Vision screening in New Zealand: an audit of the B4 School Check.

AIMS

To assess the accuracy of the B4 School Check (B4SC) vision screening programme in two distinct regions of New Zealand.

METHODS

A retrospective audit of all children who were screened for vision in the Southern and Tairawhiti District Health Boards, between 1 April and 30 September 2016. Results from the B4SC screening programme (n=2,109) were compared to records for all children who were screened and subsequently presented to an optometrist at a DHB eye clinic (n=116).

RESULTS

The B4SC produced a sensitivity in the range of 54.7% to 94.7% and a specificity of 93.8% to 95.7%. There was a low positive predictive value (PPV), between 29.5% and 51.1%, with a relatively high number of false positive referrals. The negative predictive value (NPV) was higher, however, between 97.8% and 99.7%, meaning nearly all children who passed screening had no visual impairment.

CONCLUSIONS

The high NPV is reassuring that very few children with visual impairment are missed by screening. The low PPV was consistent with the international literature and is related to a tendency for over-referral from the B4CS programme. Further work could evaluate increasing the threshold for referral to reduce the number of false positive cases.