title: Evaluation of pattern ERG as a visual prognosticator in chiasmatic tumours.
abstract: BACKGROUND
  Tumours compressing the optic pathway may lead to irreversible loss of vision that can be detected by pattern electroretinogram owing to its relation to ganglion cell function. This study aims to assess whether pattern electroretinogram is a useful tool to predict visual outcome following decompressive surgery for sellar and parasellar tumours.
  
  
  METHODS
  Prospective, non-randomized study.
  
  
  METHODS
  Forty eyes of 20 patients with radiologically confirmed tumours in and around the sellar region.
  
  
  METHODS
  Patients were followed for 6 weeks following surgical intervention (transphenoidal or transfrontal approach).
  
  
  METHODS
  Best-corrected visual acuity, visual fields (Humphrey 30-2 standard automated perimetry) and pattern electroretinogram. The ratio N95/P50 (N2/P1) was calculated for each recording.
  
  
  RESULTS
  There was improvement in visual fields in 35.4% eyes with normal n2/p1 ratio (>1.1) as compared to 22.2% with abnormal ratio. Also, 9.6% eyes with normal ratio and 11.1% with an abnormal ratio deteriorated postoperatively. No association was found between pattern electroretinogram and visual fields preoperatively and postoperatively (P = 0.093).
  
  
  CONCLUSIONS
  Pattern electroretinogram may not be a useful prognostic indicator in the preoperative assessment of tumours causing chiasmal compression. An abnormal N2/P1 ratio is not necessarily associated with lesser or no clinical improvement following surgery as compared to an eye with a normal pattern electroretinogram.
authors.affiliation: Guru Nanak Eye Centre, Maulana Azad Medical College, New Delhi, India.
authors.forename: Jawahar L
authors.initials: JL
authors.lastname: Goyal
authors.forename: Lanalyn
authors.initials: L
authors.lastname: Thangkhiew
authors.forename: Usha
authors.initials: U
authors.lastname: Yadava
authors.forename: Ritu
authors.initials: R
authors.lastname: Arora
authors.forename: Parul
authors.initials: P
authors.lastname: Jain
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000473:pathology* / Q000601:surgery; D002648:Child; D019299:Decompression, Surgical; D004596:Electroretinography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009408:Nerve Compression Syndromes / Q000175:diagnosis* / Q000601:surgery; D009897:Optic Chiasm / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000601:surgery; D011379:Prognosis; D011446:Prospective Studies; D014786:Vision Disorders / Q000175:diagnosis*; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways
keywords: chiasmal compression; pattern electroretinogram; sellar tumour