title: A positive association between intrinsically photosensitive retinal ganglion cells and retinal nerve fiber layer thinning in glaucoma.
abstract: OBJECTIVE
  To assess the integrity of intrinsically photosensitive retinal ganglion cells (ipRGCs) using the pupillary light reflex in glaucoma patients.
  
  
  METHODS
  A cross-sectional study was conducted, including 76 eyes from 38 patients with primary open-angle glaucoma and 36 eyes from 18 control subjects. The patients were tested in the dark with light stimuli using the Ganzfeld system, and the pupil diameter was measured with the assistance of an eye tracker consisting of two infrared cameras fit to an eyeglass frame. To preferentially stimulate ipRGCs, we used a 1-second 470-nm flash with a luminance of 250 cd/m(2). To stimulate different retinal photoreceptors (cones and rods), we used a 1-second 630-nm flash with a luminance of 250 cd/m(2). Standard automated perimetry (SAP), matrix frequency-doubling technology (FDT), and high-definition optical coherence tomography (Cirrus HD-OCT) were also performed. The correlation between the ipRGC-mediated sustained response following the pupillary light reflex and the structural and functional changes in glaucoma patients was analyzed using generalized estimating equation.
  
  
  RESULTS
  An association was observed between the average retinal nerve fiber layer (RNFL) thickness, as measured by Cirrus HD-OCT, and the sustained pupillary response to the blue flash (P = 0.024). The severity of glaucoma, based on the mean deviation of SAP (Hodapp-Anderson-Parrish system), was also associated with the sustained response to the blue flash (P = 0.006).
  
  
  CONCLUSIONS
  This study showed a correlation between the mean RNFL thickness and the pupillary light response. A decrease in the number of ipRGCs is potentially related to the reduced RNFL thickness.
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Carolina P B
authors.initials: CP
authors.lastname: Gracitelli
authors.affiliation: Psychology Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Gloria L
authors.initials: GL
authors.lastname: Duque-Chica
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil Psychology Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Ana Laura
authors.initials: AL
authors.lastname: Moura
authors.affiliation: Psychology Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Balazs V
authors.initials: BV
authors.lastname: Nagy
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Geraldine R
authors.initials: GR
authors.lastname: de Melo
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Marina
authors.initials: M
authors.lastname: Roizenblatt
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Paula D
authors.initials: PD
authors.lastname: Borba
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Sérgio H
authors.initials: SH
authors.lastname: Teixeira
authors.affiliation: Psychology Institute, University of São Paulo, São Paulo, Brazil.
authors.forename: Dora F
authors.initials: DF
authors.lastname: Ventura
authors.affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil.
authors.forename: Augusto
authors.initials: A
authors.lastname: Paranhos
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods; D011446:Prospective Studies; D011680:Pupil / Q000528:radiation effects*; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology
keywords: glaucoma; intrinsically photosensitive retinal ganglion cells; non–image-forming visual functions; pupil light reflex; retinal ganglion cells