The terms ophthalmoparesis and ophthalmoplegia refer to two similar yet distinct conditions affecting the muscles that control how the eyes move. Ophthalmoparesis refers to a weakening of these eye muscles (the Greek suffix paresis is used medically to refer to weakness), whereas ophthalmoplegia refers to paralysis. Ophthalmoparesis may progresses to ophthalmoplegia, depending on the disease or underlying condition that is causing it. In this article we will discuss both of these conditions, which can have a variety of causes.
Ophthalmoparesis is a weakening of some or all of the extraocular muscles. It is sometimes classified according to which direction of eye movement is affected; for example, a patient who has impaired up-and-down movement of his or her eyes is said to suffer from vertical ophthalmoparesis.
Ophthalmoplegia is complete or near-complete paralysis of some or all of the extraocular muscles.
Symptoms of Ophthalmoparesis and Ophthalmoplegia
Initial symptoms of this condition include:
- Ptosis (drooping eyelid), which may appear before other symptoms are evident.
- Difficulty moving the eyes
- Eye pain and headaches
- Decrease in peripheral vision
In cases in which this condition is congenital (see below), symptoms are likely to begin to appear at some point during childhood or adolescence. As ophthalmoparesis advances and becomes ophthalmoplegia, the affected individual may begin to experience double vision.
Causes of Ophthalmoparesis and Ophthalmoplegia
These conditions are most often caused by certain neurological disorders that interfere with messages sent to the eyes from the brain. The neurological or muscular impairment that leads toophthalmoparesis and ophthalmoplegia can be caused by such things as:
- Bites from certain venomous snakes, including kraits, mambas, and taipans
- Multiple sclerosis
- Parinaud’s Syndrome
- Myasthenia gravis
- Brain tumor
- Physical trauma
These conditions can also be caused by viral infections, or bydiabetes. Other diseases can sometimes mimic theses same symptoms. One example is the proptosis (bulging eyes) caused by Grave’s disease, which can also prevent normal eye movement. Rarely, ophthalmoplegia can also be brought on by a deficiency in vitamin B-1, also known as thiamine. Fortunately, this can be prevented by eating a healthy diet that is rich in thiamine. Meat (especially pork), nuts, and cereal are all good sources of vitamin B-1, as are oatmeal, sunflower seeds, asparagus, kale, potatoes, and oranges. Because dietary sources of thiamine are so abundant, dietary deficiency is one of the least common causes of ophthalmoplegia.
Different Types of Ophthalmoparesis and Ophthalmoplegia
These conditions can sometimes progress to variant disorders, including:
- Internuclear Ophthalmoplegia
People suffering from this condition have specific difficulty looking from side to side. If the left eye is affected, for example, and the affected person attempts to look to the right, the left eye will move only a little or not at all, and the right eye will display the kind of uncontrolled movement normally associated with nystagmus. If the right eye is the affected one, the opposite will occur, the right eye barely moving when the affected person attempts to look to the left.
- Progressive External Ophthalmoplegia (PEO)
This condition is part of a more serious genetic disorder that progresses beyond ocular symptoms. People suffering from PEO will eventually develop weakness in the muscles of the neck, arms, and legs, and they may also experience trouble swallowing.
- Supranuclear Ophthalmoplegia
This disorder reflects a problem with the brain rather than the nervous system. In people with this condition, the brain sends faulty messages to the nerves responsible for controlling eye movement, resulting in a limited range of eye movement (especially vertical movement). It may be caused by a brain disorder known as progressive supranuclear palsy, or by a stroke. In some cases sufferers may also have mild dementia.
Diagnosing and Treating Ophthalmoparesis and Ophthalmoplegia
Diagnosis of this condition will involve a thorough physical examination by an eye specialist, and possibly blood tests and either a CT scan or an MRI. The blood tests will help to rule out thyroid disease as a possible cause. Treatment will depend on what underlying disease is causing the symptoms.