Ophthalmoplegia is a condition that affects the muscles responsible for eye movement, causing weakness or complete paralysis that can impact daily activities and quality of life in unexpected ways.
When you think about how your eyes move throughout the day, it’s easy to take for granted the complex coordination between muscles and nerves that allows you to look around, read, drive, and interact with the world. Ophthalmoplegia disrupts this coordination, causing the muscles that control eye movement to become weak or paralyzed. This condition can affect one eye or both, and it can involve the external muscles that move the eyeball or the internal muscles that control pupil size and focusing.
The term ophthalmoplegia comes from medical terminology meaning paralysis or weakness of the eye muscles. It can affect any of the six external eye muscles that hold the eye in place and control its movement, or the three internal eye muscles that control pupil size and help the eye focus. The condition generally occurs because something disrupts the messages sent from the brain to the eyes, interfering with the normal communication pathways that make smooth, coordinated eye movements possible.[1][2]
Types of Ophthalmoplegia
There are two main types of ophthalmoplegia that affect people in different ways. Chronic progressive external ophthalmoplegia typically appears in adults between the ages of 18 and 40 years. This condition usually begins with drooping eyelids, a symptom called ptosis, which can affect one or both eyelids. As the condition progresses, people develop difficulty controlling the muscles that coordinate the eyes. The word “progressive” indicates that symptoms tend to worsen slowly over time, often over months to years.[1][4]
Internuclear ophthalmoplegia is caused by nerve damage to the nerve fibers that coordinate lateral eye movement, particularly affecting a pathway called the medial longitudinal fasciculus. This nerve pathway is responsible for transmitting information vital for the coordination of different eye movements. When this pathway is damaged, one eye cannot turn inward toward the nose when you try to look to the opposite side, while the other eye may make involuntary back-and-forth movements. This leads to double vision and difficulty coordinating both eyes together.[1][3][6]
How Common Is Ophthalmoplegia
Chronic progressive external ophthalmoplegia is an uncommon condition, affecting approximately 10 per 100,000 people. This means that in countries with large populations, only a few thousand new cases are diagnosed each year. The condition typically begins when people are in their twenties to thirties, though this timing can vary depending on the specific genetic factors involved.[19]
Internuclear ophthalmoplegia has different patterns depending on what causes it. About one-third of cases are caused by strokes and are commonly unilateral, meaning they affect only one eye. These cases are typically seen in older individuals. Another third of cases result from demyelinating disorders like multiple sclerosis, and these are mostly bilateral, affecting both eyes. These cases are more commonly seen in young adults and adolescents. Some studies have shown that internuclear ophthalmoplegia occurs in about 23 percent of patients with multiple sclerosis. The incidence of internuclear ophthalmoplegia in males and females is almost equal.[6]
Internuclear ophthalmoplegia is extremely rare in the pediatric population. When it does occur in children, tumors such as medulloblastoma and pontine gliomas are important causes, in addition to trauma, vasculitis, infarction, and hemorrhage.[6]
What Causes Ophthalmoplegia
Ophthalmoplegia can be congenital, meaning present at birth, or it can develop later in life. The condition is generally caused by disruption of the messages sent from the brain to the eyes. Understanding what causes this disruption helps explain why the condition affects different people in different ways.[1]
Internuclear ophthalmoplegia is often caused by multiple sclerosis, trauma, or infarction, which is tissue death resulting from lack of blood supply. Some people develop internuclear ophthalmoplegia after experiencing a stroke that damages their brainstem. The brainstem is the stalk-like part of the brain that connects the brain to the spinal cord and sits toward the bottom of the brain as part of the central nervous system.[1][3]
External ophthalmoplegia is usually caused by muscle disorders or mitochondrial diseases. Mitochondria are the energy production centers of cells, so when there is an issue with a cell’s mitochondrion, that cell doesn’t have sufficient energy to function correctly. Conditions such as Graves’ disease or Kearns-Sayre syndrome can trigger this type of ophthalmoplegia. Progressive external ophthalmoplegia is caused by genetic defects that result in the deletion of large segments of mitochondrial DNA in muscle cells.[1][4]
