title: The Photopic Negative Response in Idiopathic Intracranial Hypertension.
abstract: OBJECTIVE
  To evaluate the photopic negative response (PhNR) as an index of retinal ganglion cell (RGC) function in idiopathic intracranial hypertension (IIH).
  
  
  METHODS
  Amplitude and implicit time of the PhNR, as elicited by full-field, brief-luminance flashes, was measured in IIH (n = 10) and visually normal control (n = 15) subjects. Visual function was assessed in IIH subjects using standard automated perimetry mean deviation (SAP-MD) scores. Optic nerve structure was evaluated using the Frisén papilledema grading scale (FPG). Macula ganglion cell complex volume (GCCV) was extracted from optical coherence tomography images to assess RGC loss.
  
  
  RESULTS
  Median PhNR amplitude was significantly lower in IIH subjects compared with control subjects (P = 0.015, Mann-Whitney Rank Sum [MW]), but implicit time was similar (P = 0.54, MW). In IIH subjects, PhNR amplitude and SAP-MD were correlated (Pearson's r = 0.78, P = 0.008). Ganglion cell complex volume was correlated with both SAP-MD (r = 0.72, P = 0.019) and PhNR amplitude (r = 0.77, P = 0.009). Multivariate linear regression models demonstrated that the correlation between GCCV and PhNR amplitude was improved by accounting for FPG in the model (r = 0.94, P < 0.0001), but the correlation between GCCV and SAP-MD was not (r = 0.74, P = 0.009).
  
  
  CONCLUSIONS
  Photopic negative response amplitude, which can be decreased in IIH subjects, correlates well with a clinical measure of visual function (SAP-MD). In multivariate models, it correlated with both an imaging measure of chronic ganglion cell injury (GCCV) and a clinical measure of acute optic nerve head pathology (FPG). Further studies are needed to determine the clinical utility of PhNR as a marker for diagnosis and monitoring of IIH.
authors.affiliation: Department of Ophthalmology and Visual Sciences University of Illinois at Chicago, Chicago, Illinois, United States 2Department of Neurology and Rehabilitation, University of Illinois at Chicago, Chicago, Illinois, United States.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Moss
authors.affiliation: Department of Ophthalmology and Visual Sciences University of Illinois at Chicago, Chicago, Illinois, United States.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Park
authors.affiliation: Department of Ophthalmology and Visual Sciences University of Illinois at Chicago, Chicago, Illinois, United States.
authors.forename: J Jason
authors.initials: JJ
authors.lastname: McAnany
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D011446:Prospective Studies; D011559:Pseudotumor Cerebri / Q000503:physiopathology*; D055815:Young Adult