Anterior segment imaging: ultrasound biomicroscopy and anterior segment optical coherence tomography

Abstract

Recent advances in ocular imaging have included high-resolution techniques for visualizing the anterior segment and angle structures. This review will describe the two main anterior segment imaging modalities and summarize their applications, strengths and weaknesses. Ultrasound biomicroscopy and more recently anterior segment optical coherence tomography are imaging modalities that can be used to obtain two-dimensional images of the angle and surrounding structures. Ultrasound biomicroscopy has the advantage of being able to illustrate the ciliary body and therefore give clinicians information on nonpupil block mechanisms of primary angle closure and also diagnose other abnormalities such as cyclodialysis clefts. Anterior segment optical coherence tomography is a noncontact and rapid method of imaging the angle and anterior segment that has great potential in the diagnosis and follow-up of patients with angle closure. This article will discuss these and other applications and compare and contrast the two technologies. Rapid advances in anterior segment imaging are enlightening clinicians and researchers to the importance in making the diagnosis of primary angle closure, trying to establish underlying causal mechanisms, and evaluating treatments. Although they do not replace conventional angle and anterior segment examination, they hold great potential for the future.