Ophthalmology and neurology cross paths in various ways since the eye as an organ of vision is connected to the brain via neuromuscular structures in the ocular cavity as well as the entire visual pathway, i.e., the central and autonomic nervous system. Therefore, a number of neurological disorders resulting from damage or irritation of these neuromuscular structures in the eye cavity can – in addition to clinical neurological manifestations and symptoms – also result in ophthalmic manifestations of a disease.
• Cerebrovascular disorders
The most common ones are cerebrovascular disorders that can present as visual impairment depending on the type of loss in the visual field, short-term transient blurred vision, vision loss in one or both eyes, transient double vision, visual hallucinations, optical agnosia, disorders affecting eyeball movement, all of which may be caused by changes in blood vessels.
Headaches are one of the most common neurological symptoms, they can be caused by trauma, vascular disorders, inflammatory disorders and tumours of the central nervous system. The most common type of headache that is very often associated with visual manifestations is migraine (in the form of distorted images, flashes in the visual field, sectoral loss in the visual field, complete transient loss of vision or damage affecting eye movement and periocular pain).
Brain tumours (benign or malignant), brain lymphomas and tumour-related processes of the pituitary gland or the optic nerve itself can also cause visual disturbances depending on where this process is localised (visual field loss, eyeball protrusion, papilledema).
• Inflammatory and other disorders
Inflammatory disorders of the brain – nerves or muscles, metabolic disorders, endocrine disorders, autoimmune demyelinating disorders, degenerative disorders of the central nervous system, disorders caused by nutrient deficiencies or exposure to toxins – may manifest as photophobia, blurred vision, impaired vision or complete loss of vision, impaired eyeball movement, impaired colour perception, anisocoria (unequal pupil size) or eyeball protrusion.
• Neuromuscular disorders
Neuromuscular disorders, the most significant of which is myasthenia gravis, can present as ophthalmic manifestations (double vision, drooping eyelids).
Traumatic damage to the brain and meninges – ranging from concussions to subdural and epidural bleeding or brain contusion and cerebral oedema – can cause ocular manifestations (impaired vision, narrowing of the visual field, unequal pupil size).
Some types of epilepsy may be associated with ocular manifestations, e.g. visual impairment as a precursor to epileptic seizures; photostimulation may affect the propagation of an epileptic seizure, while post-convulsive seizures may be a transient or permanent side effect.
In case of certain substances associated with impaired consciousness or other neurological disorders, changes in the pupils (miosis, mydriasis) or various visual disturbances may be pronounced.
• Other disorders of the nervous system
A very common symptom is blepharospasm – it is manifested by involuntary twitches or movements or spasms of the muscles of the upper or sometimes lower eyelid. Minor eyelid twitching is often harmless and associated with daily activities such as fatigue, stress, excessive consumption of caffeine, alcohol or smoking, as well as sensitivity to light. This is sometimes associated with taking certain medications or with disorders of the central nervous system, which includes Parkinson’s disease, multiple sclerosis, Bell’s palsy, Tourette’s syndrome, dystonia.