Rectus Muscle Recessions for the Treatment of Congenital Nystagmus

Large

Gunter K.

von

Noorden, MD, Derek T. Sprunger, MD

\s=b\ Retroequatorial recessions of the horizontal rectus muscles 10 to 12 mm behind their insertions reduced the amplitude of manifest congenital nystagmus in three patients. Modest improvement of visual acuity occurred in two patients. In a third patient with periodic

alternating nystagmus,

a

compensatory

head turn was eliminated by shifting the neutral zone of the nystagmus to the primary position of gaze. In spite of large recessions of the muscle insertions, none of the patients had a functionally significant postoperative limitation of ocular motility.

(Arch Ophthalmol. 1991;109:221-224)

Qurgical

treatment of nystagmus is usually limited to correcting the secondary compensatory head posture. Operations directed at the nystagmus itself, ie, attempts to stabilize the eyes to obtain better visual acuity, to de¬ crease oscillopsia, or to gain cosmetic improvement are less commonly per¬ formed. Among the surgical methods

mentioned in the older literature to accomplish these goals are fixation of the extraocular muscles to the perios¬ teum of the lateral orbital wall,'" trans¬ position of parts of the horizontal and vertical rectus muscles,' or a free tenotomy of opposing rectus muscles.4 However, none of these procedures has gained much popularity. Our at¬ tempts to dampen the nystagmus amAccepted for publication August 9, 1990. From the Cullen Eye Institute, Baylor College of Medicine, Houston, Tex, and the Ophthalmology Service, Texas Children's Hospital, Houston. Dr Sprunger is now with the Midwest Eye Institute, Indianapolis, Ind. Reprint requests to Ophthalmology Service, Texas Children's Hospital, Box 20269, Houston, TX 77225 (Dr

von

Noorden).

plitudes by retroequatorial myopexy of

all four horizontal recti"'" have been unsuccessful. The more recently devel¬ oped approach of employing the stabi¬ lizing effect of fusional convergence on

nystagmus amplitudes by surgically

an artificial exotropia7"9 needs further study and documentation be¬ fore it can be accepted as a valid mode of treatment. Bietti1" and Bietti and Bagolini" re¬ ported that nystagmus intensity can be decreased by retroequatorial recession (12 mm) of the horizontal rectus mus¬ cles in one or both eyes. These authors noted appreciable improvement of vi¬ sual acuity in nine of 14 patients who underwent surgery." However, this procedure has received little attention until its recent revival by de Brown E. Limon and Bernadeli J. Corvera.12 We report herein our experience with this operation in three patients with manifest congenital nystagmus. The operation was performed to de¬ crease a cosmetic problem in two pa¬ tients and to correct an alternating face turn in a third patient with period¬ ic alternating nystagmus.

creating

PATIENTS AND METHODS

Electronystagmograms were recorded patients before and after surgery using a dynograph, coupled with a direct nystagmus transducer in the AC mode, with a time constant of 3 seconds. The highfrequency filter was 25 Hz, with a sensitiv¬ ity of mV/mm. With calibration, this corresponded to 1 mm of deflection per 2° of for three

eye movement in case 1 and to 1 mm of deflection per Io of eye movement in cases 2 and 3. The calibration was the same for preoperative and postoperative recordings in all patients. Skin electrodes were posi¬ tioned at all four canthi and a ground elec¬ trode was attached to the patient's fore¬ head. The patient's head was placed in a

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chin rest and the forehead was supported a headrest while the eye movements were recorded. Rectilinear tracings were obtained while each patient fixated with both eyes in the primary position on a fixation light at 100-cm fixation distance. In case 3, recordings were also obtained with the eyes in 30° dextroversion and levoversion.

