Prevalence of plateau iris in primary angle closure suspects an ultrasound biomicroscopy study

Ophthalmology. 2008 Mar;115(3):430-4. doi: 10.1016/j.ophtha.2007.07.026. Epub 2007 Sep 27.


Purpose: To determine the prevalence of plateau iris in a cohort of primary angle closure suspects (PACSs) using ultrasound biomicroscopy (UBM).

Design: Cross-sectional observational study.

Participants: Subjects over the age of 50 years diagnosed as PACSs.

Intervention: Subjects were randomized to undergo laser peripheral iridotomy (LPI) in one eye. Ultrasound biomicroscopy was performed before and a week after LPI.

Main outcome measures: Ultrasound biomicroscopy images were qualitatively assessed using standardized criteria. Plateau iris was defined in a quadrant by the presence of an anteriorly directed ciliary body, an absent ciliary sulcus, a steep iris root from its point of insertion followed by a downward angulation from the corneoscleral wall, presence of a central flat iris plane, and irido-angle contact. At least 2 quadrants had to fulfil the above criteria for an eye to be defined as plateau iris.

Results: Two hundred five subjects were enrolled; UBM images of 167 subjects were available for analysis. Plateau iris was found in 54 of 167 (32.3%) PACS eyes after LPI. Quadrantwise analysis showed that 44 of 167 (26.3%) eyes had plateau iris in 1 quadrant, 36 (21.5%) in 2 quadrants, 16 (9.5%) in 3 quadrants, and 2 (1.2%) in all 4 quadrants. Plateau iris was most commonly observed in the superior and inferior quadrants.

Conclusions: Using standardized UBM criteria, plateau iris was found in about a third of PACS eyes after LPI. Prospective longitudinal studies are required to determine the clinical significance of this finding for the management of PACSs.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Ciliary Body / diagnostic imaging
  • Cross-Sectional Studies
  • Female
  • Glaucoma, Angle-Closure / diagnostic imaging*
  • Glaucoma, Angle-Closure / epidemiology*
  • Glaucoma, Angle-Closure / surgery
  • Gonioscopy
  • Humans
  • Intraocular Pressure
  • Iridectomy / methods
  • Iris Diseases / diagnostic imaging*
  • Iris Diseases / epidemiology*
  • Iris Diseases / surgery
  • Laser Therapy / methods
  • Male
  • Microscopy, Acoustic*
  • Middle Aged
  • Prevalence
  • Prospective Studies
  • Reproducibility of Results