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David C Atherton, Pooja Anand Padgaonkar, Dan Liu, Bonny Lee, Bernard C Szirth, Albert S Khouri; Anterior Segment Optical Coherence Tomography (ASOCT) vs. van Herick Method for Estimating Anterior Chamber Depth in Teleglaucoma Screenings. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5126. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the agreement between ASOCT and van Herick method in estimating angle depth.
Twenty subjects were prospectively enrolled. Average age was 24.5 yo. All were examined using AS-OCT (Optovue, i-Vue OCT) and the van Herick method was estimated from images acquired with slit lamp digital camera (HAAG-STREIT, model 900). Inclusion: Individuals with anterior segments allowing ASOCT and slit lamp digital imaging. ASOCT angle was measured in degrees and the van Herick method was deduced from digital images. Slit lamp images were acquired as per protocol with a thin slit at 45° incidence at the temporal limbus. Anterior chamber depth was compared to corneal thickness (CT). A grade of 0-4 (equivalent to 0°-40° respectively) was assigned based on the depth of the anterior chamber angle (ACA): 4=ACA>1 CT, 3=ACA ¼ - ½ CT, 2 is ¼ CT, 1 is less than ¼ CT, and 0 is no observable angle. Because the van Herick is more subjective, 4 readers masked to one another evaluated van Herick independently. Angle measures were compared using the Pearson correlation, the significance threshold was set at p < 0.05. The intraclass correlation (ICC) was determined for the van Herick method to measure the agreement between four readers.
The mean angle measured by ASOCT was 36.53°. The mean van Herick grade was 3.59 (Table 1). The Pearson correlation of the average van Herick grade and the ACA as measured by ASOCT was weakly positive but did not reach statistical significance (r = 0.318, p = 0.171, Table 2). The ICC between all van Herick readers was 0.835 (95% CI: 0.678-0.927) indicating good agreement.
The van Herick relies on a slit lamp (heavy, not easily transported), is a subjective estimation of the angle, and did not correlate with the actual ACA as measured by ASOCT, an objective test. This makes ASOCT a better choice for telemedicine screenings compared to the van Herick. This pilot study indicates the need for more studies in a more diverse patient population in a teleglaucoma setting.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
Table 1. Average van Herick and OCT.
Table 2. Correlation between AS-OCT and van Herick.
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