**1. Introduction**

Optical coherence tomography (OCT) is a high-resolution, cross-sectional imaging technique. It is fast, safe and non-invasive modality. Over the past 25 years, OCT has advanced to become the most commonly used investigative tool in ophthalmology. The 3D imaging allows qualitative and quantitative structural analysis of different locations in the retina and optic nerve head. It helps not only to improve the diagnosis but also to understand the pathogenesis of various diseases and to evaluate the effect of the implemented therapies.
