Neuro-ophthalmology Visual Disorders
The human eye is an organ that reacts to light and allows us to see. It is a part of the sensory nervous system. The front includes the iris (shaded part), the cornea (a clear bulge over the iris), the pupil (circular black opening in the iris that allows light to come in), sclera (white part of the eye) and conjunctiva (a lean layer of sensitive tissue that covers the front of the eye, with the exception of the cornea). Optic nerves are located in the back of the eye and play a vital role in the ability to see. It is also called the second cranial nerve or cranial nerve II. The primary role of the optic nerve is to transfer visual information from the retina to the vision centers of the brain through electrical impulses. There are plenty of Neuro-ophthalmology disorders and problems that are related to nervous system and complex systemic diseases that have manifestations in the visual system. Disorders of the optic nerve, eye-ball movement, pupil abnormalities and central nervous system can cause vision disturbances or loss of vision.
Optic Nerve Disorder
- Compression: One of the major disorders in optic nerve includes its compression. This occurs when the brain tissue is compressed by any space occupying lesion including tumors, brain abscess or swelling of the brain. The increased pressure in the brain causes swelling of the optic nerve, which affects the overall performance and function of the visual system. Long-term compression of the nerves may lead to severe damage and nerve death, also known as optic atrophy. Leading symptoms of the optic nerve compression is a gradual decline in vision and vision loss. Surgery or medical treatment is required to correct optic nerve compression.
- Eye movement: This type of disorder is common in children, where both eyes are unable to focus in the same direction, or it may present as repetitive movements of the eye. Irregular movements and abnormal appearance of the eye are an important symptom to look for in the initial stages. Different kinds of treatment including prescription glasses and/or surgery are required depending on the cause.
- Glaucoma: This is a major disease affecting vision. In severe conditions, it may cause damage to the optic nerve of the eye and can lead to
blindness. Glaucoma can manifest as increased intraocular pressure. It may occur in the presence of normal eye pressure or may be caused by poor regulation of blood flow to the optic nerve. Most people with open-angle glaucoma feel fine and do not notice a change in their vision at first because the initial loss of vision is the peripheral vision, and the visual acuity or sharpness of vision is maintained until late in the disease. It is characterized by a specific pattern of progressive damage to the optic nerve that generally begins with a subtle loss of side vision. If glaucoma is not diagnosed and treated, it may progress to loss of vision and blindness.
- Raised pressure in the Brain: Intracranial hypertension is a condition caused due to high pressure within the spaces that surround the brain and the spinal cord. These spaces are filled with cerebrospinal fluid, which cushion the brain from mechanical injury, carry away waste and provide nourishment. The most common symptoms of intracranial hypertension are headaches and visual loss, including blind spots, poor peripheral vision, double vision, or short temporary episodes of blindness. Some patients may experience permanent vision loss. Other common symptoms include ringing in the ears as well as neck and shoulder pain.
- Optic Neuritis or Inflammation of the optic nerve: Optic Neuritis leads to swollen optic nerves caused by damage to the myelin sheath surrounding the nerve, which is vital for its function. Vision symptoms may include blurring and blind spots. You may also notice distorted vision, reduced color vision and pain when you move your eyes. These types of symptoms may precede vision loss due to optic neuritis. It usually occurs in adults younger than 45 and affects more women than men. This condition is common in people who have multiple sclerosis, which occurs when the immune system attacks and destroys protective nerve coverings. Besides affecting eyesight, related nerve damage in multiple sclerosis can also lead to loss of mobility and sensory functions, along with other debilitating conditions.
- Ischemic optic neuropathy: A sudden loss of vision in one or both eyes due to an interruption or lack of blood supply to the front of the optic nerve, also known as the optic nerve head. When blood flow to the optic nerve is reduced or blocked, the nerve does not get enough oxygen or nutrition. The optic nerve then stops working properly and eventually dies. Because a damaged optic nerve cannot be fixed, any vision loss from Ischemic optic neuropathy is usually permanent. If blood flow to your optic nerve is reduced, your vision will darken for a few seconds or minutes and will then return to normal. This condition is called a transient ischemic attack (TIA). This type of attack can happen before Ischemic optic neuropathy begins. If you have TIA symptoms, make an appointment with an eye doctor promptly. Finding and treating the problem as soon as possible can help prevent further vision loss from Ischemic optic neuropathy.
For treatment options of neuro-ophthalmology, contact your eye doctor or neurologist.