Retrograde Optic Nerve Degeneration in Pituitary Adenoma: A Study with RE-PERG.

Abstract

RE-PERG is altered in presence of primary neuronal degeneration of retinal ganglion cells, both in glaucoma and other diseases. A previous study showed that in a model of retrograde degeneration (vascular dementia) RE-PERG was normal. In this study, we enrolled patients with pituitary adenoma (PA) to evaluate RE-PERG findings in another model of retrograde degeneration compared with healthy controls (HC). Based on the outcome of the present and our previous studies with RE-PERG, and reviewing the literature, we discuss the physiopathology of glaucoma. Twelve PA patients and 14 age-matched HC were recruited. All participants performed visual field (VF) test, retinal nerve fiber layer (RNFL) and ganglion cells complex (GCC) thickness measurement by means of optical coherence tomography (OCT), visual evoked potentials (VEPs) and RE-PERG, a non-invasive, fast steady-state pattern electroretinogram (SS-PERG) sampled in five consecutive blocks of 130 events. VEPs amplitude was significantly lower in PA with respect to HC (6.8±0.6 vs 7.4±0.6 µV; p=0.045). VEPs latency was higher in PA (123.2±5.8 vs 103.6±4.1 msec; p<0.01). As for VF, mean defect (MD) and pattern standard deviation (PSD) were higher in PA (-6.6±2.6 vs -0.01±1.02 dB; p<0.01 and 8.5±3.1 vs 1.5±0.3; p<0.01, respectively). RNFL thickness was lower in PA (88±8.1 vs 97±9.3 µ; p=0.01). There was no statistically significant difference between PA and HC for RE-PERG. There was a significant correlation among MD, PSD, VEPs amplitude, PERG amplitude and RNFL thickness in the PA group, whereas no correlation was found with SDPh, which remains as normal as in the HC group. Our findings confirm that RE-PERG is not altered in retrograde degeneration. Based on the outcome of the present and our previous studies about RE-PERG and glaucoma, we assume that in glaucoma a double mechanism of retinal ganglion cells degeneration, both retrograde and primary, can coexist.