As I get older, I get prebyopia. I have reduced “accomadation”. I am long-sighted. I can’t focus on near objects.
There are three possible solutions:
I could get glasses that make near objects appear farther away, so that I can focus on them.
I could get glasses that make objects larger, so that I don’t need to focus on them.
I could get glasses that do both: adjust the apparent distance (incidentally making stuff smaller), and correct the size (magnifying).
For those not following: glasses that adjust the ANGLE of light rays, and/or glasses that adjust the POSITION of light rays.
If I walk into the chemist / supermarket / department store and get some “reading glasses”, what are they selling?
I don’t think that’s how simple lenses work (at least, they sort of always do both).
If you are long sighted, the lenses in your eye are not strong enough to focus an image of near objects in the short distance between the lens and the retina - the lens fails to resolve these images and the focal point falls at some distance behind the retina.
Supplementing your eye’s lenses with glasses containing a convex lens will correct for this problem and allow the image of near objects to be successfully focused on your retina.
If you were to put on the opposite prescription (a concave lens), it would just make the problem worse - it would counteract what ability your eyes have to focus and throw the focal point further behind the retina - objects would not especially look ‘further away’, but they would be harder to focus.
Fyi it’s “presbyopia” and “accommodation”. Note that presbyopia and long-sightedness are not quite the same thing, although both are corrected by convex lenses. Long sight and short sight are incorrect “midpoint” lens power, usually present from birth. Presbyopia is a loss of the ability of the eye to change focal length, usually developing in middle age.
There is no fundamental difference between the positive diopter lenses used to correct long sight or presbyopia and the lenses used in magnifying glasses - both are convex lenses. When placed far from the eye and near the object, convex lenses magnify. When place far from the object and near the eye, they help the eye to focus without any apparent change in the size of the object.
This is demonstrated quite clearly in people who are extremely long-sighted and wear corrective glasses: with powerful positive diopter lenses, they see a normal-sized world in focus; but when we look at them, we see their eyes magnified.
I’ve been incredibly short-sighted since I was a child.
Therefore my glasses do the opposite of yours. I suppose they are still called ‘reading glasses’.
I’ve been using opticians all my life and recommend you do the same.
Why trust your sight to a supermarket?
I suspect they would not be called reading glasses. If you are short-sighted (nearsighted) why do you need reading glasses? Many people with nearsightedness must *remove *their glasses to read.
For presbyopia, off-the-shelf reading glasses are good for most people. They are not as good if your eyes need different diopters (I think this is unusual for presbyopia) or if you have significant astigmatism.
Also, an optician is a technician who fits glasses. Do you mean optometrist?
Last year, I went to the eye Dr. and He told me I really did not need glasses except to read. He made me a fancy pair of reading glasses. He told me the ones off the shelf were fine, but these would be like HD.
They sucked, they made everything blurry. The cheap ones at Wal-Mart worked.
Sure I could have taken them back, but then that is a whole other exam to see where he was wrong and then waiting to have them redone, I did not have the time.
In the case of presbyopia, it would be more accurate to say that the muscles that control your eyes are no longer strong enough to bend the lens into the correct shape. This is not typically due to weakening muscles, but rather to stiffening of the lens with age.
I used to wear bifocals to correct my sight for driving and for reading. Then I developed cataracts and had the lenses replaced with ones that are correct for middle and long distance. This means that I still need about 1.5 magnification for reading.
I buy reading glasses from Hong Kong at about £3.50 (£4.65) a pair, post free. They have a hard life - in and out of my shirt pocket - and usually last me about a year.
Maybe you got the wrong lenses somehow ??? Mixed up with someone else ?
Maybe you got multifocal and you have to learn to adjust your head angle …basically read through the lower part ??
A topic left out so far … A lot of people have astigmatism… This might be what confused the OP… the prescription lenses may correct for astigmatism, which is measured as a change in strength on two axis 90 degrees… how much different in power, and what angle that is at…
You say he made them. The eye doctor shouldn’t be making you anything. Assuming you’re in the U.S. he (or she) is supposed to just give you a prescription that you get filled by the qualified optician of your choice. That’s federal law, they aren’t even supposed to wait for you to ask for it, although it doesn’t get enforced unless the patient files a complaint with the FTC.
Eye doctors are not, nor should they be expected to be, trained in opticianry. No more than a medical doctor would be expected to also be a pharmacist. It’s OK for an eye doctor to have opticians on staff, but they can’t require you to use them.
Unfortunately, only a handful of states have licensing for opticians, so it’s hard for a consumer to know if the “opticians” on staff are really opticians. When I was in the field, our standard advice was make sure they are ABO (American Board of Opticianry) certified. If not, go somewhere else to get your eyeglasses.
As I get older, I can’t see what I’m typing.