The Parsons visual acuity test for screening children 18 to 48 months old.

The Parsons visual acuity test (PVAT) uses modified Allen test targets for visual acuity assessment in young children and persons who are difficult to test. Using this method, we were able to obtain a visual acuity threshold in 44% of 18- to 24-month-old children and in 90% of children aged 25 to 36 months. At all ages tested, the mode for visual acuity was 20/30; however, the percentage of those with 20/20 increased with age. The decision whether to refer was correctly made by means of the PVAT criterion 83% of the time.