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Maria Fernanda Dominguez Velasco, Vikas Chopra, Zhou Yuan Zhang, Juan-Carlos Gutierrez-Hernandez, Muneeswar G. Nittala, Brian Francis, Srinivas R. Sadda; Comparison Of Anterior Chamber Angle Metrics Obtained Using Time Domain Versus Spectral Domain Optical Coherence Tomography And Varying Angle Reference Landmarks. Invest. Ophthalmol. Vis. Sci. 2012;53(14):3275.
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© ARVO (1962-2015); The Authors (2016-present)
To compare anterior chamber angle(ACA)measurements obtained using time domain optical coherence tomography(OCT)with the scleral spur(SS)as the reference landmark and spectral domain(SD)OCT with Schwalbe’s Line(SL)as the reference
A prospective IRB approved study was conducted enrolling patients with open angle from the glaucoma clinic at the Doheny Eye Institute. All subjects underwent gonioscopic evaluation by a glaucoma specialist using the modified Shaffer’s grading system to rate angle width.A narrow angle was defined as Shaffer grade ≤2 in ≥3 quadrants, and such patients were excluded.Subjects with evidence of peripheral anterior synechiae, history of a traumatic cataract and/or angle recession, argon laser trabeculoplasty,iridoplasty or iridotomy were excluded. For eligible subjects, the undilated inferior ACA of both eyes was imaged with Cirrus HD-OCT(Anterior Segment 5 Line Raster) and Visante AS-OCT(270º Inferior Angle). All OCT scans were acquired by a single trained examiner in a darkened room. Poor quality images due to motion artifact, poor focus were excluded. For Visante based measurements, the angle metric tools provided by the instrument were used for analysis to identify the SS and compute the angle opening distance(AOD)-500, AOD-750, trabecular iris space area(TISA)-500, and TISA-750. For SD-OCT imaging, improved visualization of SL, allowed calculation of novel metrics: SL-AOD and SL-TISA. The SD-OCT derived measurements were compared with the traditional Visante angle metrics and gonioscopic angle gradings
Eighty-six eyes from 45 subjects were included. We excluded 10 eyes(11.6%)due to insufficient image quality. By gonioscopy(inferior angle rating only), 8%were rated as Shaffer grade 2, 37%grade 3 and 55%grade 4.The AS-OCT angle parameters showed good correlation with gonioscopic grading(r=0.336,p=0.003).The mean inferior ACA metrics as determined by Visante were AOD-500 0.46±0.18, AOD-750 0.65±0.26, TISA-500 0.16±0.06, TISA-750 0.30±0.11 and by HD-OCT were SL-AOD 0.65±0.26 and S-TISA 0.24±0.11. The AOD-500(r=0.70,p<0.001)and AOD-750(r=0.64,p<0.001)were significantly correlated with SL-AOD, although the AOD-750 showed better agreement(mean difference: 0.18±0.13 of compared with 0.21±0.16 for AOD-500)
The improved and consistent visualization of SL afforded by SD-OCT allows computation of novel angle metrics based on this landmark. Some of these parameters show good agreement with historical Visante OCT derive measures(e.g.AOD-500).SD-OCT derived angle metrics and may be useful for future studies characterizing angle structures and geometry
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