The measurement of the amplitude of accommodation and convergence, and of the relative range of accommodation and convergence; does not receive, in routine practice, the attention that its importance demands. This neglect is due, partly, to a lack of appreciation of the significance attached to the data furnished by such measurements, and, partly, to the fact that a low-priced practical ophthalmodynamometer is not to be found on the market.
The accurate measurement of the relative range of accommodation and convergence is a difficult and tedious laboratory process requiring an expensive apparatus, great precision and expertness on the part of the operator, and more than ordinary powers of observation on the part of the patient.
Fortunately, for ordinary office practice, such exact measurements are not necessary; but decidedly more accurate work is required than it is possible to accomplish with the usual test-card and tape measure.
The apparatus herewith presented was