Purpose:
To investigate the effect of glaucomatous visual field loss on static balance.
Methods:
Patients with glaucoma (n=10, mean [SD] age, 71.1 [12.4] years) and asymmetric visual field damage (MD, -1.9 [2.3] dB in better eye, -12.9 [3.4] dB in worse eye) were recruited from the glaucoma clinics at the QEII Health Sciences Centre in Halifax, Nova Scotia, Canada. Static balance was measured with the Equitest (Neurocom Inc, OR). Somatosensory proprioceptive feedback was reduced by having patients stand on an unstable support surface that would actively tilt to follow the anterior-posterior body sway. Thus, clues for maintaining balance were mainly visual and vestibular. Data were obtained with both eyes open, the better eye open, the worse eye open, and with both eyes closed. For each condition, 3 runs of 20 s each were performed. Postural sway was expressed as the root-mean-square (RMS) of the centre-of-gravity distribution.
Results:
Postural sway increased with age, by approximately 40% per decade [95% CI, 14-59%]. Eight of 10 patients appeared less stable when the better eye was closed. Sway was substantially greater with the worse eye than with the better eye (mean increase, 32% [95% CI, 4-60%], p=0.04). There was no significant increase in sway compared to the binocular condition when the worse eye was closed (mean increase, 13%; [95% CI, -11-38%], p=0.23).
Conclusions:
Patients were less stable when they used the eye with more extensive visual field loss. This suggests that paracentral and peripheral vision may be more important to postural stability than previously thought. Further work needs to determine to what extent reduced balance contributes to the increased risk of falling in glaucoma. Between-eye comparison may provide a powerful approach to investigate the impact of glaucoma-related visual loss on real-world performance.
Keywords: visual fields • quality of life • perimetry