April 2009
Volume 50, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2009
Expert Assessment of Primary Angle Closure Mechanisms using Anterior Segment Optical Coherence Tomography
Author Affiliations & Notes
  • A. Tan
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • M. D. Aquino
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • J. L. S. See
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • D. Law
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • S.-Y. Koay
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • S. Loon
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • P. T. K. Chew
    Ophthalmology, National Univ Hosp Singapore, Singapore, Singapore
  • Footnotes
    Commercial Relationships  A. Tan, None; M.D. Aquino, None; J.L.S. See, None; D. Law, None; S.-Y. Koay, None; S. Loon, None; P.T.K. Chew, None.
  • Footnotes
    Support  None.
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 3351. doi:
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      A. Tan, M. D. Aquino, J. L. S. See, D. Law, S.-Y. Koay, S. Loon, P. T. K. Chew; Expert Assessment of Primary Angle Closure Mechanisms using Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3351.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To determine the agreement of four glaucoma specialists in identifying the underlying mechanisms of primary angle closure using anterior segment optical coherence tomography (ASOCT) and distinguish the common mechanism involved in angle closure.

Methods: : Four glaucoma experts independently evaluated nasal-temporal ASOCT images captured in the dark of primary angle closure and primary angle closure glaucoma eyes. The images were categorized according to the following mechanisms of angle closure: pupil block, plateau iris contour, large anteroposterior lens diameter, thick peripheral iris roll and creeping angle closure. The responses gathered from the four observers were analysed by 2 separate individuals blinded to each other’s data entry. Kappa coeffecient was calculated to determine agreement between observers. Results were analyzed statistically using SPSS 15.

Results: : There were one hundred fifty eight (158 ) angle closure images reviewed. The strength of inter-observer agreement was very good (see Table 1 ). Only 28 out of 158 scans (17.7% ) showed the presence of only one mechanism underlying the angle closure. The remaining ASOCT images (82.3%) were classified as having a combination of 2 to 4 mechanisms. A large lens was the most frequent mechanism underlying angle closure in these subjects.(119 out of 158 images) followed by pupil block (72 out of 158). Peripheral iris roll (68 out of 158) appeared as 3rd and plateau iris (51 out of 158) was the 4th commonly seen mechanism.

Conclusions: : Lens mechanism and pupil block were identified as the frequent elements involved in angle closure based on strong inter-observer agreement in identifying angle closure mechanisms by ASOCT.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical 
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