reading glasses, .50 strength, how to search?
April 16, 2013 7:26 PM   Subscribe

Searching for [reading glasses .50] gets me 2.50, etc., on both Google and Amazon. has expensive ones, but I'm hoping to find good, low-strength reading glasses for the same price one would pay in a drug store. Strength .5 and/or .25. Any specific recommendations or search tips? (and what is the unit of measurement, anyway?)
posted by amtho to Shopping (8 answers total) 4 users marked this as a favorite
That was my prescription for years, and I had to get them custom made like regular glasses. I never found a pair for cheap at the drugstore, unfortunately. My eyes just got .50 worse, and it's a hell of a lot easier finding 1s, I tell ya.
posted by looli at 7:35 PM on April 16, 2013

Why not just go to a discount online glasses company and have them made? You can even choose the frame. Places like Zenni Optical and Goggles4U can get you a complete pair of prescription glasses in a basic prescription like that for $12-25, shipped. I've bought tons of glasses that way.
posted by DirtyOldTown at 7:52 PM on April 16, 2013

Best answer: It might help searching for 0.50. That got me this.
posted by supercres at 8:05 PM on April 16, 2013

Can't help you finding the glasses, but I can help you with the units. There is no unit of measurement for magnification because it is the ratio between the apparent size of an object (or its size in an image) and its true size, and thus it is a dimensionless number.
posted by Rob Rockets at 8:55 PM on April 16, 2013

The unit of measurement of lens power, including for eyeglasses, is the Dioptre, i.e. inverse metres.

Agree that the cheapest way to do this is get them made up by an online prescription glasses maker. If you shop around, choose standard frames, and/or wait for the regular sales on Lensway you may be able to get them for under $/€/£10.
posted by caek at 1:12 AM on April 17, 2013

Zenni optical makes cheap glasses, and they are better than the drugstore ones. You have to tell them your pupilary distance, and that's key to comfortable reading. I just bought a perfectly acceptable pair of glasses for under $12, shipping included.

The unit of glasses lens strength is the diopter.

Standard advice: get a checkup from an optometrist and get a prescription for the exact correction your eyes need. It will be worth it in the long run. Drugstore "cheaters" are not great for your eyes unless your eyes happen to conform to the way they are made.
posted by gjc at 3:13 AM on April 17, 2013

Response by poster: I'd heard of diopters, but is that the same unit used for cheap reading glasses? They seem to be doing an entirely different job than regular prescription glasses for driving...
posted by amtho at 5:06 AM on April 17, 2013

Best answer: One is positive, one is negative. The lens in your eye hopefully focuses right onto your retina. If it focuses a little bit in front of your retina, you need distance glasses in a negative diopter to widen out the focus a bit so it is dead on. If your eye focuses too far behind the retina, you need a positive diopter (magnifying) lens to narrow the focus a bit.

They use diopters because they add and combine linearly. If you put two +1 diopter lenses together, it ends up acting like a +2 diopter lens. If you put a +2 in front of a -1, you end up with +1. Etc.
posted by gjc at 10:39 AM on April 17, 2013

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