What is the cause of my vision loss and visual field defects? There are many causes of vision loss and visual field defects, so for the sake of understanding, I will start with the physiological anatomy and pathophysiology of vision formation. The formation of vision is dependent on the visual conduction path: when there is an object in front of the eyes, the object reflected light through the pupils of both eyes, lens, vitreous irradiation on the retina in the fundus, the retina has two types of cells (cone cells and optic rod cells) for photoreceptor cells, it will feel the stimulus information through two levels of nerve cells (bipolar cells, ganglion cells) to the optic nerve formed by the collection of nerve discs in the fundus, the optic nerve through the The optic nerve crosses the optic canal into the skull, and the bilateral optic nerves are semi-crossed medially to form the optic tract, which enters the brain and finally lands in the occipital lobe (visual center) so that we can see objects. The visual pathway is more complex, as the optic nerve fibers at the optic crossings are partially crossed, where the nerve fibers from the nasal half of both eyes are crossed and the nerve fibers from the temporal half are not crossed. The optic tract bypasses the cerebral peduncle and passes through the lateral geniculate body (lateral geniculate cells) to the intracerebral optic radiation (via the posterior peduncle of the internal capsule) before reaching the cerebral cortex on both sides of the occipital talar sulcus. This is not described here. What is the visual field? The maximum space that the eye can see when the eye is fixed and looking forward. The visual field is divided into a temporal half and a nasal half depending on the location. Because the lens resembles a biconvex lens, the object image of the temporal half of the visual field of one eye is projected onto the nasal half of the retina of the ipsilateral eye, and the object image of the nasal half of the visual field is projected onto the temporal half of the retina of the ipsilateral eye. What is the cause of vision loss and visual field defects? It is related to each link of the conduction path of vision formation. 1. Eye disorders . The eye functions as a camera in the vision formation process, forming images in the fundus of the eye before they are uploaded to the brain via the nerves. Disorders of the eye lead to impaired imaging and insufficient information to the brain, resulting in blurred vision, decreased visual acuity, and visual field defects. (1) Trauma to the eye Damage to the refractive system of the eye resulting in loss of vision. (2) Sudden vision loss due to normal eye appearance: central retinal artery obstruction, acute retrobulbar optic neuritis, optic neuromyelitis optica, multiple sclerosis, central retinal vein obstruction, peripapillary retinal veinitis and diabetes, fundus hemorrhage, retinal detachment, ischemic optic papillopathy, optic papillary retinitis, acute methanol, quinine type poisoning, etc. (3) Causes of ocular congestion or infection with rapid vision loss: acute closed glaucoma, acute iridocyclitis, keratitis, corneal ulcer, endophthalmitis, total ocular abscessitis, severe mechanical ocular trauma, thermal burns, chemical burns, etc. (4) Causes of gradual vision loss in eyes without congestion: myopia, presbyopia, amblyopia, cataract, corneal degeneration, simple glaucoma, vitreous opacity, retinal chorioretinitis, optic neuropathy, optic nerve atrophy, retinitis pigmentosa, early retinoblastoma, early choroidal melanoma, etc. (5) Causes of ocular congestion with chronic vision loss: keratitis, corneal ulcer, slow closing glaucoma, ocular trauma, chronic iritis, fungal keratitis, endophthalmitis, late conjunctival and corneal alkali burns, etc. 2, optic nerve, optic cross damage. (1) Optic nerve compression There is no problem with the optic nerve itself, but rather vision loss and visual field defects due to tumor or aneurysm compression stimulating the optic nerve and optic cross. Injury to one side of the optic nerve can cause total blindness in that eye. Injury to the middle part of the optic cross, causing temporal partially blindness of the visual field in both eyes. Injury to one side of the optic tract, resulting in simultaneous blindness on one side of the visual field of both eyes. This is a common cause, such as pituitary aneurysm, craniopharyngioma, posterior communicating artery aneurysm, often appear visual field impairment. (2) Craniocerebral trauma combined with optic nerve damage. (3) Primary optic neuritis, optic nerve glioma, less common. Damage to one optic tract, lateral geniculate, optic radiation or visual center causes bilateral visual field ipsilateral hemianopia, i.e., nasal hemianopia of the affected visual field and temporal hemianopia of the contralateral visual field. What should I do about vision loss and visual field defects? The cause of vision loss, visual field loss friends, please do not rush, from the onset of the disease, the eye itself is more common, so first to the hospital ophthalmology to see to early treatment. Especially for teenagers, refractive error is the most common cause of vision loss, which is myopia. Please love your eyes, protect your eyes to avoid myopia, if you have formed myopia, you can only press the glass for the window of your heart eyes – wearing glasses. When the ophthalmology can not find the problem, we should consider neurosurgery, in neurosurgery examination most of the time to carry out cranial CT or MRI examination, the main purpose is to check whether there are intracranial lesions, to further clarify the diagnosis.