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, akarp@jobson.com