Evaluation of anterior chamber angle by van Herick grading and ultrasound biomicroscopy in light and dark conditions for finding appositional angle closure and plateau iris configuration.

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To evaluate association of the van Herick (VH) grades with the ultrasound biomicroscopic (UBM) parameters, appositional irido-trabecular contact (A-ITC) and plateau iris (PI) in a randomly sampled population. A 10% random sample of all residents aged 40 or older of the Kumejima study underwent UBM under dark and light conditions in the four quadrants of right eyes. Of 301 right eyes with eligible UBM images, 101 (33.6%) and 200 (66.4%) were classified as VH≤2 and VH≥3, respectively. The UBM parameters on angle width and ciliary body configuration were significantly different between VH≤2 and VH≥3 eyes (p<0.001). A-ITC was found in at least one quadrant in 54.5% and 75.2% of VH≤2 eyes under light and dark conditions, respectively; and 20.5% and 45.5% of VH≥3 eyes. When 'VH≤2' was used to screen eyes with A-ITC in three or more quadrants, the sensitivity and specificity were 74.1% and 75.3%, respectively. A-ITC was significantly associated with shallower anterior chamber (p=0.018) and higher intraocular pressure (p=0.044) in VH≥3 eyes. Plateau iris (PI) was found in 15.8% and 6.0% of VH≤2 and VH≥3 eyes, respectively. Plateau iris (PI) was significantly associated with the UBM parameters on angle width and ciliary body configuration. When 'VH≤2' was used to screen eyes with PI, the sensitivity and specificity were 57.1% and 68.9%, respectively. The VH grade of ≤2 and ≥3 showed significant association with UBM angle width and ciliary body configuration parameters. The VH≤2 criterion should be useful for screening of A-ITC and PI.