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W.-B. Khor, R. Lavanya, L. M. Sakata, T. Aung; Evaluation of Scanning Protocols for Anterior Segment Optical Coherence Tomography Imaging of the Angle. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3347.
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To assess the diagnostic performance of different anterior segment-optical coherence tomography (AS-OCT) scanning protocols in detecting eyes with angle closure.
This was a cross-sectional observational study involved 2104 subjects from a community clinic in Singapore who were over 50 years of age and had no previous ophthalmic problems. Gonioscopy was performed by a single masked examiner, and an anatomically narrow angle (ANA) was defined in eyes in which the posterior trabecular meshwork could not be seen in two or more quadrants. AS-OCT imaging was performed by a single masked operator using the commercially available Visante-OCT (Carl-Zeiss Meditec, Dublin/USA). Three AS-OCT images of the anterior chamber angle (ACA) were obtained in dark conditions: 1 image scanning the angle at the 3 and 9 o’clock hour positions, 1 scanning the superior angle at 12 o’clock, and 1 scanning the inferior angle at 6 o’clock. AS-OCT images were assessed by two examiners with glaucoma subspecialty training working together, and a closed ACA was defined by any contact between the iris and angle wall anterior to the scleral spur.
AS-OCT images of all four quadrants could be subjectively graded in 1853 right eyes. A total of 380 eyes were found to have ANA on gonioscopy. Table shows the diagnostic performance of different AS-OCT scanning protocols in detecting ANA eyes. Scanning just the nasal-temporal quadrants (horizontal scan) resulted in the lowest sensitivity, while performing vertical scans alone had similar performance to scanning all 4 quadrants.
The diagnostic performance of AS-OCT varied according to the adopted scanning protocol. Scanning just the vertical quadrants was as effective as scanning all quadrants in detecting angle closure. Imaging only the nasal and temporal quadrants, although technically easier to perform, may result in missing cases of angle closure.
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