A Remote Subjective Refractor Employing Continuously Variable Sphere-Cylinder Corrections

At the present time, the preferred method of determining optical corrections suitable for prescribing optical aids such as spectacles is through subjective response of the individual being examined. Instrumentation for this purpose has been basically unchanged over the last forty years. New types of optical components and optical systems are now available that promise to increase the ease and reliability of such subjective refractive determinations. One such system incorporating the recently developed variable power spherical and astigmatic lens systems results in a particularly convenient form of subjective refractor, which is described in this article.