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Measures of visual function in minimum datasets
  1. Great Ormond Street Hospital for Children
  2. 30 Guilford Street
  3. London WC1N 1EH

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    Editor—We strongly support Johnson’s recommendation for a standard minimum dataset for follow up studies,1 which includes information on visual function. There are very limited data available on the incidence of severe visual impairment and blindness among children in the UK. Estimates have often been based on the national registers of partial sight and blindness. However, these have documented limitations in terms of detail and completeness and can only provide rates of registration of visual deficit.2

    We understand the rationale for a minimalist approach to collection of readily available data, but propose an alternative to the suggestion of recording only whether the child is blind or sees light. Blindness can be difficult to define and measure in young children. Even among children at high risk of severe visual defects, inability to perceive light and other levels of blindness3 are not common. Moreover, blindness per se is not always the outcome of greatest interest. We therefore suggest that the ability to fix and follow a light should be recorded. This can be assessed in most young children, including those with other disabilities.

    If a less minimalist approach to the minimum dataset were adopted, particularly for older children, the corrected visual acuity in each eye, together with the method of measurement, should be recorded. This information should be readily available for children thought to have a visual defect as they are likely to have undergone an ophthalmic assessment. This would improve the comparability of follow up studies and their usefulness in planning educational and other services without unduly expanding the minimum dataset.

    Finally we suggest that whether the child has been registered as partially sighted or blind should be recorded. We believe that these refinements of the proposed measure of visual function would improve the usefulness of routinely collected data on visual morbidity among children at high risk of visual defects.