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Iliya Ivanov, Annika Vollmer, Nhung Nguyen, Susanne Trauzettel-Klosinski; Is visual exploration training beneficial in tunnel vision?. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2769.
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© ARVO (1962-2015); The Authors (2016-present)
Tunnel vision is a severe peripheral visual field loss impairing mobility. It has been previously shown that normally sighted subjects exhibit larger horizontal than vertical component of eye position dispersions (standard deviations) while walking and avoiding obstacles in daily life. However, for patients with tunnel vision caused by retinitis pigmentosa (RP), horizontal and vertical components were not found to be significantly different 1. In this study we wanted to test whether visual exploration training is beneficial for RP patients, as in patients with homonymous hemianopia 2. Any efficient eye movement training in RP patients, would result in change of eye-movement pattern- larger horizontal than vertical dispersions.
Patients (n=33) were randomly assigned into three training groups: saccadic (experimental), reading (placebo) or crossover (placebo+experimental). In saccadic training condition, computer-based training extended eye-movement exploration outside of the concentric constriction of the visual field (VF). In reading training condition patients had to read a text that was presented at the center of the screen, one word at time. To assess any effect of training, mobile eye tracker was used to record eye positions while walking in standardized environment (parkour), before and after training. We compared horizontal and vertical eye dispersions of patients in the different experimental groups with a control group of normals (n = 10).
Comparable with previous findings, patients who had residual VF < 15° (from fixation) showed equal horizontal and vertical dispersions before training. After training however, patients who received saccadic training showed significantly larger horizontal dispersion (p<0.05). Patients with VF > 15° remained the same. Regardless of their residual VF, patients in placebo group did not show an effect of training: horizontal and vertical dispersions remained unchanged after training.
These findings suggest that visual exploration training is highly specific and resulted in significantly increased dynamic VF for the RP patients with VF < 15°.
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