Imaging of the anterior segment in glaucoma.

Although constituting only about a quarter of all glaucoma, angle closure glaucoma causes a disproportionate amount of visual morbidity and is predicted to be responsible for almost half of bilateral blindness by 2020. Early detection and treatment of angle closure significantly improves visual prognosis. Identification of eyes at risk of angle closure currently relies on opportunistic case detection, often by gonioscopy. However, gonioscopy is a highly subjective technique and often leads to misdiagnosis and underdetection of angle closure. More recently, various imaging modalities that allow a more objective assessment of the anterior segment structures, including anterior segment optical coherence tomography and the scanning peripheral anterior chamber depth analyser, have come under close scrutiny for their potential in screening for angle closure. Their accuracy and repeatability, advantages and disadvantages as well as their ease of use are all important to consider whether they are intended for use in the clinical setting or if they are to be incorporated into mass screening programs. Furthermore, their place alongside gonioscopy and more established technologies such as ultrasound biomicroscopy must be considered. The aim of this paper is to review the anterior segment imaging technologies that are currently available.