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After a brief outline of the formation and properties of laser-produced speckles, the paper describes a method of measuring the eye refraction based on the observation that the speckles from an illuminated surface appear to move when the surface and the eye have an angular movement relative to one another. Movements of the speckle pattern in the same or the opposite direction as the apparative movement indicate over- or undercorrection. The results of a simple mathematical theory of the phenomenon, including sensitivity calculations, is given. A test apparatus is described, as well as findings when this is used at a number of subjects.

Titullapā norādīts autors: Apiņš, Kārlis

The history of eye refraction is traced back to the nineteenth century. The modern manual refractor started with DeZeng in 1908. Manual methods are brought up to date with the history of current commercially available refractors. The theory and practice of design of computer-actuated refractors is discussed with particular reference to three new models which have radical deparatures in design compated to manual refractors. Future eye refractors are discussed with particular reference to variable-powered lens systems. The design of crossed-cylinders in computer-actuated refractors is treated.

Since Koch's discovery of tuberculin some seven years ago, we no longer wonder that the majority of medical men were turned away from the employment of this remedy by its ill-advised use, and the resulting gross effects, as shown by Virchow, the great pathologist. From the absurd advertisement of a Swiss barber "tuberculin injections given here," and the equally preposterous belief which at first prevailed that a means to destroy tuberculosis had been discovered, as easy of use as a household remedy, we have come to learn that if cure it will, it must be by a concentration of skilled effort, and a technique involving as much discrimination in diagnosis and care as does the differentiation of a complicated eye refraction, the microscopic determination of blood changes due to disease, the endoscopic study of internal organs, or any other delicate field of professional work. The great mistake of the celebrated