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Joseph M Miller, Howard P Apple, Tina K Green, Deborah Apple, Erin M Harvey; The Dobson Card: An electronic display for forced-choice preferential looking (FPL) assessment of infant and toddler visual acuity. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2921.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if the looking behavior of infants and toddlers during Acuity Card Procedure (ACP) testing using electronic stimuli is similar to the behavior observed when printed stimuli are used.
A trained and experienced Teller Acuity Card tester measured binocular grating acuity in 8 subjects aged 9 to 45 months. Stimuli were presented using The Dobson Card (DC), a hand-held matt-black plexiglass frame (10”x22”) that flush-mounts 2 Google Nexus-7 (N7) tablet computers to the right and left of a center peephole. One tablet displays a square wave grating (1/2 octave steps), the other a luminance-matched gray patch. Stimuli were generated using Java language. An experimenter luminance matched the 2 tablet gray patches, then matched gratings to the paired gray patch. The gray patch and paired grating had a luminance of 92 lux, and widest white stripe 170 lux (Dr Meter LX1330B photometer). An assistant controlled the tablet displays via Bluetooth to preserve tester masking of grating location and permit standard ACP testing. The DC was presented in a ACP stage (Vistech Consultants).
All subjects looked at the gratings in a manner similar to TAC. However, observed acuities were low normal/below normal when compared to published norms obtained with the printed Teller Acuity Cards (Vistech Consultants, Inc., TAC II now manufactured by StereoOptical). Acuity ranged from 2.4 to 18.2 Cy/Deg (cpd), median 5.65 cpd, mode 4.8 cpd.
Children exhibit interest in viewing patterns of black and white stripes over gray control stimuli presented using tablet computers set against a black background in a manner similar to printed gratings against a gray background. The tasks differ, as the tablet requires comparison and cards detection. Acuities were below those expected for children of the same age using printed stimuli. Further work is required to determine the optimum stimulus luminance and background illumination, and normative data for DC acuity will need to be generated. Previous work has shown that even different versions of printed acuity cards yield different norms (Vistech vs Stereo Optical cards, Haynes et al., ARVO 2004). While static square wave gratings are used in this initial evaluation, the Dobson Card can be used for the display of a variety of stimuli such as alternating checkerboards or displays of coherent motion vs random motion.
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