Well I don't think I ever had a prescription written for contact lenses, only for spectacles, but was given the CL prescription verbally by the optician.

Still, rfriel could presumably order different colours of the same lens with the one prescription if desired.

Because soft lenses are so tolerant of fit, I would have thought most people would have been OK with the same prescription for different makes of contact lens, but then maybe it's like buying shoes and the manufacturer just seems to pick a size at random and stick it on the shoe regardless

knotlob