A Stone of Our Own
Two-hundred-and-seven years ago, French soldiers in
Napoleon Bonaparte’s Egyptian expeditionary force
were digging the foundation for a fort near the town
of el-Rashid (Rosetta) when they uncovered an
ancient, 1.5-meter-high slab of dark stone. The Rosetta
Stone, as it came to be known, immediately became an
object of immense interest among Egyptology scholars. They were
intrigued by the three sets of inscriptions on the stone. Two were written
in hieroglyphics, which at the time were indecipherable; the third was
written in a known language, ancient Greek.
Rubbings were taken of the inscriptions and sent back to France for
study. A scholar, Jean Champollion, translated the hieroglyphics, thus
decoding the mystery of the ancient language. It took him 20 years.
Fortunately, you won’t have to wait that long to figure out the meaning
of our Rosetta Stone. Dr. Palmer R. Cook, L&T’s optics and dispensing
expert and director of professional education for Diversified
Ophthalmics, has done the digging for you. In our blockbuster cover
story, “Decoding the Issues of Index, A Rosetta Stone for Eyecare,” he
offers eyecare practitioners a practical tool to help them select the
most appropriate material for a patient’s lenses. By following Dr. Cook’s
straightforward method, ECPs can use a number known as the curve
variation factor (CVF) to reveal the power of a lens in one material that
would have the same volume and curvature as a lens of another power
in another material.
Of course, prescription labs have fancy software to do such calculations.
But the beauty of Dr. Cook’s method is that an ECP can quickly make the
calculation in their head while the patient is still at the dispensing table.
As he puts it, “By using the CVF, you can balance the increased cost,
reflectance and Abbe (chromatic aberration) issues of higher-index material
against the lower cost, thickness and optical advantages offered by
standard plastic lenses. This CVF multiplier has great potential for helping
you give the very best lens design advice to every one of your patients.”
I bet Napoleon would be impressed.
—Andrew Karp, email@example.com