title: Ultrasound biomicroscopy in the subtypes of primary angle closure glaucoma.
abstract: OBJECTIVE
  To evaluate the anterior segment parameters in the subtypes of primary angle closure glaucoma (PACG) using ultrasound biomicroscopy.
  
  
  METHODS
  Five groups, each comprising 30 consecutive patients, diagnosed to have subacute PACG, acute PACG, chronic PACG, primary open angle glaucoma (POAG), and healthy controls were included in the present study. All patients underwent slit-lamp biomicroscopy, direct ophthalmoscopy, 90D fundus examination, gonioscopy, applanation tonometry, visual field testing, A-scan biometry, and ultrasound biomicroscopy (UBM). The anterior segment parameters recorded included: trabecular-iris angle, angle opening distance, trabecular ciliary process distance, and the iris thickness among other parameters.
  
  
  RESULTS
  On ultrasound biomicroscopy the trabecular iris angle of control and POAG groups was more than all the subtypes of PACG (P < 0.001). The trabecular iris angle of subacute PACG (P < 0.001) and chronic PACG (P = 0.003) was more than acute PACG. Angle opening distance of controls and POAG group was significantly more than acute PACG and chronic PACG (P < 0.001). The trabecular ciliary process distance of POAG group and controls was more than subacute PACG, acute PACG, and chronic PACG. The trabecular ciliary process distance of subacute PACG (P < 0.001) and chronic PACG (P < 0.001) was more than acute PACG. Eyes with acute PACG had the least iris thickness at the three different positions tested. There was a positive correlation between the anterior chamber angle (trabecular iris angle) and the following parameters: trabecular ciliary process distance, angle opening distance, anterior chamber depth, and the axial length (r = 0.57).
  
  
  CONCLUSIONS
  Eyes with primary angle closure glaucoma have a thinner iris with a shorter trabecular iris angle, angle opening distance, and trabecular ciliary process distance. The eyes with acute primary angle closure glaucoma have the narrowest angle recess.
authors.affiliation: Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India. rjsihota@hotmail.com
authors.forename: Ramanjit
authors.initials: R
authors.lastname: Sihota
authors.forename: Tanuj
authors.initials: T
authors.lastname: Dada
authors.forename: Rajkumar
authors.initials: R
authors.lastname: Gupta
authors.forename: P
authors.initials: P
authors.lastname: Lakshminarayan
authors.forename: Ravindra M
authors.initials: RM
authors.lastname: Pandey
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000869:Anterior Eye Segment / Q000000981:diagnostic imaging*; D002908:Chronic Disease; D002924:Ciliary Body / Q000000981:diagnostic imaging*; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000145:classification / Q000000981:diagnostic imaging*; D005902:Glaucoma, Open-Angle / Q000000981:diagnostic imaging; D006801:Humans; D007429:Intraocular Pressure; D007498:Iris / Q000000981:diagnostic imaging*; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D014065:Tonometry, Ocular; D014794:Visual Fields