Comparing Angle Dimensions Using Gonioscopy, Artemis, and Pentacam

Abstract

Purpose: : To determine if subjective grading of angle dimensions by gonioscopy is comparable to objective measures of angle dimensions using very high-frequency ultrasound (Artemis) and Oculus-Pentacam.

Methods: : In this pilot study, 12 eyes of 6 healthy volunteers have been enrolled to date. Gonioscopy was performed using a Goldman 4-mirror lens and a subjective measurement of the angle size in degrees in 4 quadrants was taken. All gonioscopy was performed by a fellowship trained glaucoma specialist. The subjects next had their anterior chambers scanned and their angle size was measured using first the Oculus-Pentacam and then the Artemis in the nasal quadrant.

Results: : Measurements using gonioscopy compared to Artemis angle measurements correlated well (r=0.94, p<0.001). In contrast, angle measurements using i) gonioscopy compared to Pentacam did not correlate well (r=0.84, p<0.001) and ii) Pentacam compared to Artemis angle measurements did not correlate well (r=0.85, p<0.001). Analysis of variance showed a significant difference did exist among the three modalities of angle measurement (F_3.24=53.78, P<0.0001). Bland-Altman plots were used to compare the measurements using the three modalities. On average, Artemis overestimated angle measurements compared to gonioscopy by 5.8 ± 4.1 degrees. Similarly, Pentacam overestimated angle measurements compared to gonioscopy by 12.2 ± 11 degrees. If Artemis angle measurements are compared to Pentacam measurements, on average the Pentacam produced values 9.3 ± 5.0 degrees larger than Artemis.

Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior segment