the eyecare business. Couple that with the expense of maintaining such a system, and the system not able to read all Rxs accurately. (Like when the patient has chewed up their cornea with poor contact lens hygiene) It is a cheaper, safer, and more accurate exam with a real live human running the show.
Is the automated refraction system the way small children and the mentally disabled are able to get proper corrective lenses. I’ve often wondered about that. There wouldn’t be much in the way of “come-backs” because those patients are the least likely to complain.
I’m beginning to see where human judgment comes into it, but not in what I quoted above. A well-programmed machine would have “maybes” and would presumably have access to medical records.
I sure hope it doesn’t. Due to the way my eyelids, the old applanation tonometry needs to be used on me to test for glaucoma, not the modern air-puff tonometry. I don’t know about you, but a machine with a tool that could blind me doesn’t seem comforting.
For now it is cheaper and better to have a human being do it. It is an art.
I suppose you could also have a computerized doctor which would ask you questions and give you a diagnosis or ask you to take some tests and the results would automatically be entered. For now it seems live human doctors do the job better. Maybe the day will come when we will not need them.
Why even have a A or B. Why not just a continuous in/out focus that you could dial in yourself ?
We talked about that further up the thread. Oddly, patients turn out to suck at deciding on when they can see properly.
Don’t they use some sort of autorefractor to guide the laser in laser eye surgery?