FLASH AND PATTERN VISUAL-EVOKED POTENTIALS IN THE DIAGNOSIS AND MONITORING OF DYSTHYROID OPTIC NEUROPATHY

Flash and pattern visual evoked potentials were recorded in 8 patients (13 eyes) with dysthyroid optic neuropathy (DON), diagnosed using the American Thyroid Association classification, All were treated with sy stemic steroids, but 4 patients (6 eyes) also required orbital decompr ession, Flash VEP (P2) and pattern VEP (P100) were recorded prior to a nd 2 weeks after commencing steroid treatment or decompression, Fiftee n patients with Graves orbitopathy but without DON, and 20 healthy sub jects, acted as controls, Before treatment visual acuity was reduced i n 10 eyes and visual fields were abnormal in 5, but the VEP was abnorm al in all 13, with the group mean amplitude of P2 and P100 significant ly less than controls, and the group mean P100 latency significantly g reater than controls, After treatment with high-dose steroids or surgi cal decompression there were significant improvements in the group mea n amplitude of P2 and P100, and significant reductions in P2 and P100 latency; however, individually, improvements in amplitude were more si gnificant than improvements in latency, We conclude that the VEP to fl ash and pattern stimuli provides a useful diagnostic and monitoring to ol in patients with DON, combining objectivity with quantitative analy sis.