by

REPORT OF CASES

CASE 1.—A 17-year-old white girl was referred because of poor visual acuity and nystagmus. Some of her clinical findings have been published previously.1'1'4'" Her visual acuity measured on the Snellen chart at 6-m fixation distance was 20/200 OD, 20/100 OS, and 20/80 OU with the following optical correction: -1.25 spherical, +2.25 cyl., axis 125° OD; and -2.00 spherical, + 2.75 cyl., axis 50° OS. Visual acuity at 33-cm-fixation distance was 20/50 OU. Pre¬ operative and postoperative visual acuity determinations were carried out by the orthoptiste in our department for all pa¬ tients described in this study. The patient had a conspicuously coarse, large-amplitude, and low-frequency mani¬ fest nystagmus (Fig 1), which, according to her history, had been present since birth. She complained about poor distance vision and the unfavorable cosmetic effect of hav¬

ing "roving" eye movements.

The remainder of the examination showed orthotropia at near and distance fixation and absence of stereopsis on the TNO stereo test. She had a hypopigmented appearance of the fundus with poor ophthal¬ moscope definition of the foveal reflex. However, her skin was tanned and her hair and eyebrows were brunette. The diagnosis of ocular albinism was made. The patient underwent a 10-mm reces¬ sion of all four horizontal rectus muscles in one session. Immediately after surgery, she noted improvement of visual acuity. One year after surgery her corrected visual acuity was 20/80 OD, 20/70 OS, and 20/70 OU. Her binocular near visual acuity was 20/40. She remained orthotropic and was still stereoblind. Being a keen huntress, she

Visual Acuity Before and After Surgery

Preoperative

Postoperative Follow-up,

Case_Right Eye_Left 1

20/200

2

20/400

Eye

20/100 20/200

Both

Near_Right Eye_Left Eye_Both Eyes_Near

Eyes

20/80 20/200

20/50 20/70-100

Right Eye

20/80 20/200

20/70 20/200

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20/70 20/200

Right Eye

20/40 20/40

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Left

Eye

-/wVjvwWv' Fig 1.—Case 1, Binocular nystagmogram before (A) and after (B) surgery. Note the decrease of amplitude after surgery.

Fig 2.—Case 2, Binocular nystagmogram before (A) and after (B) surgery. Note the decrease of amplitude but slight increase of frequency after surgery.

especially pleased by a considerable improvement of her markswomanship. A comparison of preoperative and postopera¬

with a persistent V-pattern in downward gaze. The patient returned 2 years later at age 18 years with a variable consecutive exotropia of 30 prism diopters at distance and orthotropia at near fixation. From a cos¬ metic point of view this consecutive devi¬ ation did not bother him but he had become increasingly self-conscious about the roving eye movements and requested further sur¬ gery to make this problem less conspicuous. The second operation consisted of a bilat¬ eral inferior oblique myectomy to correct the V-pattern, additional recession of both medial rectus muscles of 4 mm, and a 12-mm recession of both lateral recti to reduce the nystagmus amplitudes. Taking the effect of the first operation into account, all four horizontal rectus muscles were thus recessed a total of 12 mm behind their original insertions. Nine months after surgery the consecu¬ tive exotropia was unchanged and still did not present a cosmetic problem. The pa¬ tient's visual acuity was now 20/200 OD and OS and with both eyes open. His near visual acuity was 20/40 and stereopsis was absent. The patient had noted a marked subjec¬ tive improvement of visual acuity, com¬ mented on his ability to read faster and recognize objects more quickly, and was pleased with the cosmetic result. The elec¬ tronystagmogram recorded 6 months after surgery showed a decrease of the nystag¬ mus amplitude but an increase in its fre¬ quency (Fig 2). No limitation of ductions or versions was noted. The preoperative and postoperative visual acuities of patients 1 and 2 are summarized in the Table. CASE 3.—A 5-year-old white boy pre¬ sented with a history of spina bifida, hydrocephalus, and partial optic atrophy in the

was

tive ductions and versions showed minimal limitation of adduction in both eyes after surgery. The electronystagmogram record¬ ed 19 months after the operation showed a decrease of the nystagmus amplitudes

(Fig 1).

