How good are we at assessing driving visual fields in diabetics?

Following laser panretinal photocoagulation (PRP) for proliferative diabetic retinopathy, patients are at risk of failing the UK driving visual field test due to loss of peripheral field. Although a definition of the minimum field requirement exists, differences in its interpretation may influence whether fields pass or fail. Currently it is not known how fields are interpreted in practice nor to what extent this affects failure rates.

Uniocular and binocular Esterman visual fields from 60 diabetic patients following PRP were examined both by the chairman of the Visual Standards Sub-Committee of the Royal College of Ophthalmologists and separately by four consultant ophthalmologists. The results were analysed (1) to assess the extent of agreement and (2) to identify, from the chairman's results, the field deficits that are still compatible with passing.

Agreement was generally good for binocular fields but was only moderate for uniocular fields. In up to 15% of binocular fields and 43% of uniocular fields the chairman's decision was different from that of the consultants. Several key aspects of the field that influence a pass/fail decision are identified.

Substantial differences in the assessment of driving visual fields following RPR currently exist between consultants and the chairman of the Visual Standards Sub-Committee. Using the information presented here to guide assessment it is now possible to reduce this variation.