providing your prescription is ok, do you feel pressured into changing them every year or 18 months ? I can remember my first ever pair lasting me for years, and my last pair were certainly 4 yrs old at least.
MAS, I am an optometrist and I find that some of the newer, more oxygen-permeable lenses, scratch more easily than the older brands. Could this be why? If the lenses appear to be in good condition, I don't pressurise someone into getting new ones. Mind you. RGP wearers are few and far between these days!
I have worn RGPs since I was 15, and am currently with boots, for £12 a month I get a new pair each year and as many eye tests/after care as I can fit into a year. The optician generally says something like keep your old ones for spare though so prescription can't be changing that much, and they can't be in too bad shape
I find a lot of patients, particularly women, lose tolerance to their RGPs. They go from being able to wear them all day without a hitch to constantly being aware of the things. People with low-to-medium astigmatism can use monthly disposables, there is still very little choice for people with high astigmatism, it's still a compromise between comfort and vision, unfortunately.