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Gang Luo, Eli Peli; Patients with tunnel vision frequently saccade to outside their visual fields in visual search. Journal of Vision 2006;6(6):505. doi: 10.1167/6.6.505.
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© ARVO (1962-2015); The Authors (2016-present)
Peripheral visual information is normally used for planning of saccadic eye movements in visual search. Patients with tunnel vision have severely restricted peripheral visual fields (VF) due to retinitis pigmentosa, choroideremia, etc. It is of interest to investigate how loss of peripheral vision would affect the saccadic eye movements of the patients.
9 subjects with tunnel vision (VF: 8°–16°) performed visual search for “pop-out” targets sequentially presented outside their VF, within a 66°×54°) area, in 4 sessions combining two cue conditions and 2 types of background, with or without auditory cues provided by 8 buzzers that indicated the approximate direction of targets, and over a blank background or a complex background (one of 16 street scene pictures).
We found that the amplitudes of 30% of the saccades were larger than the subject's VF. The frequency of saccades was exponentially distributed with amplitude (for those > 4°), and was very similar to the distribution reported for normally-sighted subjects walking through a college campus (Bahill 1975 Invest. Ophthalmol.). Use of auditory cues or complex backgrounds did not affect the distribution (P>0.46). No effect of VF size on saccadic eye movements was found.
These results suggest that many saccades of subjects were not elicited by visual information. While lacking peripheral vision, subjects probably performed search based on an internal representation of space in mind, by which they voluntarily saccade to locations outside their VF. One of the questions remained to be answered is if this strategy is optimal for people with tunnel vision.
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