Weakening Procedure Research Articles

Superior oblique tendon expansion in the management of superior oblique dysfunction.

Traditional superior oblique weakening procedures may be unpredictable and lead to superior oblique underaction. The use of 240 retinal band as a spacer to lengthen the superior oblique tendon has been proposed as a more controlled approach than superior oblique tenotomy and related procedures. The use of this technique is reported in a patient with diplopia following an orbital floor blow out fracture, and in a child with Brown's superior oblique tendon sheath syndrome.

Treatment of alphabetic "V" syndromes

Described in the early fifties, V phenomenon remains a controversial subject in respect to its etiopathogeny. Several theories have been proposed dealing to specific surgical treatments. According to the "oblique" theory, we have been performing a bilateral inferior oblique muscle weakening procedure alone or combined with horizontal muscle surgery in our patients presenting horizontal squint associated with a "V" phenomenon. Since 1984, among the 103 patients presenting with a "V" phenomenon, we have been able to analyze 55 cases (40 "V" esotropias and 15 "V" exotropias) who underwent 3 different surgical protocols; 1) bilateral inferior oblique (IO) muscles weakening procedure combined with conventional horizontal surgery, 2) bilateral IO weakening procedure combined with posterior fixation of Med. Recti (Faden operation) in esotropias only, or 3) bilateral inferior oblique muscles weakening alone. All groups were comparable in respect with there pre-surgical "V" pattern. No statistical significant difference in reduction of the "V" pattern could be demonstrated in the different treatment protocols. "V" esotropias showed a mean 16.3 delta diopter reduction +/- 2.2 SEM in treatment number 1; 19.8 +/- 2.1 in treatment 2. Reduction was only 10.7 +/- 3.3 in group with third treatment. "V" exotropias reduction were: 15.4 delta diopter +/- 1.6 in the combined surgical procedure compared to 18.3 +/- 4.8 in IO weakening alone. No dose-effect relationship could be clearly demonstrated in measured IO weakening procedure. IO weakening procedure is effective in reducing "V" pattern. This effect is enhanced if associated with an horizontal muscle surgery which reduces the horizontal deviation especially in in V esotropias. We prefer Fink's procedure to simple myotomy since its allows a measurable and reversible IO weakening.

Surgical techniques of strabismus.

Improvements in the management of strabismus are largely dependent on making the specific diagnosis and differentiating patterns of strabismus. This finding is especially true in the management of superior oblique paresis because there are various types. Recent observation suggests that superior oblique paresis may be associated with a lax superior oblique tendon and that the cause of the paresis is not always neurogenic. Some authorities have suggested using the traction test of the superior oblique to determine whether the superior oblique tendon is lax. If it is lax, the treatment of choice would be a tightening procedure of the superior oblique such as the superior oblique tuck. Adjustable-suture strabismus surgery has reduced the incidence of repeat operations; however, adapting the procedure to the fornix incision has been difficult. The use of a scleral traction suture that retracts the conjunctiva to expose the muscle suture area has been useful for fornix surgery. The rectus muscles supply circulation to the anterior segment via the anterior ciliary vessels, which are routinely interrupted during strabismus surgery. Various procedures have recently been described to preserve the anterior ciliary vessels, and these procedures will be useful in patients who are predisposed to anterior segment ischemia. In the 1950s, inferior oblique weakening procedures were deemed dangerous and unpredictable. Recent advances in the understanding of inferior oblique physiology and fascial relationships have inspired the development of a new inferior oblique weakening strategy--the anteriorization procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of torsional muscle dysfunction and surgery on eye position under general anesthesia.

Under general anesthesia, normal eyes exhibit 2.0 degrees to 2.5 degrees of extorsion. To investigate the effect of torsional muscle dysfunction and surgery on eye position under general anesthesia, we measured the torsional change before and after torsional muscle surgery in 26 eyes of 18 patients with clinical torsional muscle dysfunction. Under general anesthesia, compared with normals, eyes with preoperative intorter overaction or extorter underaction demonstrated a significant intorsional change (P < .01). However, eyes with intorter underaction or extorter overaction did not demonstrate a significant extorsional change. Postoperatively, while patients remained under general anesthesia, intorter weakening procedures produced measurable extorsion while intorter strengthening procedures and extorter weakening procedures produced measurable intorsion. Superior oblique tenotomy produced a greater net torsional change than inferior oblique weakening surgery (P < .01). Under general anesthesia, eyes with preoperative torsional muscle dysfunction exhibit torsion in the direction consistent with the dysfunction. After surgery on the torsional muscles, a measurable torsional effect can be demonstrated while the patient is still under general anesthesia.

