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Medicine: From the Lighthouse

2 minute read

Augustin Jean Fresnel lost his job as an engineer with the French government in 1815 because he opposed Napoleon’s return from Elba. Then he turned his fertile, inventive brain to the problem of getting lighthouses to give more light. Little recognized in his short (1788-1827) life, Fresnel (pronounced Fray-nell) wrought an optical revolution and indirectly saved untold lives by junking the mirrors on which lighthouses had long depended, instead put the light source inside a cylindrical lens with multiple-refracting bands at top and bottom. The resulting Fresnel lens (commonly pronounced Frez-nel) still has many maritime uses, is on sale by most ship chandlers.

Last week Manhattan’s equally fertile and inventive Optometrist William Feinbloom (TIME, Jan. 2, 1933 et seq.) told a Buffalo gathering of optometrists how he had adapted the Fresnel lens to make trioptic spectacles for the near-blind. Feinbloom has concentrated for decades on the problem of 500,000 Americans who are legally blind (less than 10% useful vision), but who could read and work if only they could get the right glasses. Previous Feinbloom inventions supplied correction for only one focal range (close work such as reading and sewing, middle range for dressing and household tasks, or distance for outdoors), and the patient had to keep switching three pairs of glasses. Each pair was expensive, so the benefits of Feinbloom’s ingenuity could not reach the needy blind.

Feinbloom’s new device is a three-in-one, like the executive’s trifocals. Most of the field (both sides and the middle) consists of plastic with no magnification, corrected only for distortion caused by the refractive errors in the patient’s eye. This is for middle distance—3 to 25 ft. At the top is a thick oval lens, apres Fresnel, with three-power magnification for distance—”infinity,” which begins at 25 ft. At the bottom is a similar lens with magnification of 3 to 20 diameters for reading, sewing or benchwork. Cost of the three-in-one lighthouse: $250 to $300.

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