Figure 1 : Subtle right face turn.
The patient is a 10-year-old boy who was noted in infancy to have an eye movement abnormality. His parents think he has a slight right face turn. He does not complain of diplopia. He is in good general health.
His only ocular treatment has been occlusion therapy for strabismic amblyopia in his left eye and glasses for compound myopic astigmatism in bodi eyes.
His best-corrected visual acuity is 20/20 OD and 20/50 OS. His current prescription is: OD -2.00 +2.50 at 95° and OS -3.00 +1.25 at 120°. There is about a 5° right face turn (Figure 1). Prism and cover testing in primary position shows 8 prism diopters (?) of right hypertropia in the distance and 4 Δ at near. Adduction of die left eye is mildly limited. He can abduct die left eye just past the midline. There is extreme downshoot and mild upshoot of the left eye with adduction. When he looks to die right, the left globe retracts and the palpebral fissure narrows (Figure 2). He is not aware of diplopia in any gaze position. He has gross stereopsis (Titmus fly). The anterior segment and fundoscopic examinations are normal.
In summary, the patient is a 10-year-old boy with Duane syndrome OS. He has very significant globe retraction and palpebral fissure narrowing wirh adduction of die affected eye. His slight right face turn does not present a problem, but his parents are interested in improving the disfigurement of his eyes when he looks to die right.
Emilio C. Campos, MD
This young man's problems are the following: 1) lack of abduction of die left eye, 2) head turn to the right, 3) retraction of the left globe in adduction, and 4) downshoot and upshoot of the left eye in adduction.
It is obviously impossible to create abduction in a case of Duane syndrome. The elements that can be addressed are the other three problems.
His head turn is due to die fact that gross binocular cooperation is present with the left eye in adduction. If no binocularity were present, one would not have expected an anomalous head posture. Although there is a mild limitation of adduction of die left eye, an improvement of both die left esotropia and the head turn can be obtained by weakening the left medial rectus muscle with a recession. In fact, despite die rigid didactic classification of Duane syndrome into types I, II, and III, limitation of adduction often is observed in Duane type I syndrome. Recession of the medial rectus muscle of die left eye, therefore, has to be performed in die presence of esotropia and a right face turn.
Retraction in adduction is improved by equal amounts of recession of the two horizontal rectus muscles. In this case, both the medial and lateral rectus muscles have to be recessed. Usually 5 mm of recession of the medial rectus and 5 mm of recession of the lateral rectus muscles are performed for this purpose. Because the medial rectus muscle also needs a recession for correcting the esotropia and the head turn, the amount of recession for this muscle has to be doubled. This means that the medial rectus muscle has to be recessed 1 1 mm and the lateral rectus muscle 5 mm. It has to be noted that the lateral rectus muscle, although incapable of inducing abduction, still contracts when the eye is adducted.
Figure 2: Slight right hypertropia in primary position (A). Downshoot of left eye on gaze to right (B). Limited abduction of left eye (C).
Downshoot and upshoot of die eye in adduction are probably due to the fact diat in patients with Duane syndrome, die eyeball slides vertically when both horizontal rectus muscles contract. The eye more often moves toward elevation (upshoot) and rarely toward depression (downshoot). In dus case, die downshoot prevails. Surgery on the oblique muscles seems unwarranted, whereas weakening of the lateral rectus muscle is effective borh for die up- and die downshoot. A splitting of the lateral rectus has been proposed by Jampolsky. The lateral rectus muscle is split for a lengdi of 10 mm after detachment from the globe. The two arms of die muscle are men reinserted with a "V" shape 3 mm above and 3 mm below the original insertion. This applies when up- and downshoot are the only problem.
In the presence of retraction of the globe in adduction, a recession has to be added to the splitting. In my experience, mis operation has proven to be extremely effective and easy to perform. I have operated on more than 30 cases with excellent results. It is still debated whether the splitting is really necessary and whedier a simple recession of the lateral rectus muscle would achieve the same results. Many surgeons just recess this muscle and claim positive results. I have no personal experience with this approach.
To summarize, the head turn and esotropia can be corrected by a recession of the left medial rectus muscle. Retraction of the globe in adduction is correctable with a recession of both horizontal rectus muscles of the left eye. Finally, up- and downshoot can be corrected by splitting the left lateral rectus muscle. For this patient, I would do die following: 13 mm recession of the left medial rectus muscle and 5 mm recession and splitting of the left lateral rectus muscle.
Surgery on the fixing eye in Duane syndrome is unwarranted, although it has been advocated by some. There is no proof of its benefits, and the potential risks of perforation of the eye with a posterior fixation suture in the fixing eye cannot be justified. Transposition procedures on the affected eye are not indicated as well because there is no proof of their benefit.
