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Xin Yang, Yue Shi, Kenneth Marion, Brian Francis, Srinivas R Sadda, Vikas Chopra; Correlation between Anterior Segment OCT and Novel 360o Angle Imaging. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5549.
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Previous studies have reported on the correlation between a clinician’s subjective gonioscopy grading compared to objective anterior chamber angle (ACA) parameters from various anterior-segment OCT (ASOCT) devices. Now, a novel iridocorneal-angle imaging system (Gonioscope) has been introduced which can provide a complete 360o color photo of the angle which may facilitate standardized gonioscopy. The objective of this study was to compare angle assessments derived from gonioscope photos with ASOCT-derived ACA metrics.
Twenty-five eyes (100 quadrants) from 16 normal participants and 29 eyes (94 quadrants) from 17 patients with POAG or PACG imaged with the Gonioscope (GS-1, Nidek) and ASOCT (Zeiss Cirrus 5000). With the GS-1, 360° ACA images were obtained in all eyes. For the ASOCT, at least one 5-line raster image set was obtained from the ACA at four different locations (3, 6, 9, and 12 o’clock positions). Images from both modalities were reviewed by 2 masked, certified Doheny Image Reading Center graders. For the ASOCT ACA scans, Image J was used to measure the angle opening distance at Schwalbe’s line (AOD-SL) and the Trabecular-Iris Space Area at Schwalbe’s line (TISA-SL). In GS-1, the angle was assessed at the four corresponding quadrants, namely the superior, inferior, nasal and temporal quadrants, using the Shaffer angle grading system. Spearman’s correlation was performed to assess correlation between AOD-SL/TISA-SL and Shaffer grade.
Of the total 194 quadrants which were assessed, 187 quadrants were graded to be of high image quality for both the AS-OCT and Gonioscope images, and were included in the final analysis. A strong correlation was observed between AS-OCT ACA metrics and the gonioscope-derived Shaffer grades. Correlation coefficients between AOD-SL/TISA-SL and Shaffer grade were 0.727 and 0.727, respectively. The correlations in the horizontal quadrants (AOD-SL 0.728, TISA-SL 0.735) were similar to that of the vertical quadrants (AOD-SL 0.734, TISA-SL 0.731). The correlations in glaucomatous eyes (0.640 AOD-SL and 0.628 TISA-SL) were stronger than in the normal (0.560 AOD and 0.568 TISA).
A strong correlation was observed between gonioscope-derived angle grades and ASOCT-derived ACA metrics. The gonioscope warrants further evaluation as a diagnostic tool to yield more accurate and reliable assessments of the angle.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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