Optical coherence tomography (OCT) is an outstanding example of applied physics in medicine. Over the last decade, OCT has become an essential tool in ophthalmology. OCT is a low-coherence, interferometer-based, noninvasive medical imaging modality that can provide noncontact, high-resolution, cross-sectional images of biological tissue. Optical coherence tomography has become indispensable in the armamentarium of retinal physicians. This imaging technique provides cross-sectional images of the retina, for identifying, monitoring and quantitatively assessing diseases of the macula and the optic nerve head. Optical coherence tomography can be used to visualize changes in tissue optical scattering properties or refractive index discontinuities, but it cannot distinguish between tissues of similar optical properties. By comparison, histology visualizes tissue according to specific staining properties. Optical coherence tomography is a field in rapid evolution. Interpretation of OCT images has also advanced, primarily because of improvement in the quality of the images produced, higher resolution and accumulated clinical experience. Macular dystrophy shows great variability in severity and rate of progression. Cone disease presents with decreased visual acuity and poor color discrimination. OCT, in such cases, reveals foveal atrophy.