The eye is one of the most important and sophisticated senses of the human body. Its main function is to provide the human body with visual senses, such as light and darkness, size and shape of objects, color, movement and orientation. With its existence, we have a colorful world and various human activities; human learning and knowledge cannot be obtained without the eyes, and it is everyone’s good wish to have a pair of bright and beautiful eyes. According to common sense, people know that when there is a lesion in the eye, they will go to the ophthalmology department, but they do not know that there are many eye lesions caused by neurological problems. If you have the following knowledge, you can quickly determine which type of disease you are suffering from and quickly find the relevant department to avoid detours. The eye is a very sophisticated visual organ with a structure similar to a “camera”. There are six muscles outside the eye (internal and external rectus, superior and inferior rectus, superior and inferior oblique muscles) that provide adjustment for flexible rotation, and several nerves involved in the formation, processing and transmission of visual images in the eye. The more famous nerves are 1) optic nerve: dedicated to transmitting image information sensed by the retina to the center; 2) sympathetic nerve: used to control the opening of the pupil; 3) parasympathetic nerve: controls the narrowing of the pupil; 4) motoneurotic, trochlear, and abducens nerves: mainly control the activity of six muscles outside the eye and the lifting of the eyelid. In addition the blood to the eye is obtained from the ophthalmic artery which is a branch of the internal carotid artery. It is the division of labor of some such indispensable neuromuscular vessels that provides an important guarantee for the function of the eye. Neurology-related eye lesions are commonly found in three categories: extraocular muscles, nerves, and blood vessels, which are described as follows: 1. Extraocular muscle-related lesions: such as upper and lower rectus muscles, internal and external rectus muscles, and upper and lower oblique muscles paralysis, which mainly cause diplopia, double vision, and different positions of the eyeballs. It is common in secondary diabetes, hyperthyroidism, myotonic dystrophy, myasthenia gravis, etc. Although the main problem appears in the eye muscle system, it actually reflects the occurrence of one kind of lesion in the whole body, and the symptoms will gradually aggravate if not treated in time. 2, nerve-related lesions: such as the motoneurotic nerve, the talocrural nerve, the abducens nerve, the sympathetic nerve and the parasympathetic nerve, paralysis of these nerves can cause eyelid ptosis and pupil dilation or narrowing, in addition to the performance of similar eye muscle paralysis. Common diseases that cause these nerve palsy include cerebrovascular blockages in the midbrain, aneurysms, multiple sclerosis, infectious inflammation of the skull base and cavernous sinuses, and diabetes mellitus. In general, paralysis of the nerve in the articulating nerve is often accompanied by eyelid ptosis; nerve paralysis caused by inflammation of the cavernous sinus is also accompanied by severe headaches, which we call Tolasa-Hunt syndrome; damage to the optic nerve, an important pathway responsible for transmitting external image signals to the brain center, can cause vision loss and visual field defects, and multiple sclerosis often causes damage to the optic nerve. In addition, nerve damage can also affect pupil size, such as dilated pupils in atropine poisoning, arteriolar nerve compression, and brain herniation; and organophosphorus pesticide poisoning, morphine poisoning, and central syphilis can cause pupil size to become smaller. There is also a rare phenomenon in young women that manifests as tonic pupil dilation without any discomfort (unilateral or bilateral), a blunted light reflex, a normal conditioning reflex, and a concomitant loss of Achilles tendon reflex, called Adie’s syndrome, the clinical significance of which is still unclear. 3. Vascular-related lesions: The human internal carotid artery enters the skull and divides into an ophthalmic artery, which is responsible for supplying blood and nutrients to the eye. If the blood vessel itself is atherosclerotic, occluded or ruptured, it can cause blood circulation disorders in the eye and produce lesions, among which the retina is greatly affected, causing vision loss and visual field defects. The sudden onset of vision or visual field changes should be immediately alerted and promptly treated to avoid aggravation of the damage and permanent blindness. In addition, there are some more rare eye disorders associated with the extrapyramidal nervous system, such as hepatomegaly caused by abnormal copper metabolism, which often forms a ring of yellow-green copper deposits called the “K-F ring” at the edge of the iris of the eye. Some people have involuntary eyelid twitching, called blepharospasm, and sometimes facial muscle twitching, called facial myasthenia gravis, which can be easily confused with myasthenia gravis or facial nerve palsy. In addition, some patients have involuntary up and down or left and right eye movements, which is medically called “nystagmus” and is usually associated with cerebellar lesions. In summary, the connection between the eye and neurological diseases is really close and complex. Therefore, if a patient has eye discomfort or vision changes, when he or she goes to the ophthalmology department, he or she may also want to register for a neurology appointment and ask the neurologist to take a closer look.