Spherical refraction for general eye workers.

Many people coming to eye clinics have refractive errors and can have their vision improved by spectacles (glasses). Most of these can be tested by general eye health workers without special training and using only a trial set of lenses. It is also useful to find out quickly which people do not have refractive errors and do not need glasses. Most errors can be corrected satisfactorily with spherical lenses that can be obtained cheaply. Not many have important astigmatic errors needing cylindrical lenses. The simplest method is to have a range of spectacles and let the person try them on, but this can be misleading. This article describes methods that are both simple and accurate.