The punctumeter is an instrument for ascertaining the range of accommodation. Its name signifies a point-measurer, i. e., to measure the far and near points of vision. The difference between these two points equals the range of accommodation. For several years I have been impressed with a lack of reliable methods for making these measurements. No instrument for obtaining this information being in existence, I began to study whether it would not be possible to have one constructed on scientific principles. After the usual history of trials and failures I am at last able to present to the profession an instrument which I believe to be absolutely reliable. It is so constructed that it can also be used as a rapid test for any of the errors of refraction and in this respect I know of no instrument that is superior to it.
A 10 D. convex lens is placed