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.

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Comparison of ultrasound biomicroscopic configurations among primary angle closure, its suspects, and nonoccludable angles: the Kumejima Study.

PURPOSE: To quantitatively characterize the ultrasound biomicroscopy (UBM) configurations of the peripheral anterior chamber (AC) in primary angle closure (PAC) and its suspects and to evaluate the diagnostic performance of the UBM parameters to differentiate PAC/PAC suspects in a population-based setting. DESIGN: Cross-sectional study. METHODS: A random 461 of 4632 residents 40 years or older on a southwest island in Japan underwent UBM under light and dark conditions. RESULTS: Of the 374 eligible randomly sampled residents (after excluding 87 with a history of intraocular surgeries, ocular trauma, or iritis; a physical or mental disability making the UBM measurement difficult; or refusal to undergo UBM measurements), reliable UBM images were obtained in 301 right eyes (80.4%). In 45 eyes with PAC/PAC suspects compared to 256 with nonoccludable angles, the angle-opening distance (AOD), trabecular-iris angle (TIA), and trabecular-ciliary process distance (TCPD) under light and dark conditions were smaller (P < .001), while the iris thickness was smaller only under dark conditions (P = .040). Dark-light changes in the AOD and TIA were significantly smaller in the PAC/PAC suspects than in the nonoccludable angles (P < .03); the iris thicknesses did not differ significantly between them. Areas under the receiver operating characteristic curves of the AOD at 500 µm from the scleral spur (AOD500) and TIA in light were 0.94, suggesting these parameters were good for differentiating PAC/PAC suspects. The ideal cutoff values for the AOD500 and TIA under light conditions were 0.17 mm (sensitivity, 0.82; specificity, 0.96) and 15.2 degrees (sensitivity, 0.83, specificity, 0.93), respectively. CONCLUSIONS: Eyes with PAC/PAC suspects had shallow ACs, anteriorly located ciliary bodies, and smaller dark-light changes in the peripheral AC depth, while the iris thickness was similar to that in eyes with nonoccludable angles. The peripheral AC depth under light conditions could most clearly differentiate PAC/PAC suspects from nonoccludable angles.

Ultrasound biomicroscopic configurations of the anterior ocular segment in a population-based study the Kumejima Study.

PURPOSE: To characterize quantitatively the configuration of the anterior ocular segment with ultrasound biomicroscopy (UBM) in a population-based setting. DESIGN: Cross-sectional study. PARTICIPANTS: Ten percent of 4632 residents aged > or =40 years of Kumejima, an island off southwest Japan, were randomly selected. METHODS: We performed UBM under light and dark conditions in the 4 quadrants of the right eyes. The anatomic landmarks on the anterior ocular segment UBM images were identified by 1 examiner to quantify the peripheral anterior chamber depth (ACD), location of the ciliary body, and iris thickness. MAIN OUTCOME MEASURES: Angle-opening distance at 250 and 500 microm from the scleral spur (AOD250, AOD500), trabecular-iris angle (TIA), trabecular-ciliary process distance (TCPD), thickness of the iris (ID), trabecular-anterior iris surface angle (TAIA), trabecular-posterior iris surface angle (TPIA), trabecular-ciliary angle (TCA), and thickness of iris measured at 1000, 2000, and 3000 microm (IT1000, IT2000 and IT3000). RESULTS: The AOD500 averaged 0.267+/-0.138 (mean +/- standard deviation) and 0.202+/-0.116 mm under light and dark conditions, respectively; TIA 22.2+/-10.0 and 17.0+/-8.9 degrees; TCPD 0.755+/-0.165 and 0.748+/-0.152 mm; and ID 0.412+/-0.053 and 0.457+/-0.062 mm. The peripheral ACD was deepest temporally, then nasally, then inferiorly, and then superiorly (P<0.05, post hoc test). The position of the ciliary body was deepest nasally, then temporally, then inferiorly, and then superiorly (P<0.05). Iris thickness did not differ significantly among the quadrants. Older subjects had a shallower peripheral ACD, more anteriorly located ciliary body, and thinner iris (analysis of covariance, P<0.015). The peripheral ACD was deeper and the ciliary body was located more deeply in men than women (P<0.05), although no intergender differences in iris thickness were seen (P>0.1). Hyperopia, short axial length, and shallow central ACD were significantly correlated with shallower peripheral ACD, anteriorly located ciliary body, and thinner iris (P<0.05). Elevated intraocular pressure was associated with a shallow peripheral ACD (P< or =0.043). CONCLUSIONS: There are significant associations of the peripheral ACD, location of the ciliary body, and iris thickness with age, gender, refractive error, axial length, and intraocular pressure.