Abstract
Purpose:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
Keywords: 420 anterior chamber •
465 clinical (human) or epidemiologic studies: systems/equipment/techniques