title: Laser peripheral iridotomy in primary angle-closure suspects: biometric and gonioscopic outcomes: the Liwan Eye Study.
abstract: OBJECTIVE
  To assess the immediate effect of laser peripheral iridotomy (LPI) and mechanisms of angle closure in a population-based study of primary angle closure (PAC) suspects.
  
  
  METHODS
  Prospective interventional study.
  
  
  METHODS
  People identified as PAC suspects aged 50 to 79 years from a population-based survey in Guangzhou, China.
  
  
  METHODS
  Laser peripheral iridotomy was performed in 1 randomly selected eye. Examinations were carried out before and 2 weeks after the intervention.
  
  
  METHODS
  Intraocular pressure (IOP), ultrasound biometry, optical pachymetry, and gonioscopy.
  
  
  RESULTS
  A total of 72 people with bilateral suspected PAC participated in the study. Mean IOP decreased by 3 mmHg (P<0.001), but axial anterior chamber depth did not change significantly (P = 0.784) after LPI. Median limbal anterior chamber depth increased from 15% to 25% of peripheral corneal thickness (P<0.001, Wilcoxon signed-rank test). Median iridotrabecular angle width increased from 0 degrees to 10 degrees in the superior quadrant and from 10 degrees to 30 degrees in the inferior quadrant (P<0.001). Nevertheless, 14 eyes (19.4%) still had 3 or more quadrants in which the posterior (usually pigmented) trabecular meshwork could not be seen after laser iridotomy.
  
  
  CONCLUSIONS
  This study confirms that LPI results in a significant increase in the angle width in Chinese people with narrow angles. However, one fifth of eyes had residual angle closure after LPI. Although this report confirms that iridotomy widens the anterior chamber angle in most PAC suspects, long-term prospective studies with a larger sample size are required to determine if the risks of PAC glaucoma and other related pathologic sequelae are reduced after prophylactic LPI and to investigate the risk-to-benefit ratio before recommending widespread use of prophylactic LPI in this population.
authors.affiliation: Institute of Ophthalmology, University College London, London, United Kingdom. mingguang_he@yahoo.com
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.forename: Jian
authors.initials: J
authors.lastname: Ge
authors.forename: Wenyong
authors.initials: W
authors.lastname: Huang
authors.forename: Chenjin
authors.initials: C
authors.lastname: Jin
authors.forename: Pak Sang
authors.initials: PS
authors.lastname: Lee
authors.forename: Peng T
authors.initials: PT
authors.lastname: Khaw
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Foster
mesh_terms: D000368:Aged; D044466:Asian People; D001699:Biometry; D015331:Cohort Studies; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis / Q000208:ethnology / Q000503:physiopathology / Q000601:surgery*; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D007498:Iris / Q000601:surgery*; D053685:Laser Therapy; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011446:Prospective Studies; D016896:Treatment Outcome