 Optical coherence tomography OCT has become a critical component to the evaluation of ophthalmic disease. Similar to the ultrasound, OCT uses light to reconstruct an image of the tissue of interest. In effect, OCT functions almost like a light biopsy, allowing clinicians to visualize subtle changes in the tissue, such as macular edema or subretinal fluid. OCT in the clinic setting has become the gold standard for monitoring diseases such as macular degeneration and diabetic retinopathy;and it has become one of the most frequently ordered diagnostic test in ophthalmology. 