title: Retinal adaptation abnormalities in primary open-angle glaucoma.
abstract: OBJECTIVE
  Dynamic color and brightness adaptation are crucial for visual functioning. The effects of glaucoma on retinal ganglion cells (RGCs) could compromise these functions. We have previously used slow dynamic changes of light at moderate intensities to measure the speed and magnitude of subtractive adaptation in RGCs. We used the same procedure to test if RGC abnormalities cause slower and weaker adaptation for patients with glaucoma when compared to age-similar controls. We assessed adaptation deficits in specific classes of RGCs by testing along the three cardinal color axes that isolate konio, parvo, and magno RGCs.
  
  
  METHODS
  For one eye each of 10 primary open-angle glaucoma patients and their age-similar controls, we measured the speed and magnitude of adapting to 1/32 Hz color modulations along the three cardinal axes, at central fixation and 8° superior, inferior, nasal, and temporal to fixation.
  
  
  RESULTS
  In all 15 comparisons (5 locations × 3 color axes), average adaptation was slower and weaker for glaucoma patients than for controls. Adaptation developed slower at central targets than at 8° eccentricities for controls, but not for patients. Adaptation speed and magnitude differed between affected and control eyes even at retinal locations showing no visual field loss with clinical perimetry.
  
  
  CONCLUSIONS
  Neural adaptation is weaker in glaucoma patients for all three classes of RGCs. Since adaptation abnormalities are manifested even at retinal locations not exhibiting a visual field loss, this novel form of assessment may offer a functional insight into glaucoma and an early diagnosis tool.
authors.affiliation: Department of Biological & Visual Sciences and Graduate Center for Vision Research, State University of New York College of Optometry, New York, New York, United States.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Dul
authors.affiliation: Department of Biological & Visual Sciences and Graduate Center for Vision Research, State University of New York College of Optometry, New York, New York, United States.
authors.forename: Robert
authors.initials: R
authors.lastname: Ennis
authors.affiliation: Department of Biological & Visual Sciences and Graduate Center for Vision Research, State University of New York College of Optometry, New York, New York, United States.
authors.forename: Shira
authors.initials: S
authors.lastname: Radner
authors.affiliation: Department of Biological & Visual Sciences and Graduate Center for Vision Research, State University of New York College of Optometry, New York, New York, United States.
authors.forename: Barry
authors.initials: B
authors.lastname: Lee
authors.affiliation: Department of Biological & Visual Sciences and Graduate Center for Vision Research, State University of New York College of Optometry, New York, New York, United States.
authors.forename: Qasim
authors.initials: Q
authors.lastname: Zaidi
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D012160:Retina / Q000503:physiopathology*; D012165:Retinal Ganglion Cells / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*
keywords: adaptation; ganglion cells; glaucoma