That’s great for farsighted people, but I’m nearsighted.
Instead of $10 a pair I have to get a prescription and $100 “custom” glasses.
One of those 20-20 shows proved the “custom” glasses were of the same quality as the pharmacy ones.
Liability. You aren’t likely to get sued over an accident causing loss of like blamed on the wrong persciption reading glasses.
Haj
If you’re nearsighted the reason should be obvious to you. At all veiwing distances your eyes are out of focus, even close up, however, the effects are much less noticeable at close distances (the reasons for this are somewhat complex, optically, but you can easily oberve this for youself). So, it’s much easier to make a few strengths of “reading glasses” so that the correction is close enough for most farsighted people to be able to read comfortably. But correcting nearsightedness for far distances requires much more precise control over the lens curvatures, so a small range of strengths is completely unsuitable for most people. When you throw in correction for astigmatism, it becomes even more complex a problem.
Well, and besides, reading glasses go to about +2.75 max. My contacts are -4.5. I have a feeling that anyone so far-sighted they need +4.5 would be better off going to the optometrist, too.
Oh, another thing I just thought of - reading glasses are not actually designed or inteded to be used by “farsighted” (hyperopic) folks - they are intended to be used by folks with presbyopia (the so-called old-age farsightedness). I, in fact, have myopia (nearsightedness) AND presbyopia, like alot of middle-aged and older folks. We are alot the ones wearing the bifocals. Or, like me, wearing contacts all day but reading glasses when we need to see close up.