Life Expectancy for Eyeglasses?

Factual Questions
1

Assuming that one’s perscription stays that same that is…

I recently got a new pair of glasses and was told that the perscription didn’t change much from my old glasses (which I’ve had for 4+ years). I asked the doc if the new 'scrip was enough of a change that it warranted a new pair of glasses. Probably the wrong person to ask, but I phrased it in such a way that he’d be hard pressed to come out and say, “I haven’t met my quota yet, so yes, it will be a good idea.” And I’ll be damned, the new glasses are quite spectacular and allow me to see things at a distance with significantly more acuity than my older glasses.

One of the reaons I chose to get a new pair is becaue the frames on the old ones are beat up. I’m generally in the store about once or twice a month to fix them after they get smashed in some form or another and the two lenses got twisted such that they were not, nor apparently could ever be, on the same vertical plane again (I’ve frustrated a lot of otherwise pleasant repair techs with that request). As a result, I could clearly out of one eye at a time, depending on how I put the glasses on.

Another reason I chose the new pair was that the lenses themselves were pretty scratched. I spoke to a non-optometerist who advanced a theory that over time scratches (either visible or in-) would “cloud” up your lenses and change the perscription/definition of that pair of glasses.

My questions:

  1. Is that theory of scratches true?

  2. If the frames getting beaten up and changing the planes that the lenses reside on occurs (along with question 1, if true), what is the standard life of a pair of glasses, even if my perscription doesn’t change?

2

Definitely. Scratches add diffraction, an edge effect that works to reduce resolving power (sharpness) of a lens. The buildup of even small, shallow scratches over time will eventually work to reduce the sharpness you experience from a given set of specs significantly. Requesting the scratch-resistant coating on plastic lenses, along with proper cleaning and storage habits will greatly extend the life of your lenses.

3

I had my previous glasses for 18 years before they began to lose effectiveness, but they were also starting to wear out physically (accumulated scratches and the plastic earpieces starting to crack). They were pretty good quality from a good optician, though. My present pair were fairly cheap and from a chain, and are in in almost as bad shape physically after 4 years than the others after 18. (Also I now need bifocals :frowning: ).