In clinical practice, anterior segment OCT cannot replace gonioscopy as a method of examining the filtration angle

The science behind the tip

The diagnosis and management of all types of glaucoma is dependent on the accurate evaluation of the angle and its structures. Dynamic gonioscopy is essential in distinguishing the various degrees of angle closure.

In the past few years anterior segment OCT (AS OCT) has become popular, as it provides non-contact examination of the angle and quantitative measurement of the various structures (1). This biomechanical analysis is useful for scientific purposes, but provides limited information in the individual patient. Disadvantages of this technology include: an inability to identify the scleral spur (which is an essential landmark for the interpretation of the examination) in approximately 25% of AC OCT images and an inability to perform a dynamic examination, because the scan is undertaken in only one plane/axis (2).

When AS OCT is used for screening for primary angle closure, the test does not achieve the combination for specificity and sensitivity needed (3). In the setting of an ophthalmic clinic, gonioscopy remains the best method of detecting these patients.

Contributor: Dr Christoph Faschinger MD PhD, Graz AUT

References:

1. Kim DY, Sung KR, Kang SY et al. Characteristics and reproducibility of anterior chamber angle assessment by anterior-segment optical coherence tomography. Acta Ophthlamol 2009; 89: 435-44.

2. Narayanaswamy A, Sakata LM, He MG et al. Diagnostic performance of anterior chamber measurements for detecting eyes with narrow angles: an anterior segment OCT study. Arch Ophthalmol 2010; 128: 1321-27.

3. Zhang Y, Li SZ, Li L et al. The Handan Eye Study: Comparison of screening methods for primary angle closure suspects in a rural Chinese population. Ophthalmic Epidemiol 2014;21: 268-75.

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