Anterior Segment OCT: Angiography

Abstract

Optical coherence tomography angiography (OCTA) is a non-invasive technique for imaging vasculature in the eye. In the anterior segment, OCTA can produce both cross-sectional and three-dimensional images that allows for imaging of normal structures or pathology with its accompanying vasculature. Currently, imaging of the anterior segment vasculature is not routinely performed due to the risks associated with invasive dye-based angiography usually performed for the posterior segment. Thus, anterior segment OCTA (AS-OCTA) has the potential for future clinical applications such as diagnosis of corneal, iris, conjunctival, and scleral pathologies, preoperative surgical planning for corneal vascularization, assessment of new antiangiogenic therapeutics, and evaluation of treatment for limbal stem cell deficiency or corneoscleral inflammation. However, as current OCTA systems are optimized for assessment of the posterior segment of the eye, using OCTA for anterior segment imaging has several limitations. In this chapter, we summarize the recent developments and clinical applications in anterior segment OCTA (AS-OCTA) imaging for the cornea, iris, sclera, and conjunctiva. In addition, we describe the commercially available OCTA systems, discuss the limitations of adapting current OCTA technology for the anterior segment, and propose possible future directions for AS-OCTA imaging. With further advancement in the software and hardware, AS-OCTA may become a useful addition to the current diagnostic armamentarium for anterior segment diseases in the near future.