[Case finding of amblyopia in young children using the TNO-depth-vision-test]

To evaluate the policy in amblyopia detection by pre-school health care workers we studied the prevalence of amblyopia that had not previously been detected among 1975 children at the ages of 4 years 6 months to 5 years 10 months. Seventy-eight (3.9%) of the children had insufficient stereo-acuity, though no form of ocular abnormality had been noted in the past. Twenty-one (1%) of the children had a previously undetected amblyopia. After 1 1/2 years 74% of the children with amblyopia had a visual acuity of 0.9 or more, while most of the children--at the time of referral--were 4 1/2 years or older. Amblyopia can be identified earlier by (a) a proper transfer of information from pre-school health care workers to the school doctor; (b) taking into consideration low vision if assessment of vision was not successful in the first examination, and (c) performing at least the TNO-stereotest when in doubt.