City Gratings Acuity Flip Test
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The City Gratings Cards have been developed by a team of clinical vision scientists at City University to provide a rapid means of assessing infant visual acuity.
The cards make use of an established and validated assessment technique known as the “acuity card procedure” whereby an infant’s innate visual tendency to fixate patterned, rather than homogenous objects in their environment, is exploited to obtain a quantitative estimate of visual acuity. This new version is more convenient to use in that it is lighter in weight and more compact. It can be carried around easily. The flip format allows the tester to easily prepare the cards for the next test without the time consuming task of rearranging the cards in order and replacing them in the box. The test can be used with the “A” shaped display stand allowing the tester to sit behind the unit while the child sits opposite with mum or dad. |
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This simple-to-use test, involves presenting an infant with a series of card-mounted grating patterns differing in spatial frequency (fineness / coarseness) and observing their looking behaviour through eye movement across the card. Each grating is paired with a similarly sized, grey, “blank” pattern of the same brightness. The examiner determines whether a looking preference exists for a given grating and if it does, the infant can be presented with further cards with gratings of increasing spatial frequency until the infant’s acuity limit is reached i.e. they no longer exhibit a preference for the grating. The City Gratings cards offer several refinements over other similar preferential-looking based tests: they are scaled using the logMAR approach (considered the most appropriate for visual acuity testing) and are small and lightweight facilitating their use across multiple locations." |
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