Ophthalmology

Last Friday Carson had an appointment with an ophthalmologist.  When he was born we noticed that when he would look to the right his left eye would cross in the middle, making it look like he was staring at his nose.  Mike and I never took much notice to this because he had already had so many doctors and appointments and it didn't seem to bother him.  Plus it didn't happen all the time, it was just if he looked really hard to the right.

Last year at Carson's genetics appointment I decided to mention it to his doctor.  To my surprise, he became very concerned.  He told me that he needed to see a cardiologist to check his heart and an ophthalmologist for his eyes.  He said out of the two the ophthalmologist was the one I should see first.  Again, I thought it may just be a lazy eye muscle and I left there confused.

At our first appointment we saw a woman who was wonderful with Carson.  Because he doesn't speak we had to get creative in the way we were able to get answers out of him.  Instead of saying, "what do you see?" we would have to ask, "where is the _____________" and see if he could point to it.  Doing this we were able to test his depth-perception and check to see if he is color-blind.  Both were normal.

Actually doing the eye test was a little harder.  For one, they dilated his eyes.  Carson is very light sensitive already because of his SPD.  They were nice to let us stay in the room with the lights out until it was time to be seen.  Usually they make kids go back out into the waiting room.  After the half hour needed to wait they came back to do the exam. 

Carson is always very worried when it comes to people getting close to him.  (I know that this is because of his first ENT that he had when he was little and the guy actually held him down to poke around in his ears.  Trust me-that won't ever happen again.)  He has a tendency to scream and kick and try to push people away.  I basically have to put him in a choke-hold and hold his legs back with mine so she can get close enough to see.  In holding his head still and making his eyes track an object from one side to the other, she gave me her preliminary diagnosis: Duane Syndrome.  I had never heard of this, or at least I didn't think that I had.

Below is an outline of Duane Syndrome.

Duane Syndrome

What is Duane syndrome?

Duane syndrome, also called Duane retraction syndrome (DRS), is a group of eye muscle disorders that cause abnormal eye movements. People with Duane syndrome have difficulty rotating one or both eyes outward (abduction) or inward (adduction).

How do normal eye movements occur?

Six muscles, which control the movement of the eye, are attached to the outside of the wall of the eye. In each eye, there are two muscles that move the eye horizontally. The lateral rectus muscle pulls the eye out towards the ear and the medial rectus muscle pulls the eye in towards the nose. There are four other muscles, which move the eye up or down and at an angle. Each eye muscle receives the command for movement from cranial nerves that exit the brain.

What is the cause of Duane Syndrome?

Duane syndrome is due to miswiring of the eye muscles. The “mistake” probably happens around the 6th week of pregnancy and is due to poor development of tiny parts of the brain stem that control the eye muscles.
In Duane syndrome, the sixth cranial nerve that controls the lateral rectus muscle (the muscle that rotates the eye out towards the ear) does not develop properly. Why the nerve does not develop is not yet understood. Thus, the problem is not primarily with the eye muscle itself, but with the nerve that transmits the electrical impulses to the muscle. There is also irregular innervation of a branch from the third cranial nerve, which controls the medial rectus muscle (the muscle that rotates the eye toward the nose). This is why abnormalities may be found in both left gaze and right gaze.

Who gets Duane syndrome?

Duane syndrome affects girls more often than boys. In addition, the left eye is more often involved than the right eye. The reason for this is not known. Around 20% of Duane syndrome patients have both eyes affected. No particular race or ethnic group is more likely to be affected.

What are the other characteristics of Duane syndrome?

• Strabismus-the eyes may be misaligned and point in different directions at all times
• Head position-patients often maintain a head posture or head turn to keep the eyes straight
• Amblyopia-reduced vision in the affected eye.
• Eyelid narrowing-the affected eye may appear smaller than the other eye
• Upshoot or downshoot-with certain eye movements, the eye may occasionally deviate upward or downward

Is Duane syndrome congenital (present from birth)?

Duane retraction syndrome is present from birth, even if it is not recognized during infancy. An abnormal head posture and strabismus are often visible in old photographs taken in early childhood.

Is Duane syndrome hereditary?

In 90% of cases, the patient has no family history of Duane syndrome. Ten percent of patients will have an affected family member and these tend to be cases where both eyes are involved. There is currently no test that can determine whether a patient has a hereditary form.

Are there different types of Duane Syndrome?

