March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
Reproducibility Of Swept Source Optical Coherence Tomography Measurement Of The Iris-trabecular Contact (ITC) Index: A New Parameter For Angle Closure
Author Affiliations & Notes
  • Sue Wei Ho
    Ophthalmology,
    Singapore Eye Research Institute, Singapore, Singapore
  • Mani Baskaran
    Ophthalmology,
    Singapore Eye Research Institute, Singapore, Singapore
  • Ce Zheng
    Ophthalmology,
    Singapore Eye Research Institute, Singapore, Singapore
  • Tin A. Tun
    Clinic,
    Singapore Eye Research Institute, Singapore, Singapore
  • Arun Kumar Narayanaswamy
    Glaucoma,
    Singapore Eye Research Institute, Singapore, Singapore
  • Shamira A Perera
    Ophthalmology,
    Singapore Eye Research Institute, Singapore, Singapore
  • David S. Friedman
    Ophthalmology, Johns Hopkins Wilmer Eye Inst, Baltimore, Maryland
  • Tin Aung
    Glaucoma, Singapore National Eye Center, Singapore, Singapore
  • Footnotes
    Commercial Relationships  Sue Wei Ho, None; Mani Baskaran, None; Ce Zheng, None; Tin A. Tun, None; Arun Kumar Narayanaswamy, None; Shamira A Perera, None; David S. Friedman, None; Tin Aung, None
  • Footnotes
    Support  Translational Clinical Research Partnership (Biomedical Research Council)
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 3264. doi:https://doi.org/
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      Sue Wei Ho, Mani Baskaran, Ce Zheng, Tin A. Tun, Arun Kumar Narayanaswamy, Shamira A Perera, David S. Friedman, Tin Aung; Reproducibility Of Swept Source Optical Coherence Tomography Measurement Of The Iris-trabecular Contact (ITC) Index: A New Parameter For Angle Closure. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3264. doi: https://doi.org/.

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

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Abstract
 
Purpose:
 

To evaluate the inter- and intra-observer reproducibility of measurement of the iris-trabecular contact (ITC) index using swept source optical coherence tomography (SS-OCT; CASIA SS-1000 Tomey).

 
Methods:
 

This was a prospective observational study. All subjects underwent a standardized ophthalmic examination including gonioscopy. SS-OCT scans of one randomly selected eye was captured under strict dark room conditions and constituted acquisition of 128 consecutive meridional scans along 360 degrees. Each eye was scanned 3 times by two experienced operators. Post imaging analysis involved the estimation of the ITC index, a semi-quantitative measure of the degree of angle closure of each imaged eye using in-built software in the imaging device. Sixteen images or frames were used for the measurement of ITC index (Figure 1). The inter- and intra- observer reproducibility was analyzed separately for image grading and image acquisition. Intra-class coefficient (ICC) and the Bland-Altman plot were used to evaluate the agreement between inter and intra-observer reproducibility of the ITC.

 
Results:
 

Twenty-nine patients (29/60 eyes, 48.3% of those enrolled) had angle closure in two or more quadrants on gonioscopy, with a mean age of 65.5 (Standard deviation [SD] 7.1). Study subjects were predominantly Chinese 54/60 (90%) and female (42/60, 70%). The intraclass correlation (ICC) for inter observer reproducibility of ITC was excellent [0.98 (95% confidence interval (CI) = 0.95-0.99)] and the mean difference (95% intervals of agreement) using Bland-Altman test was -0.8 (-7.3,5.7). The ICC for intra observer reproducibility of ITC index was 0.991 (95% CI = 0.96-1.00) and the mean difference and 95% intervals of agreement was -0.8 (-8.2,6.5). The ICC for inter examiner reproducibility of image acquisition was 0.97 (95% CI = 0.95- 0.98) and the mean difference by Bland Altman test was 0.3 (-13.4,13.9)

 
Conclusions:
 

The inter- and intra-observer reproducibility of measurement of the ITC index was excellent using SS-OCT.  

 
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior segment 
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