Diabetic patients must also satisfy regulations

EDITOR,—Potamitis and colleagues draw attention to the low level of awareness among patients with glaucoma of their legal requirement to inform the Driver and Vehicle Licensing Agency of their condition.1 The agency's regulations also require diabetic patients to have their binocular field of vision assessed if they have declared that they have undergone laser treatment. Treatment for proliferative retinopathy often requires the application of laser beams to all retinal areas outside the macula; this can have a severe effect on the patient's visual field. In one study 15 of 30 patients treated with panretinal photocoagulation failed the agency's regulations regarding visual fields.2 Other investigators, however, have found that if a laser beam spot of smaller diameter is used less loss of visual field occurs.3

In her commentary on Potamitis and colleagues' report Margaret Hawkins states that patients with glaucoma at any stage must notify the Driver and Vehicle Licensing Agency.1 She also declares that “failure to advise their patients correctly may render doctors liable to litigation.” The same rules thus apply to diabetic patients who have undergone laser treatment. The only way accurately to advise patients with diabetes or glaucoma of their legal driving status (and thereby avoid possible litigation) is to plot their binocular visual fields. This test is not routinely done in the management of patients with either diabetes or glaucoma, and thus to implement it would pressurise an already overtaxed facility. It would also lead to an increased interval between routine tests of visual fields, which are required for the management of glaucoma. This might compromise the care of patients with glaucoma. Alternatively, new staff would have to be recruited to take on the increased workload.