When people think about neuromuscular disorders, eye problems usually aren't the first thing that comes to mind. That makes sense, because most eye problems in neuromuscular disease are, thankfully, not too severe, treatable with therapy for the underlying disorder, or correctable with special lenses or surgery. But in some disorders, problems can persist, and they range from nuisances to major impediments to quality living.

Not too surprisingly, weakness of the muscles that control the eyeballs or those that open and close the eyes is probably the most common eye problem seen in an MDA clinic.

This weakness can stem from deteriorating muscles themselves, as in muscular dystrophies and other muscle disorders; abnormalities in parts of the brain that have to do with eyes and eye muscles, as, for example, in some mitochondrial disorders; or a problem in the communication between nerve and muscle, as is the case in various types of myasthenia. Results in all three types of weakness can be similar, but depend, of course, on the particular muscles involved.

Drooping Lids: Surgery Is Easy
'When Somebody Knows How to Do It'

One muscle that's often affected has a long name with a simple meaning. It's called the levator palpebrae superioris, which literally means "lifter of the upper eyelid," and that's just what it normally does.

Weak levators are common in some neuromuscular diseases, particularly myotonic muscular dystrophy (MMD), myasthenia gravis (MG), congenital myasthenic syndromes, mitochondrial disorders and, most strikingly, in oculopharyngeal muscular dystrophy. In OPMD, as its name implies, weakness of ocular muscles is a defining characteristic.

When levators are weak, explains ophthalmologist Francois Codere, a condition known as ptosis, a drooping or dropping of the eye, results.

Codere, who practices ophthalmology and eye surgery at the Royal Victoria Hospital in Montreal, specializes in surgery to correct drooping eyes. He sees the problem frequently in Montreal, Quebec, in the heart of French Canada. Quebec has the highest OPMD incidence in the world.

Better understanding of the course of OPMD thanks to genetic and other discoveries in recent years has allowed surgeons like himself to better plan the nature and timing of a patient's surgery, Codere says.

One way to "strengthen" the levator muscle is by shortening it and pulling up on it. Known as a levator resection, this procedure is often done when levators are weak in stable, nonprogressive conditions. "If the levator is strong enough, we can just shorten it as you would tighten a loose elastic, by taking out a piece of it and reattaching it to the eyelid," Codere says. (The surgery doesn't really strengthen, but rather tightens, the muscle.)

But in most people with OPMD, particularly those whose course is predicted to progress rapidly (easier to do now, he says), the results are likely to be unsatisfactory.

"Since that muscle is sick in this disorder, and it's a progressive disorder, unfortunately that operation often only gives a temporary relief of the symptoms," Codere says. "It lifts the eyelid, but there's a tendency for it to droop again over the next five to 15 years."

A small muscle called the levator palpebrae superioris opens the eye, while the circular orbicularis oculi closes it. When the levator is weak, the frontalis can sometimes be used to hold the eye open.

For this reason, Codere prefers a different operation, called a frontalis suspension because it makes use of the large frontalis muscle in the forehead, which maintains its strength in OPMD.

Codere says, "The strategy is to use the movement of the brow and transmit it to the lid edge. The way we do that is by passing a kind of suspenders between the brow and the eyelid, so that when the patient lifts the brow, the lid edge will lift."

MDA grantee Guy Rouleau, a neurologist and neuroscientist at Montreal General Hospital and a colleague of Codere's, says such surgery can be "very, very effective" and usually lasts for many years. "In my experience, people do absolutely fine," he says, but notes that he's in a place where OPMD is well understood and easily recognized.

Problems sometimes occur with ptosis surgery when it's attempted by a plastic surgeon without much experience in the procedure, Rouleau says. He recommends finding someone who specializes in this type of surgery, such as an oculoplastic surgeon (Codere's specialty). "Up here, we see a lot of these patients, and the eye thing is a trivial problem, easily corrected. Well, it's easy when somebody knows how to do it."

