# eyeglasses: why prescription? **URL:** \ **Category:** Factual Questions\ **Created:** [October 18, 2016, 5:08pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955 "2016-10-18T17:08:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [October 18, 2016, 5:08pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/1 "2016-10-18T17:08:38Z")
I just picked up a pair of reading glasses; this marks the first time in many years that I’ve been able to clearly identify pixels on the screen. 🙂 It was pretty easy to get these: I just walked into a drug store, tried on various pairs to see what worked best, paid $10 and walked out. So what do prescription eyeglasses do that this method of eyewear selection won’t? ---
**Author:** ![DinoR](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dinor/32/2821_2.png) [@DinoR](https://boards.straightdope.com/u/DinoR)\ **Post date:** [October 18, 2016, 5:16pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/2 "2016-10-18T17:16:36Z")
> [@Machine\_Elf](#): > > So what do prescription eyeglasses do that this method of eyewear selection won’t? Correct for my astigmatism; IIRC the majority of those wearing glasses have some astigmatism. Correct distance vision. Provide a more accurate level of correction for reading than simply picking the off the rack reading glasses that are closest. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [October 18, 2016, 5:25pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/3 "2016-10-18T17:25:35Z")
> [@Machine\_Elf](#): > > So what do prescription eyeglasses do that this method of eyewear selection won’t? You bought two unregulated magnifying lenses attached to a frame. They do not replace a pair of prescription glasses where each lens is tailored to specific issues of each eye, nor the physical distance of the center of each eye within the frame. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [October 18, 2016, 5:26pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/4 "2016-10-18T17:26:19Z")
Bifocals and trifocals. You can go to the drug store and get OTC medications for a myriad of problems. But sensible people still use prescriptions for ailments that aren’t level one minimal problems. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [October 18, 2016, 5:39pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/5 "2016-10-18T17:39:50Z")
I remember a charity about ten years ago that sent people’s old glasses to needy folks in the third world. The idea was that glasses picked out of a bag that were close to your prescription were better than no glasses at all. I haven’t heard about it since. I assume that’s because “close enough” just doesn’t cut it for glasses beyond basic Walgreen’s readers. ---
**Author:** ![iceiso](https://avatars.discourse-cdn.com/v4/letter/i/3be4f8/32.png) [@iceiso](https://boards.straightdope.com/u/iceiso)\ **Post date:** [October 18, 2016, 5:52pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/6 "2016-10-18T17:52:06Z")
Drug store glasses also won’t have options like scratch/glare/smudge-resistant coatings, or high index lenses. These things are incredibly helpful for those who have high prescriptions and/or wear their glasses nearly every waking moment. ---
**Author:** ![cher3](https://avatars.discourse-cdn.com/v4/letter/c/da6949/32.png) [@cher3](https://boards.straightdope.com/u/cher3)\ **Post date:** [October 18, 2016, 6:37pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/7 "2016-10-18T18:37:20Z")
In addition to the things already mentioned, some of us have very different requirements in each eye. One of my eyes requires far more correction for distance than the other. I also have astigmatism. In contrast, I actually tend to take my glasses off for extended periods of reading, other than on a computer screen. ---
**Author:** ![Iggy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/iggy/32/3364_2.png) [@Iggy](https://boards.straightdope.com/u/Iggy)\ **Post date:** [October 18, 2016, 6:50pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/8 "2016-10-18T18:50:59Z")
> [@DrCube](#): > > I remember a charity about ten years ago that sent people’s old glasses to needy folks in the third world. The idea was that glasses picked out of a bag that were close to your prescription were better than no glasses at all. > > I haven’t heard about it since. I assume that’s because “close enough” just doesn’t cut it for glasses beyond basic Walgreen’s readers. Lions Club has an [eyeglasses recycling](http://www.lionsclubs.org/EN/how-we-serve/health/sight/eyeglass-recycling.php) program. Still going strong. Close enough is of great benefit to those who have not been able to see clearly years for lack of an eye exam and glasses. **Mrs. Iggy’s** family falls in this category. Her aunt got her first pair of glasses when she was over 50 years old. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [October 18, 2016, 6:59pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/9 "2016-10-18T18:59:28Z")
> [@cher3](#): > > In addition to the things already mentioned, some of us have very different requirements in each eye. One of my eyes requires far more correction for distance than the other. I also have astigmatism. > > In contrast, I actually tend to take my glasses off for extended periods of reading, other than on a computer screen. Heh. I’m blind in one eye. The optometrists call it a balance lens, and I really don’t know how much of a price break I get. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [October 18, 2016, 7:10pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/10 "2016-10-18T19:10:34Z")
I used to think eyeglass donation was a good idea, until I read [this essay](https://www.bloomberg.com/view/articles/2012-05-03/recycling-eyeglasses-is-a-feel-good-waste-of-money), which argues that examining, sorting, testing and transporting donated glasses, of which only 7% are typically usable, costs charities more than making new ones. –Mark ---
**Author:** ![Balthisar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/balthisar/32/2825_2.png) [@Balthisar](https://boards.straightdope.com/u/Balthisar)\ **Post date:** [October 18, 2016, 7:53pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/11 "2016-10-18T19:53:16Z")
> [@Machine\_Elf](#): > > So what do prescription eyeglasses do that this method of eyewear selection won’t? Rent seeking. Same reason you need to a licensed decorator in Florida, for example. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [October 18, 2016, 8:40pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/12 "2016-10-18T20:40:22Z")
