What's the difference between reading glasses and ordinary eyeglasses?!
Question: You can buy reading glasses cheap, without a prescription. You only have to know a single number, such as 1.75 or 3.50, indicating how powerful the reading glasses should be, according to how bad your eyesight is.
What does an ordinary eyeglasses prescription look like? Does it have more than one such number? One for each eye, or what? Are they the same kind of numbers? What do they mean, in terms of units of measure or whatever?
Answers: You can buy reading glasses cheap, without a prescription. You only have to know a single number, such as 1.75 or 3.50, indicating how powerful the reading glasses should be, according to how bad your eyesight is.
What does an ordinary eyeglasses prescription look like? Does it have more than one such number? One for each eye, or what? Are they the same kind of numbers? What do they mean, in terms of units of measure or whatever?
First of all, over-the-counter glasses are only intended for reading/close work. So in that respect they are obviously totally different to presciption glasses that are intended for distance vision.
Prescription glasses intended for close work are usually not only better quality, but as you rightly surmise, designed for the specific needs of each eye of the wearer. They also allow for the specific distance between the pupils of the wearer, and are adjusted to fit the wearer's face.
That said, if a person has no other eye problems, over-the-counter reading glasses are an acceptable economical alternative, especially for people who lose glasses easily.
Those cheap reading glasses are just magnifying glasses. The numbers give the amount of magnification is all.
With prescription glasses There is allot more to it. Like of one eye is weaker than the other eye. Like of you are far sighted or neat sighted. Each one requires a different prescription.
And whether you need bi focals or not. i.e. you can be far sighted and require bi focal lenses for up close but at the same time require different strengths because of your eyes being different.
In short those cheap reading glasses are no substitute for prescription glasses.
Those reading glasses you see in stores are generally meant for older people who can no longer see well close up. Typically, people who had perfect vision all their lives buy them. I've heard that for those people, these glasses are the better alternative to getting prescription glasses. Not only are they a lot cheaper but just as effective.