The Bradford Visual Function Box can predict visual acuity in children who are hard to test.

Abstract

Clinical relevance: Children with special educational needs can find it difficult to engage with traditional visual acuity testing methods; nonetheless, estimates of visual function are key to understanding how a child uses their vision for learning. Appreciating how functional vision testing relates to clinical scores is essential.

Background: The Bradford Visual Function Box (BVFB) has been shown to be useful in estimating visual function in children who cannot participate in standard acuity tests. How outcomes of the BVFB relate to clinical acuity scores has yet to be determined.

Methods: Retrospective clinical data of 79 children attending special schools were analysed, with particular attention to repeated visits over 7 years. At each visit, vision was awarded one of four classifications: normal, low vision, sight-impaired, and severely sight-impaired.

Results: Overall, 31 children were assessed with the BVFB on at least one occasion, of whom 16 went on to participate in a conventional test on a later occasion. Nine children achieved the same classification with a conventional test as with the BVFB, four were under-estimated by BVFB and three were over-estimated.

Conclusion: The BVFB is a useful tool to predict future visual potential of a child who has yet to develop skills to engage with formal acuity testing. Formal visual acuity testing should be pursued as the child develops as over time, as most children were able to engage with more complex testing regimes.