Sub-specialty is a clinical tertiary or above discipline. After completing college education, medical graduates receive systematic and standardized training in the training base recognized by the health department, reach the basic skills required by the specialty, and can basically engage in medical work in a specialty independently. Ophthalmology sub-majors include cornea, cataract, glaucoma, ametropia, ocular muscles, fundus, plastic surgery, ocular trauma, lacrimal passage or ocular surface, pediatric ophthalmology and so on. The full name of ophthalmology is "ophthalmology specialty", which is a discipline that studies diseases related to the visual system, including the eyeball and its related tissues. Ophthalmology generally studies vitreous and retinal diseases, optometry, glaucoma and optic neuropathy, cataracts and other ophthalmic diseases.

Common ophthalmic diseases include: central serous retinopathy, dry eye, sympathetic ophthalmia, night blindness, blindness, amblyopia, astigmatism, trachoma, cataract, diabetic retinopathy, conjunctivitis, presbyopia, color blindness, iris heterochromia, retinitis pigmentosa, central retinal artery occlusion, retinal detachment, myopia, hyperopia, needle eye, snow blindness and visual impairment.