title: Does an iridotomy provide protection against narrowing of the anterior chamber angle during Valsalva maneuvre in eyes with primary angle closure.
abstract: OBJECTIVE
  To evaluate changes at the anterior chamber angle during Valsalva manoeuver, in eyes having primary angle closure (PAC) and a patent laser peripheral iridotomy.
  
  
  METHODS
  Twenty-three eyes of 23 consecutive patients underwent a recording of applanation tonometry, measurement of the anterior chamber angle recess, angle opening distance, iris thickness, anterior chamber depth, and pupil size on ultrasound biomicroscopy before and during the Valsalva maneuver. The Valsalva manoeuver was standardized to a pressure of 40 mmHg for 15 s, using a manometer.
  
  
  RESULTS
  The mean baseline intraocular pressure changed from 18.86+3.79 to 26.73+4.73 mmHg during Valsalva, (P<0.0001). The anterior chamber angle recess narrowed from 16.62+6.24 to 6.5+4.02 degrees (P<0.0001). There was a significant increase in the thickness of the ciliary body from 0.92+0.25 to 1.17+0.31 mm (P=0.0006) and in the iris thickness from 0.47+0.17 to 0.57+0.11 mm (P=0.007). A significant increase in pupillary diameter (P=0.008) and a decrease in the angle opening distance (P<0.0001) also occurred during Valsalva, whereas there was no significant change in the anterior chamber depth (P=0.056). The angle recess during Valsalva had a positive correlation with the baseline anterior chamber angle (r=0.41, P=0.05) and a negative correlation with the ciliary body thickness (r=-0.52, P=0.046).
  
  
  CONCLUSIONS
  The induction of Valsalva maneuver in day-to-day activities can lead to significant anterior segment angle shallowing and can lead to progression from the PAC stage to primary angle closure glaucoma in such predisposed eyes. The presence of a patent laser iridotomy may not prevent irido trabecular apposition during the Valsalva maneuver.
authors.affiliation: Dr Rajendra Prasad Center for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: R
authors.initials: R
authors.lastname: Sihota
authors.forename: T
authors.initials: T
authors.lastname: Dada
authors.forename: A
authors.initials: A
authors.lastname: Aggarwal
authors.forename: G
authors.initials: G
authors.lastname: Srinivasan
authors.forename: V
authors.initials: V
authors.lastname: Gupta
authors.forename: V K
authors.initials: VK
authors.lastname: Chabra
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000867:Anterior Chamber / Q000000981:diagnostic imaging / Q000502:physiology*; D001699:Biometry / Q000379:methods; D003430:Cross-Sectional Studies; D005123:Eye / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015812:Glaucoma, Angle-Closure / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D032801:Iridectomy / Q000379:methods; D033401:Microscopy, Acoustic / Q000379:methods; D008875:Middle Aged; D014065:Tonometry, Ocular / Q000379:methods; D016896:Treatment Outcome; D014636:Valsalva Maneuver / Q000502:physiology*