You **do not** need a doctor’s prescription to buy eyeglasses in the USA. Individual vendors may opt to require it of course, but you can input any numbers and buy online. Contact lenses are regulated medical devices and you **do** need a optometrist’s prescription. The glasses you buy in the drugstore are all meant to correct farsightness or presbyopia. But most young people who wear glasses need them for nearsightness. Aside from the relevant points made above, you might argue that wearing the wrong prescription while reading is a smaller concern than driving with the wrong prescription! ---
**Author:** ![gkster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gkster/32/14107_2.png) [@gkster](https://boards.straightdope.com/u/gkster)\ **Post date:** [October 18, 2016, 9:55pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/13 "2016-10-18T21:55:37Z")
My prescription glasses are complicated: they give me correction for myopia (near-sightedness) and astigmatism. Each eye has a different degree of correction. I’ve been wearing glasses since I was 7 and I’m so near-sighted that I can barely function without them. Every time I go to the optician it takes at least 15 minutes of testing different combinations of lenses to find the prescription that enables me to see without distortions and blurrings at the edges of objects. So there’s no way I would be able to go to a drugstore rack and find glasses that would give me the correction that would enable me to function, catch a train, drive–well, maybe if there were a drugstore rack with 8000 combinations? And I ordered a spare pair of glasses from a mail-order company; the quality was fairly good, but compared to the glasses from my optician the prescription was a little off. If the correction provided by my contact lenses is a 10 and the correction from my good glasses is a 9.5, the mail order glasses are an 8: good enough for spares that cost just $15, but if I had gotten them from my optician I would have asked for them to be re-done. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [October 18, 2016, 10:36pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/14 "2016-10-18T22:36:27Z")
If you have a specific problem or want bi/trifocals then you need a prescription. If you are like millions of men, becoming short sighted with age and need some magnification, then ÂŁ10 from a store are fine. I had cataract surgery on both eyes, which means that my distance vision is fine, but I need glasses to read or use the computer. I buy mine at ÂŁ3.00 a pair from a supplier in Hong Kong. At that price they are disposable, and as I keep them in a pocket to use when I need to read anything, they last less than a year on average. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [October 18, 2016, 10:42pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/15 "2016-10-18T22:42:29Z")
I have bifocals, so drug stores wouldn’t cut it. But I suspect a good reason is that this encourage people to get eye exams to catch problems before they got too bad. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [October 18, 2016, 11:06pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/16 "2016-10-18T23:06:01Z")
I have progressives, which you cannot get in a drugstore. I also have about 3 degrees of cross-eyes, which can be corrected although owing to another serious problem isn’t. I probably have some astigmatism. That said, if all you need are reading glasses, the $10 glasses you get in the drugstore are fine. I used to use them until I developed other problems. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [October 18, 2016, 11:59pm UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/17 "2016-10-18T23:59:14Z")
> [@Balthisar](#): > > Rent seeking. Same reason you need to a licensed decorator in Florida, for example. Don’t be silly; people have already posted plenty of reasons why prescriptions are needed. The magnifiers are fine if you’re a little nearsighted. If you’re farsighted, or have astigmatism, or have different vision in each eye, the drug store glasses are useless. They also can keep you from getting a full eye exam. You don’t know if you have macular degeneration or glaucoma or cataracts or other eye problems unless you see a doctor for them. Even if you use reading glasses, you should have your eyes checked for anything like that. Or just go blind. It’s your choice. ---
**Author:** ![JWT\_Kottekoe](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@JWT\_Kottekoe](https://boards.straightdope.com/u/JWT_Kottekoe)\ **Post date:** [October 19, 2016, 2:51am UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/18 "2016-10-19T02:51:20Z")
One point that has not yet been made is that, for reading vision, you can correct for an out of focus image by moving your head closer or further away. Your eye can also accommodate by adjusting the lens, but the ability to move your head allows you to get by with a less precise lens in your glasses. The same does not apply to distance vision. If you are looking at a mountain, you can’t bring it into focus by moving your head closer or further. ---
**Author:** ![Son\_of\_a\_Rich](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/son_of_a_rich/32/5439_2.png) [@Son\_of\_a\_Rich](https://boards.straightdope.com/u/Son_of_a_Rich)\ **Post date:** [October 19, 2016, 6:18am UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/19 "2016-10-19T06:18:08Z")
OT, but whatever happened to those goofy looking round adjustable glasses being sold on tv not long ago? ISTR Penn Jillette being one of the hawkers. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [October 19, 2016, 8:31am UTC](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955/20 "2016-10-19T08:31:24Z")
> [@markn\_1](#): > > I used to think eyeglass donation was a good idea, until I read [this essay](https://www.bloomberg.com/view/articles/2012-05-03/recycling-eyeglasses-is-a-feel-good-waste-of-money), which argues that examining, sorting, testing and transporting donated glasses, of which only 7% are typically usable, costs charities more than making new ones. > > –Mark My local “recycle your glasses” charity works through glasses stores with in-house optometrists; a lot of that work is donated by the stores. [Next page](https://boards.straightdope.com/t/eyeglasses-why-prescription/768955.md?page=2)