RGP Lenses and occasionally PMMA lenses will develop a layer of deposits, that with time will build up a even with a concientious patient useing the best of care and cleaning. Usually this can be seen with either a little magnifcation or staining of a lens viewed dry. In some cases they deposits seem to be uniform and transpearent and are only evident when you see layers being removed by polishing. I suspect this is why some practioners (along with a desire to kick sales along) feel that HGP's loose permeability. The cure: cleaning and polishing the lens, yes you can charge for this and it's all profit without a wholesale bill. The patient's will love you.

But the fine line is: Don't polish lenses that do not need it. Every polishing slightly (sometimes more than) distorts the lens no matter how expertly done. You will abberate the lens slowly or rapidly, so the less unnecessiary polishing, the better.

Chip.