CASE 2.—A 16-year-old white boy pre¬ sented with a complaint of "roving" eyes, poor vision, and light sensitivity. His best corrected visual acuity was 20/400 OD and OS and 20/200 OU at 6-m fixation distance. His visual acuity with both eyes open at 33 cm varied between 20/70 and 20/100 at different examinations. A cycloplegic re¬ fraction showed a simple myopia of -3.50 spherical in the right eye and -4.50 spheri¬ cal in the left eye. The patient had 30 prism diopters of esotropia at near and distance fixation with a V-pattem, measuring 40 prism diopters in downward gaze and 20 prism diopters in upward gaze. Ductions and versions showed marked overaction of both inferior oblique muscles. Stereopsis was absent. An electronystagmogram showed a manifest congenital nystagmus in primary position and lateral gaze. The nys¬ tagmus pattern with eyes in primary posi¬ tion is shown in Fig 2. Slit-lamp examination showed aniridia in both eyes and examination of the fundus revealed a poor ophthalmoscopic definition of the foveal wall reflex in both eyes. In the absence of aniridia in the mother and of a positive family history for aniridia, the di¬ agnosis of autosomal dominant aniridia was made. The patient underwent an 8-mm recession of both medial rectus muscles to correct the esotropia. This caused ocular alignment at near and distance fixation,

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Fig 3. —Case 3, Before surgery, fast phase tov the right in 30° dextroversion (A); fast phase to the right in primary position (B); and neutral zone in 30° levoversion (C). right eye. His unconnected visual acuity was 20/30 OD and OS at 6-meter fixation dis¬ tance and his near visual acuity was 20/20 with both eyes open at 33-cm fixation dis¬ tance. He had no stereopsis. Cycloplegic refraction showed an insignificant hypermé¬ tropie refractive error. The patient had a manifest congenital nystagmus with an al¬ ternating face turn to the right or left, the direction of the face turn changing every 2 to 3 minutes. With the head passively straightened, the patient developed inter¬ mittent esotropia of variable degrees (nys¬ tagmus dampening by convergence).

'

The remainder of the eye examination results were normal except for a slight temporal pallor of the right optic nerve head. The diagnosis of periodic alternating nystagmus was made. The patient was fol¬ lowed up for nearly 2 years and the periodic alternating nystagmus remained unchanged during this time. However, an A-pattern exotropia that had developed in downward gaze responded well to a tenectomy of both superior obliques at age 7 years. At age 10 years the patient had become sufficiently

cooperative to undergo electronystagmography, which demonstrated the character¬ istically changing directional pattern of pe¬ riodic alternating nystagmus. Figure 3 shows the nystagmus having a fast phase to the right in 30° dextroversion and in prima-

ry position. A neutral zone was present in 30° levoversion and the patient assumed a face turn to the right of approximately 30° during this phase of the nystagmus. Three minutes later the direction of the

nystagmus had shifted and the electronys¬ tagmogram showed a nystagmus with a fast

phase to the left in the primary position and

left gaze and marked decrease of the nys¬ tagmus in 30° dextroversion (Fig 4). During this phase the patient assumed a face turn of approximately 30° to the left. In an effort to dampen the nystagmus and improve the compensatory head posi¬ tion, an 11-mm recession of all four horizon¬ tal rectus muscles was performed. Six months later the alternating head turn was no longer present. The nystagmus pattern had changed dramatically inasmuch as there was marked improvement of the nystagmus with the eyes in the primary position (Fig 5). In 30° dextroversion the

nystagmus was beating with a fast phase to the

right, and in 30° levoversion the fast phase was to the left. The patient, who was 11 years of age at

the time of this report, volunteered the information that his reading speed had much improved since the operation. His visual acuity was unchanged and he had remained orthotropic but still had no stereopsis. Preoperative and postoperative duc¬ tions and versions in lateral gaze showed only moderate limitation of abduction and adduction of each eye (Fig 6). COMMENT

