title: Dynamic Iris Changes as a Risk Factor in Primary Angle Closure Disease.
abstract: OBJECTIVE
  We studied the association between dynamic iris changes and the spectrum of primary angle closure disease (PACD), using the anterior segment optical coherence tomography (ASOCT).
  
  
  METHODS
  Eligible primary angle closure (PAC), primary angle closure glaucoma (PACG), age, and sex comparable primary angle closure suspects (PACS) and normal subjects from the 5-year follow-up of the Handan Eye Study underwent ASOCT testing in dark and light conditions. The right eye of each subject was analyzed and biometric parameters including iris cross-sectional area (IA), lens vault (LV), pupil diameter (PD), and centroid-to-centroid distance (CCD) were calculated using the Zhongshan Angle Assessment Program.
  
  
  RESULTS
  Totals of 31 PACS, 31 PAC/PACG, and 31 normal eyes were eligible for analysis. Loss of IA per mm PD increase in the dark compared to light was 0.18 mm in PACS, 0.13 mm in PAC/PACG, and 0.24 mm in normal (P = 0.015 between groups) groups. Diagnoses of normal (P = 0.001) and a smaller PD in light (P = 0.003) were statistically significant determinants of a larger IA loss per mm PD increase in the dark compared to light. Logistic regression analysis showed that LV (P = 0.002) and IA loss per mm PD increase (P = 0.017) were risk factors for an occludable angle.
  
  
  CONCLUSIONS
  Significant differences in iris behavior in the dark compared to light in PACS, PACD, and normal eyes add to the evidence that dynamic iris change has a role in the pathogenesis of PAC in a rural Chinese population.
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 5University 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 6Beijing Institute of Ophthalmology, Beijing, China.
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
mesh_terms: D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003623:Dark Adaptation / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D007429:Intraocular Pressure; D007498:Iris / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012424:Rural Population; D013997:Time Factors; D041623:Tomography, Optical Coherence