1.Sudden visual impairment refers to a rapid loss of vision or blindness in one or both eyes. It is seen in central retinal vascular obstruction, intraocular hemorrhage, acute uveitis, retinal detachment, acute optic neuritis, methanol or quinine poisoning, acute angle-closure glaucoma, severe ocular trauma and craniocerebral trauma, pseudo-blindness, toxic amblyopia, and uremia, eclampsia, hysteria, etc. 2. Transient or paroxysmal visual impairment refers to transient or paroxysmal blurring of vision in one or both eyes. It is seen in the prodromal phase of acute angle-closure glaucoma, early stage of optic papilloedema, cardiovascular spasm and postural hypotension in the retina, high intracranial pressure, transient cerebral ischemia and mental stimulation, etc. 3, progressive visual impairment vision gradually decreases, the course of the disease is generally long. It is seen in inflammation of cornea, sclera, orbit, pterygium, corneal vascular opacity, corneal degeneration, cataract, primary open angle glaucoma, retinal choroidopathy, chronic retrobulbar optic neuritis, optic nerve atrophy, and chronic poisoning by lead, tobacco, alcohol, methanol, etc. 4, congenital visual impairment refers to the blurred vision caused by congenital factors. It is seen in conical cornea, flat cornea, congenital corneal leukoplakia, small eye, large eye, no eye and cryptophthalmos, pupillary residual membrane, no iris, multiple pupils, primary retinitis pigmentosa, retinal schwannoma, white dot retinal degeneration, crystalline retinal degeneration, macular degeneration, microphthalmia, retinoblastoma, optic nerve defect, crystal anomaly and clouding, congenital glaucoma, albinism, and Marfan syndrome, etc. 5.Visual distortion refers to straight as curved, round as curved, large as small or small as large. It is seen in central retinopathy, chorioretinitis, retinal detachment, glaucoma, cataract, etc. Large vision is seen in hysteria, regulatory spasm, retinal scar contraction; small vision is seen in regulatory weakness or paralysis, refractive aberration, unequal pupils, macular edema, hysteria, early retinal detachment, etc. 6, flashing sensation flashing or lightning-like sensation in front of the eyes. See in iris tremor, retinal detachment precursor, retinal chorioretinitis, vitreous proliferation traction, posterior vitreous detachment, advanced optic nerve atrophy, eye contusion at that time, before syncope. 7.Phantom vision appears in front of the eyes with illusory flashes, bright spots, and color. It can be seen in occipital or parieto-occipital lobe lesions of the brain. Various illusory images appear in front of the eyes, which can be seen in mental disorders such as hysteria, temporal lobe or parietal temporal lesions. 8. Diplopia or polyopia Diplopia is when one object is seen as two. Monocular diplopia is seen in crystal dislocation, double pupils, etc.; binocular diplopia is seen in extraocular muscle paralysis, eye displacement due to traction or pressure, movement disorders, etc.; hyperopia is seen in one object as more than one, seen in incipient cataract, corneal clouding, irregular astigmatism, multiple pupils, hysteria, etc. 9, day blindness in the dark is still clear, but the light bright place but blurred vision. See in total color blindness, corneal or crystal central clouding, axial optic neuritis, macular disorders, etc. 10, night blindness daytime vision is still clear, into the night or in the dark vision blurred significantly aggravated. It is seen in vitamin A deficiency, retinitis pigmentosa, white dot retinitis, diffuse chorioretinitis, optic nerve atrophy, etc. 11, congenital color vision disorder means abnormal color vision after birth, not secondary to or accompanied by other eye diseases. Commonly seen in color blindness or color weakness, also seen in hemophilia, ocular regression syndrome, etc. 12.Acquired color vision disorder refers to those with color vision abnormalities secondary to or associated with other eye diseases. Red-green color vision disorder is seen in optic neuritis, optic nerve atrophy, macular degeneration; blue color vision disorder is seen in choroidal defects, retinal choroiditis, retinal detachment, etc. 13, rainbow vision to see white lights around the sky like a rainbow. Seen in corneal edema, initial nuclear cataract, glaucoma, vitreous clouding, glasses lenses with water vapor.