title: Selective amplitude reduction of the PhNR after macular hole surgery: ganglion cell damage related to ICG-assisted ILM peeling and gas tamponade.
abstract: OBJECTIVE
  The photopic negative response (PhNR) is a negative component of the photopic electroretinogram (ERG) that is observed after the b-wave and is thought to originate mainly from the activity of ganglion cells and their axons. The purpose of this study was to determine whether there are subclinical functional changes in the inner retina after macular hole surgery, by recording the PhNR before and after surgery.
  
  
  METHODS
  In addition to the routine ophthalmic examinations, photopic ERGs were recorded in 16 eyes with an idiopathic macular hole, before and 3 months after surgery. Photopic ERGs were elicited by white Ganzfeld flashes on a rod-suppressing blue background. The amplitude of the PhNR and the a- and b-waves of the photopic ERGs before and after surgery were compared. PhNRs were also recorded in 14 eyes with epiretinal membrane, before and after surgery.
  
  
  RESULTS
  Macular holes were closed and visual acuities were improved without any serious complications in all eyes with a macular hole. The amplitude of the PhNR was significantly reduced after surgery (P < 0.05), whereas the amplitude of the photopic a- and b-waves were not significantly altered. For eyes with an epiretinal membrane, the mean amplitude of the PhNR was slightly decreased after the surgery, but the degree of reduction was only one half of that after macular hole surgery.
  
  
  CONCLUSIONS
  These results suggest that there are some functional impairments in the inner retina after macular hole surgery, even though the patients did not show any reduction on subjective visual tests. The PhNR can be a useful clinical test to assess the inner retinal function objectively, before and after vitreoretinal surgery.
authors.affiliation: Department of Ophthalmology, Nagoya University School of Medicine, Japan. ueno@med.nagoya-u.ac.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Ueno
authors.forename: Mineo
authors.initials: M
authors.lastname: Kondo
authors.forename: Chang-Hua
authors.initials: CH
authors.lastname: Piao
authors.forename: Kazuteru
authors.initials: K
authors.lastname: Ikenoya
authors.forename: Yozo
authors.initials: Y
authors.lastname: Miyake
authors.forename: Hiroko
authors.initials: H
authors.lastname: Terasaki
mesh_terms: D000221:Adaptation, Ocular; D000368:Aged; D001369:Axons / Q000502:physiology*; D001485:Basement Membrane / Q000601:surgery; D004396:Coloring Agents; D004596:Electroretinography; D019773:Epiretinal Membrane / Q000601:surgery; D005260:Female; D005466:Fluorocarbons / Q000008:administration & dosage*; D006801:Humans; D007208:Indocyanine Green; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012160:Retina / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012167:Retinal Perforations / Q000503:physiopathology* / Q000601:surgery*; D014792:Visual Acuity; D014821:Vitrectomy
chemical_list: D004396:Coloring Agents; D005466:Fluorocarbons; C042852:perflutren; D007208:Indocyanine Green