title: Relationship between intraocular pressure and angle configuration: an anterior segment OCT study.
abstract: OBJECTIVE
  To assess the relationship between intraocular pressure (IOP) and anterior chamber angle (ACA) configuration as assessed by gonioscopy and anterior segment optical coherence tomography (AS-OCT).
  
  
  METHODS
  A total of 2045 subjects aged 50 years and older, were recruited from a community clinic and underwent AS-OCT, Goldmann applanation tonometry, and gonioscopy. A quadrant was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen. A closed quadrant on AS-OCT was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure AS-OCT parameters on AS-OCT scans, including anterior chamber depth, area, and volume; iris thickness (IT) and curvature; lens vault; angle opening distance; and trabecular-iris space area. IOP values were adjusted for age, sex, diabetes and hypertension status, body mass index, central corneal thickness, and presence of peripheral anterior synechiae.
  
  
  RESULTS
  Mean age of study subjects was 63.2 ± 8.0 years, 52.6% were female, and 89.4% were Chinese. Mean IOP was 14.8 ± 2.4 mm Hg (range 826). IOP (mean ± SE) increased with number of quadrants with gonioscopic angle closure (none: 14.6 ± 0.2; one: 14.7 ± 0.3; two: 15.0 ± 0.3; three: 15.0 ± 0.3; four: 15.6 ± 0.3 mm Hg; P < 0.001), and on AS-OCT (none: 14.7 ± 0.2; one: 15.0 ± 0.2; two: 14.8 ± 0.2; three: 15.1 ± 0.3; four: 16.0 ± 0.3 mm Hg; P < 0.001). IOP also increased in association with most of the ACA quantitative parameters measured on AS-OCT images, except for IT and lens vault.
  
  
  CONCLUSIONS
  There was an association between the extent of angle closure, as assessed on AS-OCT and gonioscopy, with increasing IOP.
authors.affiliation: Singapore Eye Research Institute and Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore.
authors.forename: Rachel S
authors.initials: RS
authors.lastname: Chong
authors.forename: Lisandro M
authors.initials: LM
authors.lastname: Sakata
authors.forename: Arun K
authors.initials: AK
authors.lastname: Narayanaswamy
authors.forename: Sue-Wei
authors.initials: SW
authors.lastname: Ho
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
authors.forename: Mani
authors.initials: M
authors.lastname: Baskaran
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Shamira A
authors.initials: SA
authors.lastname: Perera
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
mesh_terms: D000869:Anterior Eye Segment / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D007498:Iris / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012846:Singapore; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D014129:Trabecular Meshwork / Q000473:pathology