[Visual evoked potentials in diagnosis and monitoring of optic neuropathy in the course of thyroid ophthalmopathy].
OBJECTIVE
To evaluate the usefulness of pattern visual evoked potentials (PVEP) in early diagnosis and monitoring of dysthyroid optic neuropathy (DON).


METHODS
We recorded PVEP (UTAS E--1000) in 74 patients with thyroid ophthalmopathy (TO) including 12 patients with clinically evident DON--group I, 13 patients with subclinical DON (prolongation of latency of P100 wave in PVEP)--group II, and 49 patients without clinical or electrophysiological signs of DON--group III. Thirty six healthy subjects served as controls. The latencies of P100 and N75 waves were examined. In 50 TO patients we recorded changes in PVEP before and after treatment.


RESULTS
The mean LP100 and LN75 were significantly longer in TO patients compared to control group. In groups I and II they were also significantly longer in comparison to group III. We observed prolongation of LP100 above the upper limit of normal values in all patients with clinically evident DON and in 13/62 (21%) cases without clinical signs of optic nerve dysfunction. The prolongation of LP100 was present in 16/21 (76.2%) eyes in group I and in 15/26 (57.7%) eyes in group II. Prolongation of LN75 was less frequent: group I--5/21 (23.8%), group II--2/26 (7.7%). After treatment in patients with clinically evident DON the latencies of both waves were significantly shorter in comparison to values obtained before therapy. In group II statistically significant differences were observed only in LP100. The percentage of eyes with prolonged latencies was significantly smaller after treatment (group I: LP100--3/23 (13.0%), LN75--1/23 (4.3%); group II: LP100--2/18 (11.1%), LN75--no prolongation was observed).


CONCLUSIONS
PVEP is an useful method in diagnosis and monitoring of dysthyroid optic neuropathy. It can reveal even asymptomatic optic nerve dysfunctions. Detection of subclinical neuropathy using PVEP enables early--thus more effective--treatment. The most important factor in PVEP evaluation is the latency of P100 wave, the latency of N75 wave is less useful.
Rutecka-Debniak
A
A
Katedry i Kliniki Okulistyki (W.S.) Pomorskiej AM w Szczecinie.
Lubiński
W
W
Krzystolik
Z
Z
D000293:Adolescent; D000328:Adult; D000368:Aged; D018450:Disease Progression; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D006111:Graves Disease / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009900:Optic Nerve / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology