| Past Issue | Volume 9, Number 1, February 2007 | | Intraobserver and Interobserver Reliability of Measurements of Ultrasound Biomicroscopy Images in Primary Angle Closure Suspects |
Krishna K Ramani, Mani Baskaran, Ronnie George, Joseph Roy, Lingam Vijaya
Sankara Nethralaya, Medical and Vision Research Foundation, Chennai, India
Aim: To evaluate inter- and intraobserver reliability of measurements of ultrasound biomicroscopy images of primary angle closure suspects.
Methods: Ultrasound biomicroscopy images from all quadrants were obtained from 57 primary angle closure suspects between March 2003 and July 2003 at the glaucoma clinic of a tertiary eye care centre. One high-quality ultrasound biomicroscopy image, in which critical anatomical features were clearly visible, was selected for each patient. For interobserver reliability assessments, 2 experienced examiners independently measured 5 parameters of 20 randomly selected images using the calipers in the ultrasound biomicroscopy software. Randomisation was achieved by random clicking of the mouse pointer on the file names in the directory containing the 57 images. The parameters measured were angle opening distance, trabecular meshwork-ciliary process distance, iris thickness, anterior chamber angle, and iridociliary process distance. For intraobserver reliability assessments, these 5 parameters were measured twice in a different set of 25 randomly selected images by one of the examiners. Coefficients of variation were calculated for these observations as a measure of reliability.
Results: Interobserver reliability was rated good (coefficient of variation <10%) for angle opening distance, trabecular meshwork-ciliary process distance, and iris thickness only. Intraobserver reliability was good for all parameters.
Conclusions: Reliable measurements of ultrasound biomicroscopy parameters are possible in patients with narrow angle configuration and reliability is good when a single observer makes repeated measurements of a given ultrasound biomicroscopy image.
Key words: Angle-closure glaucoma, Early diagnosis, Observer variation, Ophthalmologic diagnostic techniques, Ultrasound biomicroscopy Asian J Ophthalmol. 2007;9:13-16.
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