Functional Loss of the Inner Retina in Childhood Optic Gliomas Detected by Photopic Negative Response

• Published in: Investigative ophthalmology & visual science 2015-04, Vol.56 (4), p.2469-2474
• Main Authors: Abed, Edoardo, Piccardi, Marco, Rizzo, Daniela, Chiaretti, Antonio, Ambrosio, Lucia, Petroni, Sergio, Parrilla, Rosa, Dickmann, Anna, Riccardi, Riccardo, Falsini, Benedetto
• Format: Article
• Language: English
• Subjects: Adaptation, Ocular - physiology; Adolescent; Child; Child, Preschool; Color Vision - physiology; Electroretinography; Female; Humans; Male; Optic Nerve Glioma - diagnosis; Optic Nerve Glioma - physiopathology; Photic Stimulation - methods; Retinal Ganglion Cells - physiology; Tomography, Optical Coherence; Visual Acuity; Visual Fields
• ISSN: 1552-5783; 1552-5783
• DOI: 10.1167/iovs.14-16235

To determine whether the Ganzfeld ERG photopic negative response (PhNR), an assay of inner retinal activity, is altered in childhood optic glioma (OPG). Seventeen pediatric patients with a diagnosis of OPG, established on neuro-ophthalmologic and brain/orbit magnetic resonance imaging (MRI) criteria, were enrolled. The examination protocol included determination of visual acuity (VA), fundus examination, retinal nerve fiber layer (RNFL) measurement with spectral-domain optical coherence tomography (SD-OCT) and photopic ERG. Fifteen normal children served as control group. Ten of the 17 OPG patients were retested 1 to 3 months after the first examination. Photopic ERGs were recorded after 10 minutes of light adaptation in response to a Ganzfeld flash presented on a steady light-adapting background. Amplitude and peak-time of b-wave and PhNR were measured. Compared with normal values, PhNR amplitude was significantly reduced (P < 0.0001) in the OPG group. Peak-time of PhNR as well as b-wave amplitude and peak-time were similar in both patients and controls. Losses of PhNR were found in patients with involvement of either anterior or retro-chiasmatic optic pathways. Linear regression analysis showed significant positive correlation between RNFL thickness and PhNR amplitude (r2 = 0.34, P = 0.008). Mean percentage test-retest difference for PhNR amplitude and peak-time was 12% and 6%, respectively. These findings indicate that flash ERG PhNR can detect a loss of inner retinal function in childhood OPGs supporting the use of this technique, as an adjunct to standard psychophysical and electrophysiological tests, to monitor visual function in OPG.