Recognition Visual Acuity

The recognition (or identification) acuity of a person’s visual system refers to the smallest detail whose form can be recognised.

This type of acuity measured by a standard letter chart. The patient must recognise the letters and identify them correctly.

When the letters reach the limit of the person’s recognition acuity they are too small for the detail within them to be distinguished. At this point, for example, an ’N’ may be indistinguishable from an ’H’.

Younger patients or those with intellectual impairment can be asked to match letters or pictures to achieve a measure of recognition visual acuity. The examiner usually holds the letter at three meters from the child.