Other common causes include migraines, thyroid disease, stroke, brain injury, brain tumors, and infections. Various infections can lead to ophthalmoplegia, particularly when they cause encephalitis, which is inflammation of the brain. Infections like Lyme disease, HIV, and herpes zoster (the virus that causes chickenpox and shingles) have been associated with ophthalmoplegia.[1][3]
Risk Factors for Developing Ophthalmoplegia
Certain groups of people face higher risks of developing ophthalmoplegia than others. Ophthalmoplegia is slightly more likely to occur in people with diabetes. Men with diabetes who are over the age of 45 and have had type 2 diabetes for more than 10 years were recently identified as a higher risk category for developing ophthalmoplegia. This connection between diabetes and eye muscle problems highlights the importance of managing blood sugar levels and attending regular medical checkups.[1][10]
People who have conditions that affect their muscle control face elevated risks. Multiple sclerosis, Graves’ disease, and other autoimmune conditions increase the likelihood of developing ophthalmoplegia. Autoimmune diseases including lupus and Sjögren’s syndrome have been linked to internuclear ophthalmoplegia. These conditions can damage the nerve pathways that coordinate eye movements.[1][3]
In general, there are no lifestyle choice factors that contribute to being at risk for ophthalmoplegia. However, keeping a healthy vascular system by maintaining a balanced lifestyle may lessen risk factors. This includes managing blood pressure, controlling diabetes if present, avoiding smoking, and following medical advice for any existing health conditions.[1]
For progressive external ophthalmoplegia specifically, genetic factors play the primary role. Since this is an inherited mitochondrial disease, there is often a family history of the condition. If family members have experienced similar symptoms, this increases the likelihood that a genetic form of ophthalmoplegia may be present.[4]
Symptoms of Ophthalmoplegia
People affected by ophthalmoplegia experience a range of visual and physical symptoms that can significantly impact daily life. One of the most noticeable symptoms is double vision, also called diplopia. This occurs when the eyes cannot work together properly, causing a person to see two of the same image, either side by side or one above the other. Some people may also experience blurred vision, which can result from a combination of uncoordinated eye motion and loss of focus control.[1][3]
Many people with ophthalmoplegia experience an inability to position their eyes in sync. When trying to look in different directions, the eyes may not move together as they should. Some people have difficulty moving both eyes in every direction, and to see what they want to look at, they may need to turn their entire head rather than just moving their eyes. This limitation can affect activities like reading, driving, and following conversations with multiple people.[1]
Drooping of the eyelids, or ptosis, is particularly common in chronic progressive external ophthalmoplegia. This often begins as the earliest symptom, with one or both eyelids gradually becoming heavier and more difficult to keep open. As ptosis worsens, affected individuals may use their forehead muscles to try to lift the eyelids, or they may lift up their chin to see better. This drooping can narrow peripheral vision and make daily tasks more challenging.[1][4]
The most obvious symptom of internuclear ophthalmoplegia is one eye not moving when you look to the side. When you look to one side, the affected eye stays looking straight ahead or doesn’t move all the way in the direction you’re looking. For example, if you look to the right, your left eye won’t move with your gaze, or if you look to the left, your right eye won’t move all the way past center. The unaffected eye may also make involuntary, repetitive fluttering movements. Other symptoms include dizziness and worsened vision.[3][9]
If ophthalmoplegia is associated with a systemic disorder affecting other parts of the body, additional symptoms may develop. These can include difficulty swallowing, general muscle weakness in the neck, arms, or legs, and problems with balance or coordination. Some people may experience weakness that becomes especially noticeable during exercise, a condition called exercise intolerance.[1][4]
Prevention of Ophthalmoplegia
Because ophthalmoplegia often results from genetic factors or underlying medical conditions, there are limited ways to prevent the condition entirely. However, certain lifestyle measures and health management strategies can reduce the risk of developing some forms of ophthalmoplegia or experiencing complications from existing conditions.
