Measuring oculomotor stability during the assessment of image distortions with Iterative Amsler Grid (IAG) I Ayhan1, T Holmes2, J Zanker3 |
|---|
1Department of Psychology, Royal Holloway, United Kingdom |
| Metamorphopsia is experienced in age-related macular degeneration (AMD), as the perceived distortions of straight contours. The standard clinical tool to assess metamorphopsia is the printed Amsler Chart, a grid of equally spaced horizontal and vertical lines, in concunction with patients' report of deformed and irregular appearance. We developed an iterative procedure (IAG), to obtain a reproducible map of visual deformations. Curved horizontal and vertical lines segments (perceived or physical distortions) are displayed on a computer monitor to probe different regions of the visual field and then manipulated by observers such that they appear straight. Control participants were able to reliably correct deformations that simulate metamorphopsia. Pilot experiments involving AMD patients suggest that they are comfortable using the IAG method and generate sensible deformation maps, but also indicate that stabilising gaze can be difficult for them. In our current work we measure the gaze positions of control participants (Tobii X120 eye tracker). We observe that in the IAG the ability to maintain fixation in the centre of the display varies with the distance to the adjusted segment, suggesting that the gaze control can be reliable enough to manipulate lines in extra-foveal positions, to assess distortion maps in the central visual field. |
| Up Home |
|---|