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S. P. Deokule, G. Vizzeri, L. M. Alencar, R. N. Weinreb, F. A. Medeiros; Comparison of Anterior Chamber Angle Measurements Using Unenhanced and Enhanced Imaging Protcols for Visante Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3348.
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To evaluate the reproducibility and intra and inter-observer agreement of anterior chamber angle measurements acquired using un-enhanced and enhanced imaging protocols for Visante anterior segment optical coherence tomography (AS-OCT).
The anterior segments of 30 eyes (15 OD, 15 OS) of 15 healthy subjects (mean age 33.8±13.0 years, 8 females) were imaged on AS-OCT using an un-enhanced imaging protocol followed by an enhanced imaging protocol within a single session. Anterior chamber angle measurements were measured by two masked observers independently, on two separate occasions. Angle measurements included angle width, angle-opening distance (AOD), trabecular-iris space area (TISA) and angle recess area (ARA) at 500 µm and 750 µm distance from the scleral spur. Coefficients of variation (CV) and intra-class correlation coefficients (ICC) were calculated to evaluate reproducibility of the measurements and Bland Altman plots were constructed to assess the agreement within two measurements taken by the same observer (intra-observer agreement) and between measurements taken by different observers (inter-observer agreement).
In general, the CVs and ICCs calculated were similar for the un-enhanced and enhanced imaging protocols. Amongst the measured parameters, the angle width was the most reproducible with CVs of 5.6% and 6.0% and ICC of 0.85 (95% CI 0.70 - 0.88) and 0.81 (95% CI 0.70 - 0.88) while ARA 500 was the least reproducible with CVs of 13.1% and 15.1% and ICC of 0.85 (95% CI 0.76 - 0.91) and 0.73 (95% CI 0.59 - 0.83) for the un-enhanced and enhanced protocols, respectively for operator 1. Intra-observer and inter-observer agreement was similar for all the parameters evaluated (e.g., intraobserver and inter-observer 95% limits of agreement for un-enhanced angle width were -7.0 - 13.9 and -16.3 - 7.5, respectively).
Both the un-enhanced and enhanced protocols were found to be equally reproducible. In general, the reproducibility of the AS-OCT parameters was good and the agreement consistent within and between operators, with angle width being the most reproducible parameter. Further studies are needed to determine whether AS-OCT can be a potentially useful tool for glaucoma screening.
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