The OCT is an incredibly sensitive instrument that takes measurements in terms of microns and can detect changes in the structure of the inside of the eye that are too subtle to be seen with the naked eye. The test itself takes about one minute to complete per eye and is noninvasive. It takes a cross section of the retina, the neural tissue on the inside of the eye, that is interpreted by the Doctor of Optometry. It is especially important in the diagnosis and ongoing monitoring of Glaucoma, Age-Related Macular Degeneration, Diabetic Retinopathy, and many other diseases that affect the health of the eye. The OCT is not required for every patient. Your Doctor of Optometry will recommend this test based on findings in the Comprehensive Eye Exam.