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Frode Larsen, Knut Luraas, Per Lundmark; Anterior Chamber Angles measured by van Herick’s Method and Anterior Segment Optical Coherence Tomography (OPKO Spectral OCT SLO™) in Patients seen in Optometric Practice in Norway. Invest. Ophthalmol. Vis. Sci. 2013;54(15):891.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate i) the distribution of anterior chamber angles measured by means of van Herick’s method and anterior segment optical coherence (AS-OCT) in optometric patients in Norway, ii) the agreement between these methods for angle measurements.
300 patients over the age of 18 and with no general- or ocular pathology were consecutively enrolled from two optometric practices in Norway during a period of 8 months. All underwent a full optometric examination followed by standardized measurements of the temporal- and nasal anterior chamber angle (ACA) using van Herick’s method and AS-OCT (OPKO Spectral OCT SLO™) in randomized order by two experienced optometrists. ACA was graded and the peripheral chamber depth (PCD) was estimated in quarter steps of the corneal thickness by van Herick’s method. The trabeculo-iris angle (TIA) was measured in degrees (deg) with AS-OCT using the integrated analyze software (v.1.87) and averaged for 3 scans. Temporal- and nasal ACAs were analyzed separately for both eyes. Analyses of distribution and correlation were by descriptive- and Pearson and Spearman statistics. Agreement of detection of narrow angles (<= 20 deg) between the two methods was tested using kappa statistics.
3 months into the study 156 eyes of 78 patients were included (F: 54, mean age 56.2 yrs). Mean temporal- and nasal TIA was 28.1 deg (range 3.5 - 58.1) and 27.7 deg (range 6.6 - 61.0), respectively while the distribution of ACA grading (G) with corresponding mean TIA was G0: 0 %, G1: 1.9 % (7.7 deg), G2: 9.0 % (22.5 deg), G3: 31.4 % (24.7 deg) and G4: 57.7 % (31.6 deg) for the temporal segment and G0: 0 %, G1: 0.6 % (8.3 deg), G2: 8.3 % (19.0 deg), G3: 31.4 % (25.1 deg) and G4: 59.6 % (31.6 deg) for the nasal segment. TIA correlated significantly with ACA grading r = 0.36 - 0.40 (p < 0.01) and with PCD measurement r = 0.51 - 0.60 (p < 0.01). Kappa was 0.28 and 0.24 for temporal and nasal segments, respectively.
This is the first report on the distribution of chamber angles measured by means of van Herick’s method and AS-OCT in optometric practice in Norway. Results indicate that measurements of ACA with AS-OCT correlate with gradings of ACA and measurements of PCD with van Herick’s method, however, with poor agreement between the methods for discrimination of narrow angles.
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