Fig 1.
The determination of the parameters on an ultrasound biomicroscopy image of the horizontal perpendicular full view scans at the nasal-temporal position centered over the pupil.
ACD = anterior chamber depth; ACW = anterior chamber width; LV = lens vault; PD = pupil diameter; SS = scleral spur.
Fig 2.
The determination of the parameters on an ultrasound biomicroscopy diagram of the radial scans centered over the limbus.
A circle with a radius of 500 μm centered on the scleral spur (SS) is drawn. Angle-opening distance at 500 μm (AOD500) is the distance between the posterior corneal surface and the anterior iris surface on a line perpendicular to the trabecular meshwork 500 μm from the SS. Trabecular-iris space area at 500 μm (TISA500) is the area bounded anteriorly by AOD500 as determined, posteriorly by a line drawn from the SS perpendicular to the plane of the inner scleral wall to the iris, superiorly by the inner corneoscleral wall, and inferiorly by the iris surface. Trabecular-anterior iris surface angle (TAIA) is the angle between the posterior corneal surface and the anterior iris surface (angle of “a-SS-b”). Trabecular-posterior iris surface angle (TPIA) is the angle between the posterior corneal surface and the posterior iris surface (angle of “a-SS-c”). Iris thickness at 500 μm (IT500) is iris thickness at 500 μm from the SS. Iris curvature (IC) is the perpendicular distance from a line between the most central to the most peripheral points of the iris pigment epithelium to the posterior iris surface at the point of greatest convexity. Iris root distance (IRD): the distance from the SS to the insertion location of the iris into the ciliary body (line of “SS-e”). Trabecular-ciliary process distance (TCPD) is a line extending from the corneal endothelium 500 μm anterior to the SS toward the ciliary processes (line of “ad”). Iris-ciliary process distance (ICPD) is the posterior surface of the iris 500 μm anterior to the SS toward the ciliary processes (line of “cd”). Trabecular-ciliary angle (TCA) is the angle between the posterior corneal surface and the anterior surface of the ciliary body (angle of “a-SS-f”). Maximum ciliary body thickness (CBTmax) is the distance from the most inner point of the ciliary body to the inner wall of sclera or its extended line. Ciliary body thicknesses at the point of the SS (CBT0) and at a distance of 500 μm (CBT500) are also measured.
Table 1.
Demographics, clinical features and basic biometric parameters measured by low-coherence interferometry in fellow eyes of acute primary angle closure (Glaucoma) and chronic primary angle closure (Glaucoma).
Table 2.
Intra-observer and Inter-observer intra-class coefficients of the ultrasound biomicroscopy parameters.
Table 3.
Comparison of ultrasound biomicroscopy parameters in fellow eyes of acute primary angle closure (Glaucoma) and chronic primary angle closure (Glaucoma).
Table 4.
Relationship of biometric and ultrasound biomicroscopy parameters with presence of acute angle closures.
Fig 3.
Ultrasound biomicroscopy images of two patients (patient A and B).
A, The fellow eye of a patient with acute primary angle closure (APAC). B, The fellow eye of a patient with chronic primary angle closure (CPAC). Note that the fellow eye of APAC has smaller anterior segment dimensions (anterior chamber depth [ACD] and anterior chamber width [ACW]), higher lens vault (LV) (A1 vs. B1), greater iris curvature (IC), more posterior iris insertion (longer iris root distance [IRD]), and more anteriorly positioned ciliary body (shorter trabecular-ciliary process distance [TCPD] and iris-ciliary process distance [ICPD], and smaller trabecular-ciliary angle [TCA]) (A2 vs. B2). Scale bar: 1mm.