Gaze and pupil changes during navigation in age-related macular degeneration.
BACKGROUND
The central visual field is particularly affected in age-related macular degeneration (AMD), and this can impinge on a variety of functional tasks, including navigation, which can affect activities of daily living. It has been difficult to assess navigational function under standardised conditions. The aim of this study is to examine gaze function and pupil diameter during navigation in patients with AMD.


METHODS
This study was designed as an observational case-control investigation. 34 patients with AMD and 23 controls were recruited. We simulated a walking journey using video projection and monitored patients using automated eye tracking. Visual acuity, fixation count, fixation duration and pupil diameter were recorded while subjective measurements included recorded voice comments.


RESULTS
The pupil diameters were significantly greater in the AMD group compared with the control group in both easy and difficult segments of navigation (p=0.002). Fixation counts were significantly higher in the AMD group during difficult segments of navigation (p=0.001). The differences in both pupil diameter and fixation count correlated with subject visual acuity.


CONCLUSIONS
Fixation count is a marker of difficult navigational environments in patients with AMD. The combination of video projection and eye tracking to assess visual navigation function is a useful clinical tool and an adjunct to current investigation tools in AMD intervention studies providing objective clinical measures under standardised settings.
School of Built Environment, Heriot-Watt University, Edinburgh, UK.
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PA
Aspinall
Princess Alexandra Eye Pavilion, University of Edinburgh, Edinburgh, UK.
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Borooah
Sultan Qaboos University, College of Engineering, Department of Civil and Architecture Engineering, Muscat, Oman.
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Al Alouch
School of Built Environment, Heriot-Watt University, Edinburgh, UK.
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J
Roe
Princess Alexandra Eye Pavilion, University of Edinburgh, Edinburgh, UK National Healthcare Group Eye Institute, Tan Tock Seng Hospital, Singapore, Singapore.
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Laude
School of Built Environment, Heriot-Watt University, Edinburgh, UK.
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Gupta
NHS Greater Glasgow and Clyde, Stobhill Hospital, Glasgow, UK.
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M
Gupta
School of Built Environment, Heriot-Watt University, Edinburgh, UK.
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Montarzino
Princess Alexandra Eye Pavilion, University of Edinburgh, Edinburgh, UK.
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B
Dhillon
D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology*; D008297:Male; D011680:Pupil / Q000502:physiology*; D014785:Vision, Ocular; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*; D016138:Walking / Q000502:physiology*
Degeneration; Diagnostic Tests/Investigation; Macula