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Anabel Martin-Gonzalez, Ines M. Lanzl, Ramin Khoramnia, Nassir Navab; Evaluation Of Hybrid Magnification For AMD Patients With An Eye-Tracking Based Simulation System. Invest. Ophthalmol. Vis. Sci. 2011;52(14):389.
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To evaluate performance of a hybrid magnification approach developed for a head-mounted display (HMD) as a vision enhancement device for patients with age-related macular degeneration (AMD), by means of an eye-tracking based AMD simulation system.
The system combines an eye tracker, an external monitor, and a workstation. The hybrid magnification proposed consists of a radial linear magnification surrounded by a constrained radial non-linear magnification enclosing an interpolation of hidden information lying below the magnified area. The experiment consists of simulating central vision loss (central scotoma) while reading a short text or following a route on a map assisted by a magnification mode (hybrid vs. linear). The eye tracker obtains gaze position on the monitor where scotoma and magnification center should be displayed. Three scotoma sizes were simulated for reading and only one for following routes (3 texts and 2 routes per mode). Task completion time was measured and analyzed.
In total, 25 volunteers of 20/20 vision performed the experiment. The scotoma sizes were 0.5º, 1.3º and 2.1º visual angles. The median value shows that a subject read 1.3 times faster with hybrid than with linear mode (min 0.9, max 2.4), and followed routes 1.5 times faster with hybrid mode (min 1.1, max 2.6). Gaze tracking permitted a natural eye movement for performing the tasks. The figure shows the HMD system for AMD patients (left) and the simulation system (right). Qualitative feedback of volunteers shows that the global context of the scene (no-hidden information) supported by the hybrid mode provides an efficient spatial orientation.
An eye-tracking based simulation system for evaluating performance of a hybrid magnification for assisting AMD patients was developed. The hybrid magnification improves reading speed 1.3 times and spatial orientation within complex environments 1.5 times. An eye tracker based HMD is required to display the magnification in the preferred retinal locus of a patient.
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