OCT Biomicroscopy is the use of optical coherence tomography (OCT) in place of slit lamp biomicroscopy to examine the transparent axial tissues of the eye. Traditionally, ophthalmic biomicroscopy has been completed with a slit lamp biomicroscope that uses slit beam illumination and an optical microscope to enable stereoscopic, magnified, cross-sectional views of transparent tissues in the eye, with or without the aid of an additional lens. Like slit lamp biomicroscopy, OCT does not penetrate opaque tissues well but enables detailed, cross-sectional views of transparent tissues, often with greater detail than is possible with a slit lamp. Ultrasound biomicroscopy (UBM) is much better at imaging through opaque tissues since it uses high energy sound waves. Because of its limited depth of penetration, UBM's main use within ophthalmology has been to visualize anterior structures such as the angle and ciliary body. Both ultrasound and OCT biomicroscopy produce an objective image of ocular tissues from which measurements can be made. Unlike UBM, OCT biomicroscopy can image tissues with high axial resolution as far posteriorly as the choroid (Figure 1). Rationale Biomicroscopes have been a staple of the ophthalmic examination for nearly a century. The addition of slit beam illumination to a horizontally-mounted stereo microscope enables users of a slit lamp biomicroscope to optically 'slice' through transparent tissues in the eye to see them in cross section. Stereoscopic magnification further enables highly detailed inspection of ocular tissues. The use of lenses, such as the Hruby lens, contact lenses or handheld 90D or 78D diopter lenses enables magnified inspection of posterior structures such as the retina. Despite their relative ubiquity, slit lamps have several important limitations. As optical instruments, conventional slit lamp biomicroscopes do not natively record or document exam findings in the way that imaging devices, such as OCT, MRI or CT, do by storing images. Some modern slit lamps now have the ability to record 2D video or still digital images during an exam. Without any objective record of the exam, findings from slit lamp exams are transient and must be interpreted in real-time by a trained observer. Exam data can be lost if the examiner fails to document a finding or does not have the knowledge required to recognize a finding - a limitation that can be amplified by the variability in ophthalmic training around the world. This requirement that the operator be knowledgeable also means that slit lamp exams must be