title: Quantitative analysis of iris changes following mydriasis in subjects with different mechanisms of angle closure.
abstract: OBJECTIVE
  We estimate and compare change in iris cross-sectional area (IA) after physiologic and pharmacologic mydriasis in subjects with different dominant mechanisms for primary angle closure.
  
  
  METHODS
  Anterior segment optical coherence tomography (AS-OCT) measurements in light, dark, and following pharmacologic dilation were obtained on primary angle closure suspects (PACS), primary angle closure (PAC), and primary angle closure glaucoma (PACG) examined during the 5-year follow-up of the Handan Eye Study. Subjects were categorized into three subgroups according to their dominant angle closure (AC) mechanisms as determined by AS-OCT: pupillary block (PB), plateau iris configuration (PIC), and thick peripheral iris roll (TPIR). The IA and other biometric parameters measured using the Zhongshan Angle Assessment Program in the right eyes of all subjects were analyzed.
  
  
  RESULTS
  A total of 364 right eyes of subjects with PACS (333), and PAC/PACG (31) was included in the analysis. Significant differences in the change of IAs (P = 0.030), IA loss per mm pupil diameter (PD) increase (P = 0.001) in light versus pharmacologic dilation, and IA loss per mm PD increase (P = 0.011) from dark versus pharmacologic dilation were observed among the three groups. The smallest decrease occurred in the PB group.
  
  
  CONCLUSIONS
  There are significant differences in IA and IA loss per mm of pupil change following physiologic or pharmacologic mydriasis in Chinese subjects with dissimilar dominant mechanisms for AC. Dynamic iris change may have a more important role in angle closure where PB is the dominant mechanism.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Lab, Beijing, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Nanjing Aier Eye Hospital, Nanjing, China.
authors.forename: Si Zhen
authors.initials: SZ
authors.lastname: Li
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Lab, Beijing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Ming Guang
authors.initials: MG
authors.lastname: He
authors.affiliation: Queensland Eye Institute, Brisbane, Australia University of Queensland, Brisbane, Australia.
authors.forename: Ravi
authors.initials: R
authors.lastname: Thomas
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Lab, Beijing, China Beijing Institute of Ophthalmology, Beijing, China.
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D003623:Dark Adaptation; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000503:physiopathology*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D007498:Iris / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009184:Mydriatics / Q000008:administration & dosage*; D011680:Pupil / Q000187:drug effects* / Q000528:radiation effects*; D041623:Tomography, Optical Coherence; D014331:Tropicamide / Q000008:administration & dosage
chemical_list: D009184:Mydriatics; D014331:Tropicamide
keywords: angle closure mechanism; anterior segment optical coherence tomography; iris cross-sectional area; primary angle closure disease