Ophthalmology focuses on diseases of the eye, including various eye diseases associated with systemic diseases. First of all, the eye is an organ of vision and consists of three parts: the eyeball, the optic pathway and the appendages. The eye is composed of the wall of the eye and the contents of the eye. The wall of the eye is divided into three layers, the outer layer is the fibrous membrane, the middle layer is the uveal membrane, and the inner layer is the retina, so the associated diseases, including corneal, scleral, uveal, and retinal lesions; the contents of the eye include the atrium, lens, and vitreous. If the anterior chamber bleeds, the lens is cloudy to form a cataract, or the vitreous is cloudy, you need to go to the hospital ophthalmology department in time. The appendages of the eye include the eyelids, conjunctiva, lacrimal apparatus, extraocular muscles, orbit, etc. These are also the subject of an ophthalmology visit. Second, the eye is also a refractive system. The total refractive power of the normal eye is approximately 58.64 D. Therefore, refractive related diseases, such as myopia, astigmatism, hyperopia and other refractive errors, can also be seen at the optometric center of the local hospital. In addition, medications or poisoning that cause visual impairment, or systemic diseases with various complications in the eye, require consultation and examination in the ophthalmology department. In particular, patients with hypertension, diabetes, kidney disease and other systemic diseases cause retinopathy. It is important to go to the hospital ophthalmology department for timely treatment.