The diseases of the posterior segment of the eye are those that affect the retina, choroid, and optic nerve. Some examples include retinopathies (diabetic, most prominently), optic neuritis, macular degeneration, intravitreous hemorrhages, and retinal detachment. For optimal comprehension, the student must be familiarized with the anatomical structure of the posterior segment and the layers of the eye, hydrodynamics of vitreous fluid, irrigation of the retina, retinal physiology, and how to visualize the ocular fundus. In clinical practice, posterior segment disease, especially those affecting the retina, can cause severe disability due to the abrupt loss of visual acuity. The clinician must also be aware that retinal health is an indirect indicator of cardiac health.