title: Photopic Negative Response Obtained Using a Handheld Electroretinogram Device: Determining the Optimal Measure and Repeatability.
abstract: OBJECTIVE
  To determine the measure of the photopic negative response (PhNR) of the full-field electroretinogram (ERG) that exhibits the optimal level of test-retest repeatability, and examine its repeatability under different conditions using a handheld, nonmydriatic ERG system and self-adhering skin electrodes.
  
  
  METHODS
  Multiple ERG recordings (using 200 sweeps each) were performed in both eyes of 20 normal participants at two different sessions to compare its coefficient of repeatability (CoR; where 95% of the test-retest difference is expected to lie) between different PhNR measures and under different testing conditions (within and between examiners, and between sessions).
  
  
  RESULTS
  The ratio between the PhNR trough to b-wave peak and b-wave peak to a-wave trough amplitude (PhNR/B ratio) exhibited the lowest CoR relative to its effective dynamic range (30 ± 4%) when including three recordings. There were no significant changes in the PhNR/B ratio over seven measurements (4 right and 3 left eyes) at either session (P≥ 0.100), or significant difference in its CoR between different testing conditions (P= 0.314).
  
  
  CONCLUSIONS
  The PhNR/B ratio was the measure that minimized variability, and its measurements using a novel handheld ERG system with self-adhering skin electrodes and the protocols described in this study were comparable under different testing conditions and over multiple recordings.
  
  
  CONCLUSIONS
  The PhNR can be measured for clinical and research purposes using a simple-to-implement technique that is consistent within and between visits, and also between examiners.
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia.
authors.forename: Zhichao
authors.initials: Z
authors.lastname: Wu
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia.
authors.forename: Xavier
authors.initials: X
authors.lastname: Hadoux
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia.
authors.forename: Flora
authors.initials: F
authors.lastname: Hui
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia.
authors.forename: Marc G
authors.initials: MG
authors.lastname: Sarossy
authors.affiliation: Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia ; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Crowston
keywords: electroretinogram; ganglion cell function; glaucoma; photopic negative response