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One in three glaucoma patients experiences an injurious fall over a one year period, making it a priority to understand the reasons behind these falls. One potential reason for falls is poor balance, motivating Kotecha and colleagues to compare balance in 24 glaucoma and control subjects. Balance was evaluated using a force plate measuring the center of foot pressure displacement and was completed on both firm and foam surfaces (the latter to eliminate somatosensory inputs), and with eyes open or closed (the latter to eliminate visual inputs). The authors found that balance did not differ between glaucoma and control patients (or with severity of VF loss) in any of the four conditions tested. However, glaucoma patients demonstrated a lower visual contribution to balance, as judged by balance differences under eyes open and eyes closed conditions. The visual contribution to balance also decreased with greater levels of VF loss. On the other hand, glaucoma patients had a greater somatosensory contribution to balance, as judged by the differences between firm surface and eyes open foam surface testing.
One's field of vision is an important component of postural balance, and that there are redundant systems for maintaining postural balance which become particularly critical to balance in glaucoma patients with visual field loss
The authors' findings differ somewhat from previous studies suggesting that postural balance is worse with glaucoma patients. No such effect might have been found in the current study because of differences in the age distribution of the study populations, small sample size, or recruitment of particularly fit glaucoma subjects. Indeed, the glaucoma patients in the current study had slightly better balance in eyes open firm surface testing than controls. Overall, the authors' findings support the idea that one's field of vision is an important component of postural balance, and that there are redundant systems for maintaining postural balance (vestibular, somatosensory) which become particularly critical to balance in glaucoma patients with visual field loss.