title: The post-illumination pupil response is reduced in glaucoma patients.
abstract: OBJECTIVE
  The post-illumination pupil response (PIPR), which is driven by the intrinsic response of melanopsin-containing, intrinsically photosensitive retinal ganglion cells, has previously been characterized in healthy eyes. The present study examined whether the PIPR is affected in patients with glaucoma compared with healthy subjects.
  
  
  METHODS
  Sixteen glaucoma patients (mean age, 63.7 years) were tested by presenting a 60°, 10-second light stimulus (13 log quanta/cm(2)/s retinal irradiance) of either 470 nm (blue) or 623 nm (red) to one eye after dilation. The consensual pupil response of the fellow undilated eye was recorded by infrared pupillometry for 50 seconds after light offset. These pupillary responses were compared with those of 19 age-matched controls (mean age, 59 years).
  
  
  RESULTS
  The glaucoma patients displayed a net PIPR (blue PIPR minus red PIPR) that was significantly (t-test, P < 0.001) smaller (0.6 mm, SEM 0.12; P < 0.05) than in age-matched controls (1.3 mm, SEM 0.16; P < 0.001). For the patient population, the magnitude of the net PIPR was inversely correlated with the measured visual field loss (mean deviation) of the tested eye.
  
  
  CONCLUSIONS
  This study demonstrates that there is a significant decrease in the ipRGC-mediated PIPR in glaucomatous patients when compared to age-matched controls. As the severity of the glaucomatous neuropathy increases, there is a correlated decrease in the PIPR. Therefore, this test has the potential for use as a clinical tool in evaluating patients with glaucoma.
authors.affiliation: Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, Alabama 35294-0010, USA.
authors.forename: Laxmikanth
authors.initials: L
authors.lastname: Kankipati
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Girkin
authors.forename: Paul D
authors.initials: PD
authors.lastname: Gamlin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008027:Light; D008297:Male; D008875:Middle Aged; D009901:Optic Nerve Diseases / Q000503:physiopathology; D011680:Pupil / Q000528:radiation effects*; D012025:Reflex, Pupillary / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D014786:Vision Disorders / Q000503:physiopathology*; D014794:Visual Fields / Q000502:physiology*