As has been mentioned, there are some ancient lenses, and some have even been found in places where fine work was done. The problem is that you need a suitably clear material to make this out of – ancirent lenses were generally made of very clear rock crystal.
You’d think that glass would be the obvious material to make lenses out of, but making clear, clea, bubble- and striation-free glass isn’t trivial. A lot of ancient glass was simply unusable for making lenses out of.
One suggestion is that a lot of the round containers we’ve found from ancient Rome were actually used as maginifiers – a relatively thin0walled glass vessel would be error-free enough to not cause problems. If you then filled it with clear, clean water you’d have a magnifier much more transparent than one made of glass alone. and, as the quote Exapno gives shows, the use of water-filled glas vessels as magnifiers certainly was practiced in Rome.
One problem is that clear water often doesn’t stay clear. Things grow in it. So every now and then you have to wash them out.
As for correcting eyesight, I have made the suggestion in an optics journa;l that ancient people might simply have used pinhole glasses. Or, more likely, pinhole lorgnettes or monocles.
It doesn’t require very clear glass or rare clear rock crystal. It doesn’t require the grades of polishing grit of different size and the skill needed to perform optical grinding and polishing. All you need is a suitable hard material and an awl or drill (which the definitely had back then. People have been drilling holes in beads since before history). Drill a hole in a piece of leather, wood, bark, seashell, horn, or other suitable material and hold it in front of your eye. You’re restricted the rays that cause the blur. You’ve cut down on the amount of light, but you’re traded it for a clear image of a distant object (for a myope). I diwscovered this principle as a kid – I have to believe plenty of others have.
The device probably wouldn’t take the form of a pair of eyeglasses. I suspect it’d be in the form of “monocle” that could be held in place between the cheekbone and brow ridge, or as a “lorgnette”, with the pinhole in a holder on a stick that you could hold in front of one eye (the adbvantage of the “monocle” was that it kept your hands free).
Why haven’t these been discovered? They probably have – but how many people would associate a piece of wood/bone/shell/whatever with an eyeglass substitute? To most people – including archaeologists, it’s just a piece of stuff with a hole in it. I’ve pointed out several circula devices with central holes of the right size in museum collections that would serve the purpose.
The same idea is behind the Pinhole Glasses they sell on late night TV, or in the backs of magazines. They do work, but at the cost of illumination, and with some difficulty.
A Contributor to a backpacking magazine suggested using this idea if you’re a nearsighted outdoorsman (woman) who lost their glasses. Burgess Meredith could have read from his post-apocalyptic library if he thought of this!
The earliest example of pinhole “glasses” that look like glasses were reported from India, but I traced these back to central Asia, perhaps a thousand years ago.
An added advantage of using a pinhole “monocle”, by the way, is that it lets you hold so,mething much closer to the eye that you can normally focus. It thus effectively acts as a magnifier, letting you see finer detail than yo could see without it – and, again, you could get such a magnifier without having access to error-free glass, crystal, or polishing technology.