title: Photopic negative response of focal electoretinograms in glaucomatous eyes.
abstract: OBJECTIVE
  To determine the clinical importance of the photopic negative response (PhNR) of the focal electoretinogram (fERG) for diagnosing glaucoma.
  
  
  METHODS
  Fifty-nine eyes of 38 patients with open-angle glaucoma (OAG), 12 glaucoma suspects, and 32 eyes of 32 normal controls were studied. The fERGs were elicited by a 15 degrees stimulus spot on the macula region, the supero-temporal, and infero-temporal regions of the macula. The mean of the visual sensitivity was measured by standard automated perimetry (SAP). The optimal cutoff amplitudes of the focal PhNR and ratios of the focal PhNR/b-wave amplitudes that discriminated glaucomatous eyes from normal eyes were obtained from the receiver operating characteristic curves.
  
  
  RESULTS
  The amplitudes of the PhNR were significantly smaller in patients with OAG than in normal controls (P < 0.00001). A curvilinear relationship was found between the mean sensitivity (dB, on log scale) and the PhNR amplitude, and between the mean sensitivity and the PhNR/b-wave amplitude ratio. After converting the mean sensitivity from a logarithmic to a linear scale, the amplitude of the PhNR and PhNR/b-wave ratio were linearly correlated with the SAP-determined visual sensitivity in all retinal areas (r = .428-0.544, P < 0.0001). When the optimal cutoff values were used, the sensitivity and specificity of the PhNR/b-wave amplitude ratio were 98.3% and 90.1%, respectively.
  
  
  CONCLUSIONS
  The reduction of the focal PhNR amplitude was associated with a local decrease in the retinal sensitivity in OAG. The high sensitivity and specificity suggest that the focal PhNR can be used to detect functional loss in OAG.
authors.affiliation: Department of Ophthalmology, Iwate Medical University School of Medicine, Iwate, Japan. smachida@iwate-med.ac.jp
authors.forename: Shigeki
authors.initials: S
authors.lastname: Machida
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Toba
authors.forename: Aki
authors.initials: A
authors.lastname: Ohtaki
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Gotoh
authors.forename: Muneyoshi
authors.initials: M
authors.lastname: Kaneko
authors.forename: Daijiro
authors.initials: D
authors.lastname: Kurosaka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001369:Axons / Q000502:physiology*; D004596:Electroretinography; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis / Q000503:physiopathology; D009898:Optic Disk / Q000473:pathology; D009901:Optic Nerve Diseases / Q000175:diagnosis / Q000503:physiopathology*; D012160:Retina / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012680:Sensitivity and Specificity; D014794:Visual Fields