Duane syndrome is often characterized by whether the primary abnormality is a reduced ability to turn the affected eye(s) outward (type I), inward (type II), or both (type III). Type I is the most common form of Duane syndrome. and affected patients will characteristically have a head turn towards the involved side, and will appear esotropic (crossing inward) in straight ahead gaze.

Do Duane syndrome patients have other eye problems?

The problem with the 6th cranial nerve is usually an isolated condition and the child is usually otherwise completely normal. With careful follow-up, the long-term prognosis for good vision is usually excellent.
Occasionally, Duane syndrome may be found in association with other eye problems, including disorders of other cranial nerves, nystagmus (an involuntary back-and-forth movement of the eyeball), cataract, optic nerve abnormalities, microphthalmos (abnormally small eye), and crocodile tears.

Do Duane syndrome patients have non-ocular medical problems?

Not usually, however, some patients with Duane syndrome have other problems, such as hearing impairment, Goldenhar syndrome, spinal and vertebral abnormalities. There is also an increased frequency of Duane syndrome in patients with thalidomide exposure.

When is Duane syndrome treated?

For the majority of patients, Duane syndrome does not require surgical treatment. Surgery for Duane syndrome is indicated for one of four reasons:
• To reduce strabismus
• To eliminate a socially unacceptable head position
• To eliminate a significant upshoot or downshoot.
• To eliminate disfiguring enophthalmos.
The goal of treatment is to restore satisfactory eye alignment in the straight-ahead position, eliminate an abnormal head posture and to prevent amblyopia. In most cases, eye muscle surgery is required. Because the function of the affected nerve and muscle cannot be restored, the other eye muscles are adjusted to compensate and allow for better eye alignment.

How successful is surgery for Duane syndrome?

Surgery cannot fix the problem of nerves that are miswired.  By moving the eye muscles surgery can compensate for the miswiring. Because surgery doesn’t “really” fix the problem, surgery cannot restore normal eye movement, but surgery can (and usually does) substantially improve the situation. The full effect of the surgery may take some weeks to become apparent.  There is a low incidence of unexpected or inadequate results.

The interesting part of all of this is that I thought that his left eye was the problem because of the way it turns inward.  I was wrong.  His right eye can't turn all the way outward when he is looking to the right so the left eye LOOKS like it is crossing because it tracks the way it is supposed to and the right eye stops at a certain point!  Because of this he cocks his head slightly to the right to align his eyes to see correctly.

So we left the office into the bright world with instructions to follow-up in 6 months with a different ophthalmologist in the practice to get a second opinion and if he agreed then this was the final diagnosis.  Not the end of the world, just one more thing to add to the list of my interesting little guy.  We hid for the rest of the day (only about an hour) at the mall that was close to the office to give his eyes a break from the sun.  Unfortunately, his eyes were dilated for three days!!

When we went for that second appointment Carson would not cooperate.  The didn't dilate his eyes this time but I think since we were seeing a man it freaked him out.  This doctor was not convinced.  He said that because Carson's face isn't symmetrical, he thought it was just an optical illusion that his eyes weren't tracking together.  He asked us to wait another 6 months and return.  At this appointment they would dilate his eyes again and hopefully we would know 100% what was going on.  So that was this appointment.

We were able to get an eye test this time.  She had me sit in the exam chair with him on my lap.  We had him use his finger and 'draw' the letter that he saw on the screen.  It was cute because the letters were in boxes that had open sides.  When he would write the letter he would include the two sides of the box: / L / .  It was cute.  He was able to see them until they were really small, almost to the point where even with my contacts I was having to squint to see them.  When it came time to dilate his eyes I warned her that his eyes had stayed dilated for so long last time.  The girl was really nice.  She apologized and used a milder drop in his eyes.  This time they did not let us wait in the room in the dark but I had come prepared.  I brought his stroller and towels.  We sat in the bright waiting room with the hood of his stroller blocking the light from above and towels on the top of that blocking the sides.

                    This is in the waiting room, looking a little high.  Look at those pupils!!

When we they were ready we went back to the room again and this time the doctor was able to get a better exam out of Carson.  We ended up using his iPad to use as our tracking object.  So we have our final diagnosis.  It is Duane Syndrome.  As of now he doesn't need glasses or surgery which is great.  Although, with a missing cranial nerve it's not like you can just put one in so I'm not really sure what surgery would do anyway.  We go back in a year.

On a side note I did end up finding out on Facebook that there is one other little boy who is around Carson's age (with his deletion) who was also diagnosed with this.  It's funny that both these boys already carry very rare diagnoses but now have another rare diagnosis on top of the other one.

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