Validation of physiologic predictors of successful telescopic spectacle use in low vision.

A group of 32 patients with low vision who were considered clinically appropriate candidates for visual rehabilitation with telescopic spectacles were prospectively studied before the first attempted use of these visual aids. Laboratory measurements were made of: (1) rotational head stability in pitch and yaw during quiet standing; (2) sensitivity of visual acuity with telescopic spectacles to imposed yaw head motion; and (3) ocular stabilization reflexes during passive, whole-body rotation in the horizontal plane. Predicted likelihood of successful use of telescopic spectacles was prospectively computed for each patient using the measurement of head stability in the pitch axis and the sensitivity of visual acuity with telescopic spectacles to head motion using a previously described statistical method. Patients were then given telescopic spectacles, and functional success was evaluated in the field at least 6 weeks later by independent masked observers. Although corrected visual acuities did not differ in the 24 patients in whom rehabilitation was successful or in the 8 patients in whom it was not, successful patients had statistically significantly less (P less than 0.05) angular head instability in pitch and yaw, as well as less impairment of visual acuity with telescopic spectacles during head motion. This finding was confirmed in a more clinically homogeneous subgroup of 16 patients who had low vision due to maculopathy. Gains of the 0.1 Hz horizontal vestibulo-ocular reflex (VOR) and visual-vestibulo-ocular reflex (VVOR) with 4X telescopic spectacles did not differ between patients in whom rehabilitation was successful and those in whom it was not.(ABSTRACT TRUNCATED AT 250 WORDS)