Superior oblique tuck surgery in the management of superior oblique palsies.

Three hundred and twenty-four patients with superior oblique muscle palsies required surgery over a 15-year period. Forty-four patients underwent superior oblique tuck surgery. Fifteen patients had unilateral and six bilateral tucks alone. Seventeen had unilateral tucks and three bilateral tucks in conjunction with other extraocular muscle surgery. Three had unilateral tucks with a contralateral Harada-Ito procedure. The best results were obtained with isolated superior oblique tucks and tucks in conjunction with a contralateral inferior rectus muscle recession or an ipsilateral inferior oblique muscle weakening procedure. The mean vertical correction following isolated, unilateral surgery was 3.6 prism diopters (range, 0 to 11 delta) in primary gaze and 15.3 delta (range, 0 to 40 delta) in the field of maximum deviation. The mean eso correction in downgaze with bilateral superior oblique tucks was 15.2 delta (range, 10 to 21 delta). There was no statistically significant correlation between the size of the tuck and the amount of deviation corrected. Some degree of postoperative Brown syndrome was seen in all patients, but became less marked with time and in no patient was it severe enough to require reversal of the tuck. In only four patients was there a significant lessening of the effect of the procedure with time. The results show that the superior oblique tuck procedure is an effective operation. In patients with unilateral muscle palsies, 64.3% with an abnormal head posture, 37.5% with diplopia, and 100% with both an abnormal head posture and diplopia achieved an excellent result. In patients with bilateral muscle palsies, 50% with an abnormal head posture and 66% with both an abnormal head posture and diplopia achieved an excellent result.

Traction Testing in Superior Oblique Palsy

This report describes the use of superior oblique traction testing in the evaluation of superior oblique palsy. Four consecutive children presenting with signs and symptoms of superior oblique palsy were found to have markedly abnormal tendon laxity with traction testing. Surgical exploration revealed anomalies including three with elongated lax tendons, one of which had an anomalous insertion, and one absent tendon. This tendon laxity is not typically found in acquired superior oblique palsy. It is proposed that, in addition to the well known neurogenic paresis/paralysis, a second type of "palsy" due to anatomic abnormalities of the tendon may exist and be responsible for a number of congenital superior oblique palsies. The mechanical disadvantage of these markedly long tendons may explain why inferior oblique weakening procedures alone frequently fail to correct head tilts due to superior oblique palsy in infancy.

Response of Coexisting Underacting Superior Oblique and Overacting Inferior Oblique Muscles to Inferior Oblique Weakening

One hundred twenty-six eyes with inferior oblique overaction and coexisting superior oblique underaction were retrospectively studied pre- and postoperatively. The data show that weakening the inferior oblique corrected the underaction of the superior oblique, and that overcorrection of the underacting superior oblique was unusual. Eyes were selected for study if superior oblique underaction coexisted with inferior oblique overaction preoperatively. The operation chosen for the inferior oblique in every case was determined by the quantity of inferior oblique overaction and whether prior surgery on the inferior oblique had been performed. A denervation and extirpation was the final inferior oblique weakening procedure in all except three of these eyes. Congenital or acquired superior oblique palsy cases were not included in this study. To eliminate eyes with superior oblique palsy, we excluded any patient with a history of serious head trauma; a vertical deviation in the primary position greater than 5 prism diopters except if caused by dissociated vertical deviation; the complaint of torsional diplopia controlled by an anomalous head posture; or a positive Bielschowsky head tilt test. The mean preoperative superior oblique action was -2.4 on a scale of 0 to 4, and this corrected to a mean postoperative action of -0.2, (P less than .001). This was accompanied by a change in the mean inferior oblique action of +3.8 to -0.2, (P less than .001). These same results were found regardless of the preoperative action of either the inferior or superior oblique. With regard to the postoperative superior oblique action, 22 cases were undercorrected, 2 were overcorrected, and 102 were normal.

Congenital superior oblique palsy in infants.

A retrospective review of 20 cases of infants with congenital superior oblique palsy showed that all cases had been diagnosed and treated surgically before the patient was 2 years old. Single inferior oblique weakening procedures, single superior oblique tucks, and combined inferior oblique weakening procedures and superior oblique tucks were performed as the initial surgical procedures. Best results were obtained with the two-muscle procedure. The presence of preoperative primary position hypertropia correlated significantly with failure of single inferior oblique weakening to eliminate the signs of superior oblique palsy.

