Repeatability and comparison of clinical techniques for anterior chamber angle assessment

Abstract

This is the accepted version of the paper.This version of the publication may differ from the final published version. Coherence Tomography (AS-OCT) and determine the agreement between these techniques within a community optometry setting. Permanent repository link MethodsGonioscopy, van Herick method and AS-OCT imaging were performed by an optometrist on two occasions, one month apart, on 80 subjects aged over 40 years recruited from community optometry practices. Anterior segment images were captured with a spectral domain OCT (Topcon 3D OCT-2000; wavelength 840nm) set to the Anterior Segment (AS) mode. Eyes were graded as open or occludable for each method. AS-OCT images from both visits were graded by a second optometrist masked to the gonioscopy and van Herick method results, and the visit on which the images were acquired. Cohen's kappa (κ) was used to describe the intraobserver repeatability. Likelihood ratios, sensitivity and specificity of van Herick method and AS-OCT were calculated, using gonioscopy as the reference standard. ResultsMeasurements were obtained from 80 eyes of 80 subjects. In four cases, AS-OCT images were un-gradable due to difficulty in locating the scleral spur. The repeatability of gonioscopy was fair κ=0.29, while that of the van Herick method (κ=0.54) and AS-OCT (κ=0.47) were somewhat better. The van Herick method showed good sensitivity (visit 1: 75%, visit 2: 69%) and high specificity (visit 1: 88%, visit 2: 96%). The sensitivity of AS-OCT was fair (visit 1: 46%, visit 2: 25%), but specificity was high (visit 1: 87%. visit 2: 89%). ConclusionIntra-observer repeatability was better for van Herick method and for AS-OCT than for gonioscopy, despite the latter being considered the gold standard method. The van Herick method appeared to be more sensitive than AS-OCT when identifying eyes at risk of angle closure. A standalone anterior segment OCT with a longer wavelength laser could afford better visualisation of the angle, and might therefore be expected to enable the examiner to make more precise classifications. These instruments are not widely used by optometrists in clinical practice in the UK at present.

Agreement between Gonioscopic Examination and Swept Source Fourier Domain Anterior Segment Optical Coherence Tomography Imaging

“…This is consistent with the reported literature [7, 21]. Although gonioscopy has traditionally been the gold standard for grading ACAs, given the intraobserver (intervisit) agreements found in our study and those published by Campbell et al [10], it is not clear that it is a more reliable representation of the true angle status as open or narrow when compared to ASOCT, which may be the result of examiner technique or dynamic anatomic variation in the individual.…”

“…Intraobserver (intervisit) kappas were 0.57 and 0.83 for readers 1 and 2, respectively, in our study, which was better than previously published results (kappa = 0.47) using the spectral domain Topcon OCT (Topcon Europe Medical BV, Netherlands) in the anterior segment mode (840 nm wavelength) [10]. …”

“…With the technical limitations of gonioscopy, we thought this might be an interesting parameter to evaluate the consistency of the individual examiner on different visits with the same patient, which was higher than the agreement reported by Campbell et al (kappa = 0.29), the only reference we found for a study evaluating intraobserver agreement for gonioscopy [10]. Given the coordination it took to evaluate intraobserver agreement, we can understand why there is a paucity of existing literature.…”

“…Often, the methodology in the published literature on ASOCT and gonioscopy does not indicate which angle specifically was used for the gonioscopic classification. When indicated, most published studies compared superior quadrant gonioscopy with nasal/temporal meridian ASOCT images, which cannot be assumed to be equivalent, especially in eyes with PAC [8, 10, 11]. A few studies have compared gonioscopy to superior/inferior angles with visible scleral spur but have excluded 20–95% of imaged eyes [6, 7, 9, 12, 20].…”

Role of anterior segment optical coherence tomography in angle‐closure disease: a review

“…The repeatability of gonioscopy was fair (κ = 0.29), while that of AS-OCT (κ = 0.47) was better. 21 The identification of the scleral spur location represents an important anatomical landmark for the evaluation of angle closure. Sakata et al observed that the scleral spur location could not be detected in approximately 30% of the anterior chamber angle images obtained with the Visante AS-OCT.…”