Optical coherence tomography (OCT) is a noncontact noninvasive technology providing high-resolution, cross-sectional images of the eye. It is an optical imaging system providing in vivo imaging of the retina analogous to B scan. Its use in retina and glaucoma has been steadily growing. Its use for glaucoma diagnosis and in vivo capabilities of retinal nerve fiber layer (RNFL) and optic nerve head (ONH) analysis has revolutionized the previous uncertain diagnostic challenges into an accurate and precise diagnosis. This chapter covers the basic principles of OCT, importance of OCT in glaucoma, instrumentation, clinical uses, scans, different analysis protocols in glaucoma, RNFL thickness analysis, optic nerve head analysis, macular thickness analysis, optic disk scan, fundus image, TSNIT thickness profiles, normative database, advantages of OCT, disadvantages of OCT, and the future.