R. Scott Foster, MD
This young patient presents with classical features of a left unilateral Duane syndrome including markedly limited abduction and modesdy limited adduction with retraction and lid fissure narrowing. Additionally, a prominent abrupt downshoot and a mild upshoot are present. These latter features are characteristic of the mechanical "leash" or "bridle" effect of a tight cocontracting lateral rectus muscle. Coexisting innervational cyclovertical anomalies do not appear to be involved.
Surgical treatment of Duane syndrome is usually based on correcting any or all of the following conditions: an abnormal compensatory face turn associated with a deviation in die primary position (usually exotropia or esotropia), globe retraction (lid fissure narrowing) on attempted adduction, die presence of an alphabet pattern (A, V, Y), and significant upshoot or downshoot in adduction.
With this child, the main concern is with the adduction anomalies, mainly die downshoot and retraction. The mild right face turn and hypertropia do not appear to be a problem.
In general, recession of die coconrracting lateral rectus muscle alone or in combination with its antagonist medial rectus muscle will reduce the adduction retraction. The amount of surgery required is dependent on die severity of retraction, any deviation in primary position, and forced duction testing.
Mechanical vertical deviations in adduction can be reduced with large antagonist horizontal rectus muscle recessions, lateral recrus muscle posterior fixation sutures, or a "Y" split of the lateral rectus muscle. The recession reduces the cocontraction tone, while vertical slippage is limited with die fixation sutures or the "Y" split of the latter two procedures. I believe the "Y" split is more effective.
Surgical correction for this patient must address the adduction anomalies (retraction and prominent downshoot), while not inducing a deviation in the primary position. I would recommend recessing bodi die medial rectus muscle and the lateral rectus muscle an equal amount while performing a "Y" split of the lateral rectus muscle. Forced duction testing of both the horizontal rectus muscles would dictate the amount of recession I would perform. Assuming no medial rectus contraction and a mild to modest lateral rectus muscle restriction, I would anticipate recessing the muscles 5 mm each. If forced duetions revealed more significant restrictions, I would increase the amount of the recession accordingly. With this procedure, I would anticipate a significant reduction in the adduction downshoot and a mild to modest decrease in the retraction on adduction with no significant alignment change in the primary position.
The parents would be informed of the above goals with the provision that further surgery may be necessary if there is an alignment shift in the primary position.
Lionel Kowal, MD
If the parents brought this child to me, I would strongly recommend mat he have no surgery at this time. There is no reliable way to substantially improve this boy without putting him at risk of new problems.
If he were older and came to my office wishing ro improve his appearance, then I would offer him an operation where I recessed bodi the left lateral and medial rectus muscles on adjustable sutures. This may result in less retraction and less downshoot on adduction.
I am, however, very concerned diat he already has underaction of both these muscles. The left medial rectus has approximately 2 mm of version deficit, whereas the left lateral rectus abducts approximately 60%. I have converted patients like him into patients with an even smaller range of movement (following die surgery that I have suggested) with troublesome diplopia on lateral gaze. Sometimes these patients are better on day one (when die sutures are adjusted) dian 2 weeks later. These are not happy patients.
I have been tempted (by die anecdotal experience of orhers) to try Botox to the left medial rectus muscle in patients such as this. I have been trying to "sell" this as a treatment/investigation for some years, but have not yet "sold" even one such intervention. It would allow die patient and me to judge how likely die potential problem of right gaze diplopia would be if he were to have any weakening of the left medial rectus muscle. If right gaze diplopia was not a bodiersome issue at all during the period of left medial rectus muscle palsy, then I would feel more comfortable about the above surgical intervention. Again, diough I find this investigation/treatment to be intellectually attractive, but personal experience is entirely lacking.
The degree of amblyopia is unusual for Duane syndrome. There is approximately 1.75 D of anisomyopia, which is not particularly amblyogenic, and should have responded to occlusion dierapy in the past. I would take a history of when the last occlusion therapy was carried out and consider initiating some more at this time. Prior to doing so I would quantitate his suppression scotoma with die Bagolini Filter Bar and would not proceed if this suggested a risk of diplopia.
Not surprisingly, all three discussants would manage die patient's strabismus in radier similar ways. Dr Campos advocates a larger left medial rectus muscle recession than die others, although Dr Foster may do more if forced auctions revealed a tight medial rectus muscle. Dr Kowal would use adjustable sutures on both the medial and lateral rectus muscle recessions. Drs Campos and Foster would split the lateral rectus muscle in addition to recessing it to counteract the upshoot and downshoot in adduction; Dr Kowal feels that recessing it will suffice.
None of the discussants believed surgery on the eye was indicated in this case, and Dr Campos generalized this to cases of Duane syndrome. none of the discussants mended a transposition to improve abduction of the eye, a procedure that Dr has had experience with in Duane syndrome patients
Dr Kowal expressed tance to do any surgery on patient because of concern the child may not show any improvement with surgery and could develop problems such as diplopia on right gaze. He raised the possibility of temporarily paralyzing the left medial rectus musele with Botox to determine whether the patient would have diplopia in right gaze,