Fields, DVLC and panretinal photocoagulation

Laser panretinal photocoagulation (PRP) reduces visual loss in proliferative diabetic retinopathy but decreases peripheral retinal function. The Driver and Vehicle Licensing Centre (DVLC) states that when a patient volunteers that he or she has had photocoagulation, a questionnaire will then be sent to the patient's diabetic physician who can refer the patient for formal field testing. Of 30 patients who had PRP, 15 failed DVLC visual field regulations using the Esterman binocular field test on the Humphrey field analyser. The failures were more likely to have had treatment with a xenon laser, but there was no difference between the groups as regards age, number of burns or whether an argon or diode laser was used. The patients who failed were more likely to be hypertensive (p = 0.04). Two patients with unilateral PRP could not meet the driving regulations because of other field defects. Diabetes itself causes field defects, and therefore even with small amounts of laser, formal field testing may be necessary.