Opticians are going to argue about this as if their livelihoods depend on it, and in fact they just might. They’ll argue that you need to be looking through the focal center of the lens. They'll argue that eyeglasses alignment is a critical issue with vision. Let's face it, eyeglasses are not exactly a precision system.
The frames are nothing more than a chassis for a crude lens. It is crude too, it has to be by definition. If it wasn't we'd need to lock our eyes into place to see properly.
The fact of the matter is that we've all had glasses that slide down our faces, in some cases for years at a time. Is it fun? Nope. Can we still see? Indeed we can and have -- even with the $300 to $400 eyeglasses you're probably wearing now.
All you need to do is look at the walls in your local mall store to see that eyeglasses are a matter of fashion for most. If it was about the preciseness in which they fit and performed, no optician with a conscience could be in the same room with half of frames they'll gladly sell you. If it was only about utility there would be three frames (metal, brown plastic, and black plastic) in a multitude of sizes.
So, these chunks of polished plastic over your eyes are designed to be able to move on your face. Your face contorts, your hands bump the frames, your sweat and oils cause slippage… all of these things coupled with wear and tear, actually require the lack of precision.
The perfectly fitting pair of glasses is a fallacy. It's just another ploy to make you spend way too much for your specs.
- At November 15, 2006 at 3:29 AM Chef said...
I disagree - there is a perfect fit, but this is something that can often be adjusted to fit, and can be acquired with many different frames. The fit also affects how the lenses are aligned with your eyes. I can see eyeglasses being a precision system in that if they're slightly off, they can make using them hell if you have a strong prescription.
Case in point: my current pair of glasses had the right arm's springback arm snap for the second time(and I was out of warranty), so I ordered a replacement arm for it. After having the replacement arm reattached, the frame was then not adjusted for my head, and my glasses were frustrating to use as they kept falling down my nose(and not just a little) and looking through the lenses made me feel crosseyed.
Getting them adjusted gave me the "perfect fit" - they didn't fall down my face, they sat properly, vision was as it should be, no eyestrain. If I shook my head around, the glasses wouldn't move out of place. (FYI: I couldn't get them adjusted originally because I work overseas now and my brother brought them to me)
So, the moral of the story is that you need to get a frame that can be adjusted to achieve that perfect fit. There's pairs that will obviously be wrong, like frames that are too narrow for big-headed people, and it's possible to have frames too big to adjust to a good fit. So, you need to get a frame that's at least in the general area of fitting your head. But beyond that, just find someone who knows what they're doing to adjust your glasses and you can avoid problems like "dented" ears and red marks under the nose pads, both indicators that the glasses aren't balanced properly. I wish I knew this when I was in middle school, as I had to deal with these problems all the time, and they affect you every day, constantly.
Having a frame that gets bent out of shape with a touch or one that keeps slipping down to the "nutty professor" position is totally unacceptable, and there is no fallacy to the idea of the perfect fit. The trick is finding that no one pair has the perfect fit - you can make it happen with most eligible pairs.
- At December 8, 2006 at 10:16 PM Anonymous said...
Looking through the optical centers of the lenses is important, especially for high prescriptions. When the lenses are decentered vertically, this is especially bad (we cannot tolerate vertical changes as much as we can tolerate horizontal ones.) For a prescription of + or -1.00, if decentered one cm away from the optical center vertically, this could cause the person to be symptomatic (eyestrain, headaches). The higher the precription, the less distance your optical center can be decentered before having symptoms. Contrary to what you may think, glasses are a "precision system."
- At January 9, 2012 at 10:01 PM TulsaEyeGuy said...
Sometimes dredging old posts is good- For the record, I'm an ABOC optician starting on a new concept in dispensing and I'm totally with the author on all the price gouging issues of the mall and such.
However, I must beg to differ on lenses being only low tech and proper fit not being an issue. There are literally hundreds of relatively new lens designs, backed by great vision research, offering incredible improvements in sight. Aside from making ugly, annoying, best vision diminishing glasses, lousy fit and an optical center just a couple millimeters off either way in a typically moderate Rx like -2.50 -1.50 x 180 WILL create enough prism to cause neural suppression of the visual stream from one eye, within a couple weeks time. Don't screw with your vision. You're better off not wearing something that is actually causing strain or fatigue.
I'm a good case in point:
My Rx is -7.00 -.25 x120 OU; and just the act of reading, which naturally converges my eyes heavily into a base-in prism region of the lens, required I get progressives at 20 y.o. to offset the near-focus induced prism.
It's proven that people with tired eyes from poor fit/focus are less productive and suffer from more neck pains (Sheedy, 2000). There's a better solution.
The TulsaEyeGuy knows what he's talking about!