Rapid and precise assessment of the temporal contrast sensitivity function on an iPad M Dorr1, L Lesmes1, Z-L Lu2, P Bex3 |
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1Schepens Eye Research Institute, Harvard Medical School, MA, United States |
| The natural world can be highly dynamic, and the temporal contrast sensitivity function (tCSF) therefore describes a fundamental component of real-world vision. Its high-frequency cutoff corresponds to critical flicker fusion, and changes in the tCSF can be clinically diagnostic for a variety of neurodegenerative eye diseases such as glaucoma or AMD. We have implemented a rapid and precise test of the tCSF on the iPad, based on the qCSF family of adaptive behavioural measurements [Lesmes et al, JoV 2010]; the tCSF is described by only four parameters and stimulus selection maximizes the expected information gain for each trial, reducing the number of required trials for full tCSF characterization to only 15-30 in a 10AFC task. Because of the known issues with temporal properties of digital displays [Elze, J Neurosci Methods, 2011], we carefully evaluated the iPad display with an Optical Transient Recorder. We found strong nonlinear effects that depend on contrast level and frequency, and that need to be compensated for during stimulus selection and display. Combined with previous work on precise assessment of the spatial CSF [Dorr et al, ECVP 2012], our test battery on the iPad platform now allows full characterization of visual sensitivity outside the laboratory. |
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