Maintaining a healthy vascular system through balanced lifestyle choices can help reduce risks associated with stroke-related ophthalmoplegia. This includes managing blood pressure through regular monitoring, maintaining healthy cholesterol levels, avoiding smoking, limiting alcohol consumption, eating a balanced diet, and engaging in regular physical activity. These measures support overall brain and nerve health, which can reduce the risk of strokes and other conditions that damage the pathways controlling eye movements.[1]
For people with diabetes, careful management of blood sugar levels is particularly important. Since diabetes, especially when poorly controlled over many years, increases the risk of ophthalmoplegia, following medical advice regarding diet, medication, and blood sugar monitoring can help reduce this risk. Regular medical checkups allow healthcare providers to identify and address problems before they progress.[1][10]
People with multiple sclerosis or other autoimmune conditions should work closely with their healthcare providers to manage these underlying conditions. While this doesn’t prevent ophthalmoplegia entirely, proper disease management may reduce the risk of complications affecting eye movements. Following treatment plans and attending regular medical appointments helps monitor for early signs of problems.[6]
For families with a history of progressive external ophthalmoplegia or other mitochondrial diseases, genetic counseling can provide valuable information. While genetic testing cannot always predict outcomes because these disorders result from complex genetic errors and can have diverse presentations, counseling can help families understand their risks and make informed decisions about family planning and monitoring.[13]
How Ophthalmoplegia Affects the Body
Understanding the pathophysiology of ophthalmoplegia means looking at how normal body functions change when the condition develops. The eyes are controlled by a sophisticated system of muscles and nerves working together. Six external muscles attached to each eye control its movement in different directions, while internal muscles control the pupil’s size and the lens’s focusing ability.
In internuclear ophthalmoplegia, damage occurs to the medial longitudinal fasciculus, which is a paired white matter tract passing close to the midline through the brainstem. This tract lies ventral to the cerebral aqueduct in the midbrain and the fourth ventricle in the pons and medulla. It serves as the final common pathway for different types of conjugate eye movements like saccades (rapid eye movements), smooth pursuit (tracking moving objects), vestibulocochlear reflex, and forms communication between all the ocular motor nuclei. When this pathway is damaged, the brain cannot properly coordinate the muscles that move the eyes together.[6]
In progressive external ophthalmoplegia, the problem lies at the cellular level within the muscles themselves. Defects in mitochondrial DNA lead to problems with energy production in muscle cells. Because mitochondria are the powerhouses of cells, converting oxygen and nutrients into energy, when they malfunction, the affected cells cannot work properly. The eye muscles, which require constant energy to maintain position and create smooth movements, become progressively weaker over time.[4]
When muscle cells from affected individuals are examined under a microscope after special staining, they usually appear abnormal. These cells contain an excess of mitochondria and are known as ragged-red fibers because of their appearance under the microscope. The size of deleted regions in mitochondrial DNA can range from 2,000 to 10,000 DNA building blocks called nucleotides.[4]
The condition typically affects organs and systems that use high oxidative phosphorylation activity. This explains why ophthalmoplegia sometimes occurs alongside problems in other parts of the body. The brain and neurological pathways, the heart, the muscles, and the lungs all depend heavily on efficient energy production. When mitochondrial function is impaired, these systems can develop symptoms ranging from muscle weakness to more serious complications affecting multiple organs.[13]
Ophthalmoplegia usually involves the third (oculomotor), fourth (trochlear), or sixth (abducens) cranial nerves. These nerves carry signals from the brain to the eye muscles. In oculomotor paralysis, the muscles controlling the eye are affected in such a way that the eye drifts outward and slightly downward and has difficulty turning inward and upward. The upper eyelid of the affected eye usually droops, and the pupil may be enlarged. Trochlear paralysis causes a vertical deviation of the affected eye. Abducens nerve paralysis affects another muscle, causing the affected eye to turn inward toward the nose and preventing it from turning fully outward.[5]