title: Luminance-modulated adaptation of global flash mfERG: fellow eye losses in asymmetric glaucoma.
abstract: OBJECTIVE
  To use the global flash multifocal electroretinogram (mfERG) in patients with asymmetric glaucoma to determine whether retinal function is affected in fellow eyes that have no glaucomatous visual field defects.
  
  
  METHODS
  Forty normal subjects and 12 patients with asymmetric glaucoma were recruited for visual field and mfERG measurement. The mfERG was assessed by using a global-flash stimulation paradigm with four video frames: 103 scaled hexagonal elements followed by a dark frame, a global-flash frame, and a dark frame. The localized luminance difference was set at 96%, 65%, 49%, and 29% display contrast during the four different test conditions, respectively. The first-order kernel response was measured, and the "adaptive index" which has been used previously was calculated.
  
  
  RESULTS
  In fellow eyes with normal visual fields, the amplitude of the induced component (IC) was significantly reduced, and the adaptive index was reduced by a factor of almost 10 (P < 0.0001), as it was in the glaucomatous eyes. Although the adaptive index in the better (fellow) eye of the patients with glaucoma was slightly higher than in the eyes with diagnosed glaucoma, these differences were not statistically significant.
  
  
  CONCLUSIONS
  The significant reduction of the adaptive index in the better eyes in subjects with asymmetric glaucoma shows that the fast adaptive mechanism(s) were reduced in these eyes. This implies that eyes that have functionally normal visual acuity and visual fields have abnormal fast-adaptive mechanisms.
authors.affiliation: Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China.
authors.forename: Patrick H W
authors.initials: PH
authors.lastname: Chu
authors.forename: Henry H L
authors.initials: HH
authors.lastname: Chan
authors.forename: Brian
authors.initials: B
authors.lastname: Brown
mesh_terms: D000221:Adaptation, Ocular; D000328:Adult; D004596:Electroretinography; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D008875:Middle Aged; D010775:Photic Stimulation; D012160:Retina / Q000503:physiopathology*; D014786:Vision Disorders / Q000503:physiopathology*; D014794:Visual Fields / Q000502:physiology*