Clinical study of low vision. Part I: Refraction and the aided distance vision

Eighty three cases of low vision patients (144 eyes) were examined with distant visual aids. The average visual acuity of the 144 eyes before refraction was approximately 0.07, while the counterpart afterwards was about 0.1 (p less than 0.01). With the 4x monocular focusable aid, acuity improved in 142 eyes out of the 144 eyes. The combined use of clip-on distance aid and the spectacle reading aid was observed to be especially suitable for partially sighted students. The mean MEF of 142 eyes was 0.9435 +/- 0.2068. The paired T-test between the difference of actual magnification and theoretical magnification was not significant at the 5% level. The factors contributing to the variance of MEF were discussed.