title: Outcomes of laser peripheral iridotomy in angle closure subgroups according to anterior segment optical coherence tomography parameters.
abstract: OBJECTIVE
  To investigate the effect of laser peripheral iridotomy (LPI) in subgroups of angle closure eyes based on anterior segment optical coherence tomography (AS OCT)-derived parameters.
  
  
  METHODS
  Angle closure (primary angle closure [PAC] or PAC glaucoma [PACG]) eyes were imaged using AS OCT before and 2 weeks after LPI. A hierarchical cluster analysis was performed using AS OCT parameters obtained before LPI, such as anterior chamber depth (ACD), anterior chamber width (ACW), iris cross-sectional area (IA), angle opening distance and iris thickness at 750 μm from the scleral spur (AOD750, IT750), iris curvature (IC), lens vault (LV), and anterior chamber area (ACA) to subclassify angle closure eyes. After LPI, parameters were compared to evaluate whether the outcome of LPI differed among the subgroups determined by cluster analysis.
  
  
  RESULTS
  Cluster analysis generated two distinct clusters showing significantly different anatomical features. Cluster 1 (61 eyes) had lower ACD (P<0.001), higher LV (P=0.008), lower AOD750 (P<0.001), and lower ACW (P<0.001) than cluster 2 (27 eyes). The proportional change in AOD750 after LPI was significantly greater in cluster 1 than in cluster 2 (116.4±117.3% and 46.4±45.7%, respectively, P=0.007).
  
  
  CONCLUSIONS
  The outcomes of LPI differed between angle closure subgroups with different anatomical characteristics. Our results provide evidence that angle closure patients can be grouped according to different anatomical anterior segment features and that the pathogenic mechanism of angle closure may differ among subgroups, suggesting that the treatment and follow-up plan should be customized according to subgroup features.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Seungbong
authors.initials: S
authors.lastname: Han
authors.affiliation: Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Kyung Rim
authors.initials: KR
authors.lastname: Sung
authors.affiliation: Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Kyoung Sub
authors.initials: KS
authors.lastname: Lee
authors.affiliation: Department of Ophthalmology, University of Ulsan, College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Ji Wook
authors.initials: JW
authors.lastname: Hong
mesh_terms: D000869:Anterior Eye Segment / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D015812:Glaucoma, Angle-Closure / Q000473:pathology / Q000601:surgery*; D006068:Gonioscopy; D006801:Humans; D032801:Iridectomy / Q000379:methods*; D007498:Iris / Q000473:pathology / Q000601:surgery; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D041623:Tomography, Optical Coherence / Q000379:methods*; D016896:Treatment Outcome
keywords: AS OCT; angle closure; glaucoma; laser peripheral iridotomy; pupillary block