Currently, a number of OCT machines are available, practically all based on ‘Spectral Domain’ technology to allow faster scanning rates typically 25,000 to 40,000 scans/second. High-resolution images are obtained in real time, which have ‘point-to-point’ registration with the fundus image obtained with a confocal scanning technology. Thus, it has become a remarkable tool to follow structural changes not only in patients with macular disease but importantly in glaucoma as well. While these are exciting times in the field of OCT technology and its applications what with new information becoming available practically everyday, we would like to share our early experiences obtained in the last 2 years of using the new ‘Spectral Domain’ OCT in this thoroughly revised 3rd edition of the book. It finds extensive application in diagnosis, management and follow-up of introduction to optical coherence tomography, OCT equipment, Technique of acquiring OCT, selection of scan protocols, interpretation of OCT scan, diabetic macular edema, idiopathic central serous chorioretinopathy, macular hole, retinal vascular occlusions, retinal vasculitis, epiretinal membranes, age-related macular degeneration, OCT in choroidal neovascular membranes, juxtafoveal telangiectasia, heredodystrophic disorders, foveal hemorrhage, photic maculopathy, optic disc pits, inflammatory diseases of retina-choroid, retinal angiomatosis proliferation, retinal trauma, macular evaluation following retinal detachment surgery, degenerative myopia, postoperative endophthalmitis, glaucoma, case illustrations, spectral domain OCT for glaucoma and many more areas that are divided into 31 chapters. For ease of comprehension, provide with brief case summaries, fundus photographs, fluorescein angiography and the OCT images and the follow-up images for most of the patients.