I recently prescribed a few high minus progressive lens (-6.00DS and above). When I tried to verify the add by (measuring the back surface), the reading did no show the required add.
take this Rx for example -7.50DS add +2.50.
using the lensmeter, (measure through back surface) it shows the reading power to be -5.50 meaning add is only +2.00. however when I measure the reading area through the front surface of the lens, the reading is -5.00DS.
however, when I verify plus power progressive lens, i do get the add power by measuring it the normal way, ie through the back surface of the lens.
Can someone enlighten me on this?
Thanks.
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