The

of the rectus muscle to depends on the leverage existing between the center of rotation and the line of pull of the muscle at the tangential point of contact with the globe.a*48SI By retroplacing the muscle

ability

rotate the eye

insertion behind the equator and thus posterior to the tangential point, the leverage is decreased and a given amount of muscle innervation will have less rotational effect on the globe. In cases of nystagmus this will cause its amplitude to decrease. Retroequator¬ ial recession of the horizontal recti reduced the nystagmus in cases 1 and 2 and shifted the null zone from dextro¬ version and levoversion to the primary position in a patient with periodic al¬ ternating nystagmus (case 3). The im¬ provement of measurable visual acuity in cases 1 and 2 after reduction of the

nystagmus was only modest, especially in case 2, and not too much emphasis

should be placed on this unexpected benefit from the operation. It is well known that visual acuity in the pres¬ ence of nystagmus may vary during different examinations, depending on the patient's effort and state of anxi¬ ety. Nevertheless, the subjective im¬ provement of visual acuity and espe¬ cially the reported ability to read and recognize objects more quickly is note¬ worthy and deserves further study. Cosmetic improvement was unques¬ tionable, however, and both patients were satisfied with the decrease of their nystagmus amplitude. In patient 3, who had periodic alter¬

nating nystagmus, surgical treatment brought relief of a compensatory ab¬

Fig 4. —Case 3, Before surgery, fast phase to the left in 30° dextroversion (neutral zone) (A) ; fast phase to the left in primary position (B); and fast phase to the left in 30° levoversion (C).

Fig 6.—Case 3, Preoperative (top) postoperative limitation of adduction.

5. —Case 3, After surgery, fast phase to right in 30° dextroversion (A); decrease of nystagmus in primary position (B); and fast phase to the left in 30° levoversion (C).

Fig

the

and

normal head posture because the im¬ provement of the nystagmus in prima¬ ry position relative to lateral gaze positions no longer forced the patient to assume a compensatory face turn to gain optimal visual acuity. This is of special interest because, in our experi¬ ence, medical treatment of this condi¬ tion with baclofen1" is rarely tolerated for a prolonged period on account of the side effects of this medication. Retroequatorial recession of an ex-

postoperative (bottom) dextroversion and levoversion. Note only moderate

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traocular muscle can be expected to produce considerable slack of that muscle. Only long-term follow-up of patients thus treated will determine whether this slack causes secondary contracture and subsequent tightening of the muscles and, thus, recurrence of the nystagmus. However, it is reason¬ able to predict that provided the innervational impulses causing the nystag¬ mus remain the same, even a tight muscle will be incapable of exerting its preoperative rotational effect once the insertion has been positioned behind the equator of the globe. One may wonder why unconvention¬ ally large recessions of normally acting rectus muscles do not cause severe limitation of ocular motility. Such limi¬ tations must certainly be expected when recessing a single rectus muscle that far posteriorly because this will disturb the equilibrium of muscle forces between agonist and antagonist in favor of the unoperated antagonist. However, it appears from this study that simultaneous recession of two an¬ tagonistic rectus muscles does not up¬ set this balance, that excessively large recessions are tolerated wrell, and that

minimal (case 1) and moderate (case 3)

postoperative limitations of ocular motility were without functional significance. Because of the common experience

in strabismus surgery that a recession of the medial rectus is more effective than a recession of the lateral rectus per millimeter of surgery, we did an¬ ticipate a consecutive exodeviation in our patients. Surprisingly, this did not occur. Patients 1 and 3 remained orthotropic after surgery and the preex¬ isting exotropia in case 2 did not in¬ crease after the operation. Thus, the traditional view, according to which a given amount of recession of the medi¬ al rectus muscle is more effective than a recession of the lateral rectus, does not apply when both muscles are si¬ multaneously recessed. If congenital nystagmus is associated with strabis¬ mus, it may be prudent to perform strabismus surgery on the nonfixating eye and to limit nystagmus surgery to the fixating eye.1" Finally, one may ask whether uncon¬ ventionally large recessions of both horizontal rectus muscles cause some degree of exophthalmos with widening

