The IVEX refraction system: a clinical comparison.

A new refraction system employing traditional modes of testing combined with microprocessor-based electronics and new optical technology was evaluated in a controlled study to determine if the instrument produced subjective refractions corresponding to the traditional refractor. Subjects ranged in age from 14 to 25 years and the study excluded any individual exhibiting ocular or systemic diseases and binocular problems. In addition, tests were made to determine if "instrument myopia" was present. The results showed that data from the IVEX Refraction System correlated highly with data from the standard refractor, but a small amount (0.25 D to 0.37 D) of instrument myopia was present in most instances.