Tried and Tested: Norville Optical's Digitor DHD lens

Optician’s recent testing of DeRigo’s Lozza Sartoriale process prompted a call from Norville Optical. How could a truly bespoke spectacle offer not include the manufacture of an individualised lens, it asked.

A request for mono PDs and pupil heights followed which were duly taken using the frame in the usual wear position. The fit was verified as excellent and the measurements provided. The frame was then sent to Norville to be glazed.

When returned to us, the personalisation promised by Norville was in the form of its Digitor DHD lens. This latest generation free-form lens has a variable front surface base curve designed to provide the best optical base curve across all viewing zones. Depending on the power, each lens comes from a different section of the 'Elephant’s Trunk' curve lens' function. In lens theory the Tscherning ellipse principle states that every lens power has an ideal base curve. That base curve conforms to the curve on the elephant’s trunk.