Inferior oblique surgery. Experience at the Mayo Clinic from 1960 to 1981.

Three hundred thirty-seven patients underwent inferior oblique disinsertions at the Mayo Clinic Rochester, Minn, from 1960 to 1981. Versions and hyperdeviations in the primary position were recorded preoperatively and postoperatively. The criteria of a successful result were (1) correction of diplopia, (2) correction of hyperdeviation in the field of action of the inferior oblique, and (3) correction of versions in adduction. Clinical failure was reflected in persistence of hyperdeviation in primary gaze and persistence of overaction of the inferior oblique muscle in adduction. A successful result was found in 88% of primary inferior oblique disinsertions. For secondary inferior oblique overaction, a successful result was found in 72% of patients. We have found that inferior oblique disinsertion is a safe, fast, reliable, and effective weakening procedure with good results.

Denervation and Extirpation of the Inferior Oblique: An Improved Weakening Procedure for Marked Overaction

Parks1 demonstrated that recession was more effective than myectomy at insertion or origin, or disinsertion for eliminating inferior oblique overaction. This study simultaneously compares an improved procedure, an extirpation of the inferior oblique that involves denervating it, to 14 mm recession in a prospective, consecutive series of 16 patients with symmetrical 4+ overaction of the inferior obliques; one technique (extirpation) performed on the right eye, and the other (14 mm recession) on the left. Mean duration of follow-up was 20.8 months (range 17 to 34 months). Extirpation resulted in 100% normal action, without residual overaction or underaction. Recession, however, resulted in 1+ to 3+ residual overaction in 12 cases (75%) and 4+ overaction requiring reoperation in two eyes (13%). It appears that extirpation of the inferior oblique is far superior to 14 mm recession for treatment of marked overaction of the inferior oblique.

The effect of superior oblique weakening procedures on primary position horizontal alignment.

The effect of superior oblique weakening procedures on primary position horizontal alignment.

Late Results of Superior Oblique Muscle Tenotomy in True Brown's Syndrome

We re-assessed nine patients (aged 2 to 28 years) in whom true Brown's syndrome had been diagnosed and superior oblique muscle tenotomy performed. The postoperative period ranged from three to 12 years. The final results were divided into three groups: (1) Patients with partial residual Brown's syndrome postoperatively who gradually improved spontaneously over several years, with one exception. (2) Patients who had minimal or moderate superior oblique muscle paresis, secondary overaction of the homolateral inferior oblique muscle, and excellent binocular single vision postoperatively who improved spontaneously. In Groups 1 and 2, the study showed that the long-term results are better than those immediately after surgery, and the surgeon should not be too hasty in reoperating. (3) Patients with marked superior oblique muscle paresis and secondary homolateral inferior oblique muscle overaction postoperatively did not improve spontaneously and required a weakening procedure on the homolateral inferior oblique muscle.

Inferior oblique weakening procedures. Effect on primary position horizontal alignment.

Fifty patients who only had bilateral inferior oblique weakening procedures were retrospectively analyzed to determine the third month postoperative horizontal alignment change produced in the primary position. No significant horizontal change occurred in 84% of the patients and, in those who manifested a change, it was never greater than 8Δ. Six percent manifested an esophoria shift of more than 3Δ and 10% had an exophoria shift of more than 3Δ. It was concluded that the surgeon should not fear producing a postoperative esotropia by weakening the inferior oblique muscles in patients who preoperatively have straight eyes in the primary position.

Marginal myotomy.

<h3>To the Editor.</h3> —Dr. John Kennedy recommends the marginal myotomy, as described by Morgan, as the initial weakening procedure of the medial recti for esotropia in infants because the recession procedure is difficult in the infant, and buried sutures often cause excessive reaction and consequent limitation of abduction due to scar formation (Arch Ophthal<b>84</b>:625-626, 1970). I have performed recession of the medial recti in several hundred infants over the past 23 years and find the procedure to be no more difficult in infants than adults provided small instrumentation and sutures are used. Nor am I aware of excessive reaction caused by the buried sutures with consequent limitation of abduction due to scar formation. Most disturbing to me is Dr. Kennedy's advice to perform a crippling procedure on a muscle as the initial surgery for strabismus, The primary objective of the strabismus surgeon should be to manipulate the