**Abstract**

OCT is a high-resolution, non-invasive imaging technique that relies on time-of-flight information. Different patterns such as time domain and spectral domain were implemented until the introduction of the longer wavelength new generation, swept-source OCT. Anterior segment OCT has different implications as AC angle assessment, tear meniscus measurement, corneal pathologies, etc. In posterior segment, macular lesions are easier to image (vitreoretinal interface, intraretinal changes, subretinal and choroidal pathologies). OCT-ON is an important tool in investigating glaucoma and optic neuropathies. Recent advances made OCT indispensable tool in everyday practice. Functional extension providing information on retinal and choroidal circulations without the need for dye injection is the OCT angiography. ONH-OCTA and AS-OCTA imaging vasculature are useful for various clinical applications, ranging from diagnosis to treatment with many challenges. Major advances occurred in the intraoperative OCT, from portable probe to the microscope-integrated system and handheld type. Developing technologies are coming as doppler OCT, in-vivo retinal images and polarization-sensitive OCT.

**Keywords:** OCT, time-domain, spectral domain, swept source, intraoperative OCT
