Originally Posted by
rbaker
Back in the day, it was a common practice. Finished stock SV lenses (AO Tillyer and B&L Orthogon) came in 0.12 increments and we all stocked laps in 0.12 increments. I can't address the efficacy of refracting to this tolerance but I do think that some refractionists thought it so, for whatever reason (ego). With the advent of the plastic ophthalmic lens we saw the elimination of these lenses primarily due to manufacturing concerns. Their elimination cut in half the number of molds and laps a manufacturer had to carry. An additional factor was the difficulty of producing polymer lenses to these exacting tolerances.
In todays marketplace it really doesn't matter. It is questionable if anyone is going to refract to this degree of supposed accuracy and it is highly improbable if one could economically fabricate lenses to this tolerance and how could the poor dispenser insure that the lenses met these exacting tolerances.
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