The Cardiff Acuity Test® is designed specifically for acuity measurement in children aged 6 months to 3 years. The test may also be helpful with other age groups with intellectual impairment, dementia, head injury or stroke. Other versions are available for contrast, near point, and special needs testing which employ similar techniques.

TEST PRINCIPLES

The test employs the principle of vanishing optotype, in other words the figure (fish, car etc.) blends with the gray background shades at the acuity threshold. Thus resolution, detection and recognition acuity thresholds are all brought together. The target figures are pictures, all of the same overall size, drawn in decreasing widths of white and black lines. Acuity is determined by the narrowest white band for which the target is visible to the child.

As the examiner shuffles through the cards, the movement of the child's eyes up or down is noted.

The vanishing optotypes are combined with the principle of 'Preferential Looking' to provide a pediatric test method that provides excellent accuracy of diagnosis. When a card is presented 

the child will choose to look towards the top or bottom of the card if they have sufficient acuity to

recognize the target figure. This works because the child naturally prefers to look at a target figure rather than the blank end of the stimulus. Further, 'Preferential Looking' works when the examiner does not know whether the top or the bottom of the cards contains the target figure. If the child does not show a preference for either the top or bottom of the card, the acuity threshold has been exceeded.

Set includes cards, Carrying case, instructions and Butterfly occluding glasses

TEST ADMINISTRATION

The Standard Cardiff Acuity Test includes three cards at each acuity level. Cards can be used at either one meter or ½ meter. The Richmond P/N 4740R Standard card set includes 36 cards providing 24 acuity levels when used at both distances. Thus they cover acuity levels from 20/320 to 20/12.5 (6/96 to 6/3.75). Richmond P/N 4741R Low Vision Cardiff Acuity Set adds three levels of acuity and therefore covers 30 levels (45 cards) when used at both distances and extends acuity levels up to 20/640 (6/192) . These nine Low Vision cards are also available separately as P/N 4754R.

A working distance of 40 inches (one meter) is recommended. At this distance eye movement position judgements are reliable and a range of 20/160 to 20/12.5 (6/48 to 6/3.75) can be measured with the Standard Set. A closer working distance of 20 inches (50 cm) can be used as an alternative to test lower acuity levels or allow closer interaction with the child.

The Cardiff Test employs an up-down positioning of the target figures rather than the right-left separation (as is used in the Teller Acuity Cards® II) so that the eye movements are easier to discriminate in cases of congenital nystagmus. Further, the Cardiff Test can be used in cases of suspected malingering as the patient's eye movements are involuntary. Administering the Cardiff Acuity Test is relatively quick and easy to learn. On average, an experienced examiner can conduct a complete test in 3-5 minutes.

The standard Cardiff Acuity Test kit includes 36 cards and Butterfly occluding glasses. Card measure 7 ¾ by 10 ½ in (20 BY 27 cm) and are labeled by acuity level equivalents in decimal, meters, feet, Snellen and LogMAR for both test distances.

Cardiff Acuity Test Norms

4740R   Cardiff Acuity Test, Standard Set with 36 cards & occluding glasses .......... $1,200.00

4741R   Cardiff Low Vision Acuity Test with 42 cards & occluding glasses ............... $1,600.00

4754R   Cardiff Low Vision Upgrade Set ..................................................................... $400.00

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