The eyes are the windows to the soul, and when that window is dusty, you can’t get a good feel for this wonderful world. When vision loss makes you see things blurry, the first reaction of many people is whether there is something wrong with their eyes. It is true that various diseases of the eyes are the most common causes of vision loss. However, in terms of the anatomical pathway of vision, the eye is only one part of the pathway, and a problem in any part of the pathway can cause vision loss and blurred vision. The visual conduction pathway simply means that after the light reaches the retina of the eye, the nerve impulses caused by it pass through the optic nerve disk of the eye, the optic nerve passes through the optic nerve canal into the skull, and in the saddle area, it passes through the optic nerve crossings and continues to the optic bundles, and then bypasses the cerebral peduncle to reach the lateral geniculate body, and then forms the optic radiations, and passes through the posterior limb of the internal capsule of basal ganglia, and forms the optic radiations to reach the visual centers of the occipital lobe. Any lesion in this passage, from the section of the optic nerve that enters the skull to the visual center in the occipital lobe, may cause vision loss. Brain tumors are most commonly caused by compression of the optic nerve or visual crossover by tumors in the saddle region. Pituitary tumors, craniopharyngiomas, meningiomas, and gliomas that are common in this area can compress these structures causing similar symptoms of vision loss, and in addition to vision loss, they can also cause visual field defects, which means that the range of vision of the eye becomes smaller. The optic radiation and occipital visual center can also be invaded by tumors causing vision loss, but generally it is more common to cause visual field defects, and only when both sides are affected at the same time is it easy to cause vision loss or even blindness. Ms. Lang, 23 years old, has suffered from significant vision loss in the past few months, especially in her left eye, which is almost blind, and in her right eye, her vision is only 0.3, but no problem was found in the ophthalmology department. Fortunately, Ms. Lang met an experienced ophthalmologist who suggested her to do a brain MRI, which revealed a pituitary tumor in her brain. Neuro-Oncology Surgery used an endoscope to remove the pituitary tumor through an invisible incision in the nasal cavity without any problems, and as soon as the surgery was over, Lang felt like she could see things brighter all of a sudden. In addition to brain tumors near the visual conduction pathway that tend to cause vision loss, in fact, tumors in any part of the brain that are large enough to cause an increase in intracranial pressure, which is transmitted to and affects the optic nerve, can cause vision loss. Moreover, in addition to affecting visual pathways, brain tumors may also cause blurred vision by affecting eye movement. The activity of the eyeball requires the coordinated movement of extraocular muscles, and if the nerves that innervate the extraocular muscles, such as the buccal nerve, the motor nerve, and the abducens nerve, are affected by the tumor, the activity of the eyeball becomes uncoordinated, and the blurring of vision occurs as a result of double shadows. Therefore, if there is a significant loss of vision, do not only think of eye lesions, but also need to be alert to whether it is caused by brain tumors.