Anterior Segment Optical Coherence Tomography and Angle Closure Glaucoma

Anterior segment optical coherence tomography (AS-OCT) is a non-contact imaging modality, which was developed to obtain cross-sectional images of anterior segment structures including the angle.The advantages of AS-OCT over more traditional methods of examining the angle such as gonioscopy and ultrasound biomicroscopy (UBM) are that it is quick, non-invasive and requires less skill to acquire and interpret images. The current roles of AS-OCT imaging include confirmation of the diagnosis of angle closure and measurement of change in angle width following laser or surgical interventions for angle closure.In regions of the world where angle closure glaucoma is prevalent, AS-OCT has potential as a future screening method for the disease.Currently this technology is limited by having difficulty in identifying important landmarks in the angle due to suboptimal image quality in many cases. This results in apparent over detection of angle closure when compared with gonioscopy and difficulty in applying quantitative measurement parameters in image analysis. Rapid developments in imaging technology including fourier domain OCT and 3-dimensional OCT may help overcome some of these limitations.

Keywords: Anterior segment optical coherence tomography, ultrasound biomicroscopy, angle closure, anterior chamber angle, trabecular meshwork, laser peripheral iridotomy, gonioscopy, peripheral anterior synechiae, iris, lens, glaucoma.