The human eye is like a high-definition camera, and the retina is the light-sensitive film behind the high-definition camera. The retina’s function is similar to that of a light-sensitive film, and is critical to imaging. Once the retina has a problem, the human eye is like a camera without a negative, completely losing its imaging function. When patients visit the doctor, often mentioned with the doctor “I have macula”, this reference in the end is right or wrong, read the following description, we may have a clear picture in mind. What exactly is the retina? The retina is the visual nerve endings tissue extending outward from the brain, located in the inner layer of the eyeball wall. The important landmarks on it are the optic disk and the macula. The retina consists of the pigment epithelium and the retinal sensory layer. The pigment epithelium is closely connected to the choroid, and once detached, it can affect the function of the human eye’s vision Functions of the retina The retina serves two functions: to capture light from the outside world, and to process light-induced stimuli. The realization of these functions depends on the retina’s thin but complex ten-layer structure. Photoreceptors – cone and rod cells – capture photons of light and their nerve impulses travel along the bipolar cells to the ganglion cells and finally to the optic disk, where they pass through the optic nerve and optic nerve crossings to the brain for processing. Two important structures on the retina 1. Optic disk: It is a light red disk-like structure with a clear boundary, which is the part where the optic nerve passes out of the eyeball. There are no photoreceptor cells in the optic disk, so there is no photoreceptor effect, which is also the reason for the existence of the human physiological blind spot. 2, macula: macula is an important structure of the retina, located in the posterior pole of the eye, mainly associated with fine vision and color vision and other visual functions. Once macular lesions occur, vision loss, dark shadows in front of the eyes or distorted vision often occur. Retina Related Diseases Primary lesions of the retina include retinal vasculopathy, macular degeneration, retinal detachment, retinal degeneration, and retinal tumors (e.g. retinoblastoma), etc. In addition to these primary changes, there are also retinal tumors (e.g. retinoblastoma). In addition to these primary changes, there are also changes secondary to systemic diseases. Because the blood vessels of the retina are the only small blood vessels that can be seen directly by the human body, the changes in the fundus of the eye are often used to determine the changes in systemic diseases, such as hypertension, arteriosclerosis, diabetes mellitus, hyperthyroidism, and so on.