A Child Copes With Low Vision and Mitochondrial Disease Carl Mason was 18 months old when his mother, Terri, began to notice that his eyes were always wiggling back and forth, a symptom known as nystagmus. "It was worse in some positions than others, but it was happening pretty much all the time," Mason remembers. "We went to the ophthalmologist, who did a complete eye exam and thought it might be a brain tumor. We ruled out the brain tumor with an MRI scan, and they had us come back every couple of months for a while." On one of those visits, the eye doctor noted something else: The optic nerve in each of Carl's eyes was getting smaller (atrophying), and he was losing vision. "The nerves continued to atrophy for about a year, at which time they stopped. His vision has been stable since then," says Mason, "but it's about 20/250 [meaning he has to be at 20 feet or closer to see something most people could see from distance of 250 feet], and they can't correct it." Carl's diagnosis eventually became clear. He has Leigh's syndrome, a mitochondrial muscle disorder that can affect the visual system. Carl is now 8, and although his disease continues to take its toll on many of his functions, he also seems to be showing signs of improvement. "When Carl first lost vision, his vision measured much lower than it does now because he didn't know how to use what he had," Mason says. She attributes much of that knowledge to the help of vision teachers, certified specialists who have helped Carl through the public school system in Portland, Ore., where he's now in a special education classroom in second grade. Vision teachers, Mason explains, teach the child to use the vision he or she has rather than focusing on improving vision. They teach orientation and mobility -- "how to get from point A to point B," Mason says -- and help the child become as independent as possible. They look at classroom materials to see which ones need to be modified, and make sure that a child has the right computer keyboard and monitor. "When we first found out, the tendency was to protect him," Mason says. "But you can't hover. I did that for a long time. I would hover at the jungle gym waiting to catch him if he fell. But they're really a lot more resilient than you think they are. You can back off more than you think before jumping in to help." Carl is doing better than expected for someone with his diagnosis, Mason says. He's gotten weaker, but he can still walk, and she believes his IQ test will show improvement this year. "Carl has an incredible sense of direction," she says. "Whenever we go to a doctor's office, I invariably get lost in the maze of hallways. He'll lead me out every time."

Surgery, however, isn't for everyone. Sometimes a patient's condition isn't fit for surgery, and many times the weakness in the levators is rapidly progressing or fluctuating.

In some situations, such as myasthenic disorders (congenital myasthenic syndromes, which are genetic; or autoimmune myasthenia gravis, which results from an immune-system attack on muscle cells), the solution is to treat the patient with medications and hope the eye problem clears up. It usually does.

In the meantime, temporary solutions, such as "ptosis crutch" eyeglasses, can be employed. These support the eyelids for reading, driving or watching television. They shouldn't be used for too long a time at a stretch, because they can lead to drying of the eye, but they work well for some situations and some patients.

Of course, some people bypass fancy solutions.

Ptosis crutch eyeglasses can help compensate for weak levator muscles as long as they're not used for prolonged periods.

"I had an older myasthenic patient, a man in his 70s who ended up using Scotch tape on his lids," says neurologist David Chad, who directs the MDA clinic at University of Massachusetts Memorial Health Care in Worcester. "That's the crutch I'm most familiar with. The only worry is that if you keep the eye open, you can have a corneal abrasion [scratch on the cornea, the covering of the eyeball]. But a lot of ophthalmologists hesitate to do surgery in this disorder because of the fluctuating course."

In children, a severely droopy eye can affect development of the still immature visual system. The brain needs normal visual input from an open eye in order to develop all the right connections between the eye and the brain (see "Lazy Eyes"). For this reason, it's crucial to treat a droopy eye in a child if at all possible.

When Eyes Won't Close:
Prevention Better Than Treatment For Dry Cornea

The muscle that closes the eye is a circular one (see illustration above) called the orbicularis oculi, Latin for "little circle around the eye."

Weakness of this muscle doesn't occur as often in neuromuscular disease as does weakness of the levator palpebrae, but it can be a problem, particularly in facioscapulohumeral muscular dystrophy. In this form of MD, which involves weakness of several facial muscles, weakness of the orbicularis oculi muscles can keep the eyes from closing completely. That can be a serious problem during sleep, because the cornea -- which covers the front of the eyeball like the glass on a watch -- is left partially exposed all night, allowing it to become dry or scratched.

Eye surgery to lift the upper eyelid, if done incorrectly so that the lid is pulled up too high, is another common cause of difficulty with eye closure.

Symptoms of a dry cornea are a gritty or burning sensation in the eyes, as well as red or watery eyes.

Incomplete eye closure can be managed by wearing an eye mask during sleep and lubricating the eye with drops or ointments during the day and before sleep, Codere says.

A dry cornea can become infected -- a "disastrous" situation, Codere notes, one that's better avoided than treated. In extreme cases, the patient may have to wear goggles to keep moisture from evaporating around the eyes, at least temporarily. Surgery to lift the lower lid can be done, but results aren't always satisfactory.

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