of the lid fissures. Although preoper¬ ative and postoperative exophthalmometric data were not collected in our patients, there was no cosmetically

appreciable postoperative protrusion of the globe in the patients under study (Fig 6). The results reported in this study

must be considered

preliminary since long-term follow-up data are avail¬ able. The possibility of a future reoper-

no

the horizontal rectus muscle and the surgical manipulation of muscles recessed that far may pose problems for the less ation

on

cannot be excluded

experienced surgeon. Nevertheless, initial experiences with this proce¬ dure in patients with congenital nys¬

our

tagmus who desire relief from

an

embarrassing cosmetic handicap are encouraging, and there may be addi¬ tional indications for the surgery, such as acquired nystagmus with

oscillopsia.

This study was supported in part by grant EY 07001 from the National Institutes of Health and by the National Children's Eye Care Foundation, Washington, DC.

References 1. Colburn JE. Fixation of the external rectus muscle in nystagmus and paralysis. Am J Ophthalmol. 1906;23:85-88. 2. Friede R. Zur operativen Behandlung des Nystagmus gravis nebst Bemerkungen zur Extraktion der kongenitalen Kataract. Klin Monatsbl

Augenheilkd. 1956;128:451-455. 3. Blatt N. Kreuzung der geraden Augenmuskeln als Methode der Nystagmusoperation. Ber

Ophthalmol Ges. 1961;63:393-403. Keeney AH, Roseman E. Acquired, vertical illusory movements of the environment. Am J Ophthalmol. 1966;61:1188-1191. 5. Arruga A. Posterior suture of rectus muscles in retinal detachment with nystagmus: a preliminary report. J Pediatr Ophthalmol Strabismus. Deutsch 4.

1974;11:36-37.

6. M\l=u"\hlendyckH. Compensation mechanisms and treatment in nystagmus patients with albinism or congenital cataract. Presented at the 6th Congress of the International Strabismological Association; March 11-16,1990; Queensland, Australia. 7. C\l=u"\ppersC. Probleme der operativen Therapie des okul\l=a"\renNystagmus. Klin Mouatsbl Au-

genheilkd. 1971;159:145-157. 8. Kaufmann H, Kolling G. Operative Therapie bei Nystagmuspatienten mit Binokularfunktionen mit und ohne Kopfzwangshaltung. Ber Deutsch Ophthalmol Ges. 1981;78:815-819. 9. B\l=e'\rardPV, Qu\l=e'\r\l=e'\MA, Roth A, Spielmann A, Wolliez M. Chirurgie des strabismes. Paris, France: Masson; 1984:430. 10. Bietti GB. Note di tecnica chirurgica oftalmologica. Boll d'oculist. 1956;35:642-656.

GB, Bagolini B. Traitement m\l=e'\dicodu nystagmus. L'Annee Ther Clin Oph-

11. Bietti

chirurgical

talmol. 1960;11:268-293. 12. de Brown E Limon, Bernadeli J Corvera. Metodo debilitante para el tratamiento del Nistagmus. Rev Mex Oftalm Marzo-Abril. 1989;63:65-67. 13. Von Noorden GK. Binocular Vision and Ocular Motility: Theory and Management of Strabismus. 4th ed. St Louis, Mo: CV Mosby Co; 1990. 14. Von Noorden GK, Munoz M, Wong SY. Compensatory mechanisms in congenital nystagmus. Am J Ophthalmol. 1987;104:387-397. 15. Yee RD, Baloh RW, Honrubia V. Effect of baclofen on congenital nystagmus. In: Lennerstrand G, Zee DS, Keller EL, eds. Functional Basis of Ocular Motility Disorders. Elmsford, NY: Pergamon Press Inc; 1982:151.

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