We all like brand new charts for our clinics and trials etc. but I have a number of old charts - either yellowed plastics or grubby looking Pelli Robson's etc. I'm struggling to find anything on the published shelf-life of these products. Can anyone assist?
A good idea is to measure the contrast of the test with a light meter.
Jane, contrast is a critical measurement and although these charts are rather costly I would advise to discard them because of the yellowish plastic background. This is probably afffecting the overal quality of the performed test ,
Thank you - I agree, but can I find any recommendation from the manufacturers on shelf life? None at all. I have it in my head that the photographic paper of the Pelli Robson has a shelf life of 2 years but I can't find reference to it anywhere. In the meantime at the hospital we still have the oldest, based and yellowed charts imaginable. Tsk tsk.. For research purposes we now have a rather expensive looking photometer.
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