title: Association between light-to-dark changes in angle width and iris parameters in light, dark and changes from light-to-dark conditions.
abstract: OBJECTIVE
  To evaluate the association between light-to-dark changes in angle width parameters and iris parameters in light, dark and changes from light-to-dark conditions.
  
  
  METHODS
  In this prospective, cross-sectional study, anterior segment optical coherence tomography images, obtained under light and dark conditions, were analysed to determine angle opening distance measured at 500 μm from the scleral spur (AOD500), trabecular-iris space area at 500 μm from the scleral spur (TISA500), iris thickness measured at 750 μm from the scleral spur (IT750), iris thickness measured at 2000 μm from the scleral spur (IT2000), iris area (IArea) and pupil diameter (PD). Multivariable linear mixed-effect regression models were used to evaluate the association between light-to-dark changes in angle width parameters (AOD500, TISA500) and iris parameters (IT750, IT2000, IArea, PD) in light, dark and changes from light-to-dark conditions.
  
  
  RESULTS
  534 eyes from 314 non-glaucomatous subjects were analysed. IT750, IT2000, IArea and PD in light conditions were significantly associated with light-to-dark changes in AOD500 (p<0.05). IT750, IT2000 and IArea in light conditions were significantly associated with light-to-dark changes in TISA500 (p<0.05). IT750 in dark conditions was significantly associated with light-to-dark changes in AOD500 and TISA500 (p<0.05). Light-to-dark changes in IT2000, IArea and PD were significantly associated with light-to-dark changes in AOD500 (p<0.05). Light-to-dark changes in IArea were significantly associated with light-to-dark changes in TISA500 (p<0.05).
  
  
  CONCLUSIONS
  Evaluation of iris parameters in light, dark and changes from light-to-dark conditions demonstrated that IT750, IT2000, IArea and PD in light conditions are significant predictors of light-to-dark changes in angle width.
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, California, USA Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA.
authors.forename: Roland Y
authors.initials: RY
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, California, USA.
authors.forename: Shuai-Chun
authors.initials: SC
authors.lastname: Lin
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, California, USA Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
authors.forename: Rebecca I
authors.initials: RI
authors.lastname: Chen
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, California, USA Department of Ophthalmology, Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil.
authors.forename: Diego T
authors.initials: DT
authors.lastname: Barbosa
authors.affiliation: Department of Ophthalmology, University of California, San Francisco, California, USA.
authors.forename: Shan C
authors.initials: SC
authors.lastname: Lin
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology*; D000368:Aged; D000869:Anterior Eye Segment / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D003623:Dark Adaptation / Q000502:physiology; D005260:Female; D005901:Glaucoma / Q000175:diagnosis / Q000503:physiopathology*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D007498:Iris / Q000000981:diagnostic imaging* / Q000528:radiation effects; D008027:Light; D008297:Male; D011446:Prospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods
keywords: Glaucoma; Imaging; Iris