To the Editor.
—In the April Archives (1983;101:665), Gamel and Eiferman drew attention to corneal burns and cataracts caused by argon laser therapy with the Rodenstock Panfunduscopic lens. When analyzing possible causes, they missed the explanation given by Birngruber et al,1 which is based on the optics of the Panfunduscope. While a focused beam through a Goldmann lens has its smallest diameter at the retinal plane, a properly focused beam with a Panfunduscope has the narrowest beam distribution just anterior to the cornea. This results in a high energy concentration in the cornea, the iris (if the pupil is not well dilated), and the lens. In the lens, the focal energy concentration is still about 25 times higher than in the retina.
Teichmann KD. Cataracts Produced by Argon Laser Photocoagulation. Arch Ophthalmol. 1983;101(12):1948. doi:10.1001/archopht.1983.01040020950026