title: Hidden mechanisms beyond the pupillary block in acute angle closure: ultrasound biomicroscopic study.
abstract: BACKGROUND
  To evaluate the mechanisms of acute angle closure (AAC) other than the pupillary block using ultrasound biomicroscopy.
  
  
  METHODS
  Retrospective chart review.
  
  
  METHODS
  All patients who were diagnosed with AAC in Ramathibodi Hospital, Bangkok, Thailand, between June 2011 and February 2015 were enrolled.
  
  
  METHODS
  Seventy-two patients who were diagnosed with AAC underwent a detailed ocular examination. The diagnosed mechanism of AAC was confirmed by UBM and ocular biometry.
  
  
  METHODS
  Primary mechanism responsible for acute angle closure.
  
  
  RESULTS
  In 72 patients, the mean age was 62.33 ± 10.4 years, 18 (25%) patients were male and 54 (75%) patients were female. The primary mechanism of AAC was iridolenticular wrapping (crowded-angle (CR) plus anterior lens subluxation (LS)) in 49 eyes (68.1%), pupillary block (PB) in 17 (23.6%) eyes, and plateau iris (PL) in 6 (8.3%) eyes. Thirty (41.7%) out of 72 eyes without previous iridotomy before UBM examination were analyzed. The most common primary mechanism in this group was iridolenticular wrapping (20 eyes, 66.7%). There were seven (23.3%) eyes that had a pupillary block, and only three (10.0%) eyes had plateau iris syndrome as the primary mechanism of AAC. There was a single mechanism in 14 (46.7%) eyes, and there were combined mechanisms in 16 (53.3%) eyes.
  
  
  CONCLUSIONS
  The most common mechanism contributing to AAC development in this Thai population was iridolenticular wrapping. From this study, we suggest that iridolenticular wrapping was the most common hidden mechanism beyond pupillary block among Thai patients.
authors: Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Yanin
authors: Y
authors: Suwan
authors: Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Sunpong
authors: S
authors: Jiamsawad
authors: Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Wasu
authors: W
authors: Supakontanasan
authors: Department of Ophthalmology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
authors: Chaiwat
authors: C
authors: Teekhasaenee
mesh_terms: D000208:Acute Disease; D003937:Diagnosis, Differential; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D007499:Iris Diseases / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D033401:Microscopy, Acoustic / Q000379:methods*; D008875:Middle Aged; D011681:Pupil Disorders / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D012189:Retrospective Studies
keywords: acute angle closure; crowded-angle; plateau iris; ultrasound biomicroscopy