The Cardiff Near Test - How It Works

Like its ‘sister’ test, the Cardiff Acuity Test, the Cardiff Near Test uses vanishing optotypes. The targets are drawn with a white band bordered by two black bands, each of half the width of the white band, all on a neutral grey background; thus the average luminance of the target is equal to that of the grey background. If the target lies beyond the subject’s acuity limit, it merges with the grey background, and simply becomes invisible.

The benefit of the vanishing optotype is that the test is considerably more sensitive to blur than is a conventional test. The end-point is therefore sharper and the test should allow relatively small deficits in accommodation or focusing to be picked up. Further, when the targets of a vanishing optotype are beyond the acuity limit, they are invisible. A child proceeds along the test until no more pictures are visible. A child with poor vision may only identify the larger targets, but he/she has no idea that there are smaller targets on the card. This avoids the sense of ‘failure’ inherent in other acuity tests in which the child can see further rows of targets but cannot discriminate the detail. The Cardiff Near Test is therefore particularly useful for children with intellectual disabilities who may have low self-esteem.

The targets used are pictures, decreasing in overall size, and in width of the white and black bands. The acuity is given by the narrowest white band for which the target is visible.

How to carry out the test

There are two test cards and one matching card. Present the matching card to the child first, and determine whether the child can name or sign the pictures, or will match. The matching card is used initially to familiarise the child with the concept of the test and to build confidence.

Then present the first of the two test cards (with the larger pictures), at a distance of 33cm from the child’s eyes. Ask the child to name, sign or match each picture. Proceed to the second card. As with standard tests, the end-point is the finest picture that the child can recognise correctly.

You may want to intersperse 'easy' pictures (i.e. return to a larger line) with ‘harder’ ones, to keep a child’s motivation. At the end of the test, return to a larger picture size and allow the child to identify all correctly – always end on a success.