title: Evaluation of multifocal visual evoked potentials in patients with Graves' orbitopathy and subclinical optic nerve involvement.
abstract: Dysthyroid optic neuropathy is the most serious, although infrequent (8-10 %) complication in Graves' orbitopathy (GO). It is known that early stages of compressive optic neuropathy may produce reversible visual field defects, suggesting axoplasmic stasis rather than ganglion cell death. This observational, cross-sectional, case-control study assessed 34 consecutive patients (65 eyes) with Graves' hyperthyroidism and longstanding GO and 31 age-matched control subjects. The patients' multifocal visual evoked potentials (mfVEP) were compared to their clinical and psychophysical (standard automated perimetry [SAP]) and structural (optic coherence tomography [OCT]) diagnostic test data. Abnormal cluster defects were found in 12.3 % and 3.1 % of eyes on the interocular and monocular amplitude analysis mfVEP probability plots, respectively. As well, mfVEP latencies delays were found in 13.8 and 20 % of eyes on the interocular and monocular analysis probability plots, respectively. Interestingly, 19 % of patients with GO had ocular hypertension, and a strong correlation between intraocular pressure measured at upgaze and mfVEP latency was found. MfVEP amplitudes and visual acuity were significantly related to each other (P < 0.05), but not with the latencies delays. However, relationships between the interocular or monocular mfVEP amplitudes and latencies analysis and SAP indices or OCT data were not statistically significant. One-third of our patients with GO showed changes in the mfVEP, indicating significant subclinical optic nerve dysfunction. In this sense, the mfVEP may be a useful diagnostic tool in the clinic for early diagnosis and monitoring of optic nerve function abnormalities in patients with GO.
authors.affiliation: Department of Ophthalmology, University Hospital Príncipe de Asturias, University of Alcalá, Carretera Alcalá-Meco s/n, 28805, Alcalá de Henares, Madrid, Spain. cinta.perezrico@gmail.com
authors.forename: Consuelo
authors.initials: C
authors.lastname: Pérez-Rico
authors.forename: Natividad
authors.initials: N
authors.lastname: Rodríguez-González
authors.forename: Juan
authors.initials: J
authors.lastname: Arévalo-Serrano
authors.forename: Román
authors.initials: R
authors.lastname: Blanco
mesh_terms: D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D049970:Graves Ophthalmopathy / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000503:physiopathology; D009916:Orbital Diseases / Q000175:diagnosis* / Q000503:physiopathology; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology