B. Sadowski et al., ELECTROPHYSIOLOGICAL AND PSYCHOPHYSICAL EXAMINATION IN PATIENTS WITH OPTIC-NERVE COMPRESSION, Neuro-ophthalmology, 15(5), 1995, pp. 223-231
Compression of the optic nerve causes a descending degeneration of opt
ic nerve fibers. Additionally to the clinical symptoms (loss of visual
acuity, scotomas), electrophysiological methods can be used to evalua
te the function of the optic nerve (VEP) and the retinal ganglion cell
layer (pattern ERG, PERG). In order to investigate the prognostic sig
nificance of electrophysiological methods for postoperative recovery o
f visual function, II patients (22 eyes) suffering from compression of
the optic nerve or chiasm due to pituitary tumors or meningiomas were
investigated prior to and after surgical decompression. Visual acuity
and perimetry were compared to preoperatively performed transient pat
tern VEP and transient PERG (N-(95) amplitude). Prior to surgery, the
patients suffered from impairment of visual acuity and scotomas. After
surgical decompression, visual acuity improved in seven eyes, remaine
d unchanged in II eyes and deteriorated in four eyes. Visual field def
ects improved in I3 eyes, one visual held deteriorated. In all patient
s preoperative VEP examination revealed pathological findings (half an
d Ganzfeld). Latency of half field VEPs was prolonged in five eyes in
which the corresponding visual fields were normal. The N-95 of the PER
G was also pathological in three eyes, which postoperatively did not r
eveal any improvement in visual fields. The results demonstrate that V
EP latency can be more sensitive than the PERG in the diagnosis of com
pression with subsequent descending degeneration of the optic nerve. P
athological latencies when stimulating with half field VEPs can indica
te a first subclinical damage of the optic nerve prior to psychophysic
al and morphological findings. Pathological PERGs prior to decompressi
on seem to indicate a poor prognosis concerning the improvement of psy
chophysical function after surgery.