title: Hemifield pattern electroretinogram in ocular hypertension: comparison with frequency doubling technology and optical coherence tomography to detect early optic neuropathy.
abstract: BACKGROUND
  To assess the sensitivity and specificity of hemifield pattern electroretinogram (HF-PERG) for detecting early retinal ganglion cell (RGC) damage in ocular hypertensive (OH) patients.
  
  
  METHODS
  Fifty-two OH patients (mean age 56±9.6 years) with an intraocular pressure (IOP) .21 mmHg were assessed. All subjects underwent HF-PERG, optical coherence tomography (OCT), and frequency doubling technology (FDT) visual field.
  
  
  RESULTS
  OH patients showed a significant increase of peak-time of the N95 (P=0.027) compared to controls. The amplitude of the N95 of the lower and upper HF-PERG showed significant differences (P=0.037 and P=0.023, respectively) between the two groups. A significant intraocular (P=0.006) and interocular (P=0.018) asymmetry of N95 amplitude was found. Receiver operating characteristic (ROC) curve analysis revealed a sensitivity of 93% for the N95 of the lower HF-PERG, whereas full-field pattern electroretinogram (PERG) N95 peak-time had a sensitivity of 88%. In OH patients, we found a thinning of OCT - retinal nerve fiber layer (RNFL), especially in the superior and inferior quadrant, although not statistically significant, and a significantly higher FDT pattern standard deviation (FDT-PSD; P=0.001). In the OCT-RNFL inferior quadrant, a sensitivity of 82% was recorded. Finally, the sensitivity of the FDT-PSD was 92%.
  
  
  CONCLUSIONS
  Our study shows that HF-PERG is a very sensitive test for detecting early damage of the RGC.
authors.affiliation: Department of Specialized, Diagnostic and Experimental Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Finzi
authors.affiliation: Department of Specialized, Diagnostic and Experimental Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Strobbe
authors.affiliation: Department of Specialized, Diagnostic and Experimental Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Tassi
authors.affiliation: Department of Specialized, Diagnostic and Experimental Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Fresina
authors.affiliation: Department of Specialized, Diagnostic and Experimental Medicine, Ophthalmology Service, University of Bologna, Bologna, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Cellini
keywords: frequency doubling technology; hemifield pattern electroretinogram; ocular hypertension; optical coherence tomography