Binocular balance validity: a comparison of five common subjective techniques.

For most patients, one of the last steps in the subjective determination of the refractive error is the equalization of their accommodative stimuli. Several previous authors have stated that the preferred method of balancing is by some form of binocular stimulation, either with a Turville infinity balance or a polarizing technique [Miles, P. (1948) Am. J. Ophthal . 31, 1460-1466; Morgan, M. W., Jr (1949) Am. J. Optom . 26, 231-239; Goodwin, H. E. (1966) Optom . Wkly 57, 28, 47-51; Grentsch , L. W. and Goodwin, H. E. (1966) Am. J. Optom . 43, 658-663]. This experiment looks at a slightly different aspect: how repeatable a given technique is. We performed five common methods of balancing: vectographic , equal acuity through low plus blur, red-green equalization, Jackson cross-cylinder, and equal loss of acuity with plus blur. We find no significant differences in the variation of any of these techniques; they are all equally reliable. In addition, there seems to be no difference in their mean values, contrary to previous reports.