Accommodation During Observations with Optical Instruments

Abstract

Persons looking through optical instruments fitted with eyepieces tend to accommodate. This accommodation, termed instrument myopia (IM), is influenced by a variety of parameters. IM varies in general from 0.5 to 3 diopters for stereoscopic viewing. With monocular instruments it is about 1.5 diopters greater. The IM of each observer is rather constant; its fluctuations are proportional to the amount of IM measured. IM also depends on the way of focusing. Image configuration and contrast, magnification, and luminance seem to be of minor influence.