PubMed · 6643896
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S J Baron. 1983. High myopia.. https://pubmed.ncbi.nlm.nih.gov/6643896/
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Spectacle corrections worn in a frame with a faceform tilt should be used with effective spherocylindrical parameters. For the case of oblique central refraction, Keating presented a procedure to determine these parameters in a third-order approximation. The central equation of his approach, the effective dioptric power matrix, is partly the result of an educated guess. Based on the equations of wavefront tracing, an analytical derivation of his equation, slightly modified however, is given in this paper.
Eyeglass lenses are commonly composed of allyl-diglycol carbonate (CR-39), an alpha-particle detecting plastic, thus making such lenses personal radon dosemeters. Samples of such lenses have been obtained, etched to reveal that radon and radon progeny alpha tracks can be seen in abundance, and sensitivities have been calibrated in radon chambers as a primary calibration, and with a uranium-based source of alpha particles as a convenient secondary standard. With one exception natural, environmental (fossil) track densities ranged from less than 3,000 to nearly 70,000 per cm2 for eyeglasses that had been worn for various times from one to nearly five years. Average radon concentrations to which those wearers were exposed are inferred to be in the range 14 to 130 Bq x m(-3) (0.4 to 3.5 pCi x l(-1)). A protocol for consistent, meaningful readout is derived and used. In the exceptional case the fossil track density was 1,780,000 cm(-2) and the inferred (24 h) average radon concentration was 6500 Bq x m(-3) (175 pCi x l(-1)) for a worker at an inactive uranium mine that is used for therapy.