The influence of fixation stability on balance in central vision loss

Background: Some major visual disorders damage the central retina and to compensate for the loss of a functioning fovea, those affected use their remaining peripheral retina to accomplish daily tasks. This results in the formation of an unstable, non-central fixation point, which compromises ability to detect obstacles and acquire visual information from the environment. The purpose of this study was to determine if there is a measurable (and significant) difference in balance ability and fall risk between visually impaired people with stable fixation and those with unstable fixation.

Method: Individuals (n = 44) with a visual acuity of >20/400 in the better eye and a diagnosis of a retinal disorder affecting the macula were recruited for this study. Fixation stability was determined using the Mirametrix Eye Tracker and participants were then divided into two groups: stable fixation and unstable fixation. Functional balance was measured using the Timed Get-Up-and-Go (TUG) and the Berg Balance Scale (BBS). Balance confidence was assessed using the Activities-Specific Balance (ABC) Scale.

Results: Performance on the TUG test was significantly different between the groups, with the poor-fixation group having a slower TUG time than the stable-fixation group, t (42) = −1.763, P = 0.043. Subjects with poor fixation stability scored lower on the ABC scale and on the BBS compared to the stable fixation group, but the difference was not significant.

Significance: Based on the TUG, those with unstable fixation are at a higher risk of falls compared to individuals with stable fixation. Given fixation stability is a visual factor that can be trained and improved upon, these findings warrant further research into the relationship between fixation stability and balance.