|Year : 2015 | Volume
| Issue : 3 | Page : 250-253
Effect of bilateral superior oblique split lengthening on torsion
Jitendra Jethani1, Kuntal Shah1, Sonal Amin2
1 Department of Pediatric Ophthalmology and Strabismus, Dr. Thakorbhai V Patel Eye Hospital, Vadodara, Gujarat, India
2 Department of Pediatric Ophthalmology, Santram Eye Hospital, Nadiad, Gujarat, India
|Date of Submission||26-Oct-2014|
|Date of Acceptance||24-Mar-2015|
|Date of Web Publication||13-May-2015|
Dr. Jitendra Jethani
Pediatric Ophthalmology and Squint Clinic, Dr. Thakorbhai V Patel Eye Institute, Haribhakti Complex, Salatwada, Vadodara - 390 001, Gujarat
Source of Support: None, Conflict of Interest: None
Introduction: Superior oblique split lengthening (SOSL) is done for weakening of superior oblique. It corrects the superior oblique overaction (SOOA) and A pattern. Its effect on the torsion of the eye is not known. We present our data on the effect of this particular procedure on torsion. Materials and Methods: We did a study of 16 patients (32 eyes) who underwent bilateral SOSL and compared the disc foveal angle (DFA) preoperatively and postoperatively. The split lengthening was done from 4 mm to 7 mm depending upon the overaction of superior oblique. Results: The mean age was 15.3 ± 8.4 years. Mean preoperative DFA in the right eye (RE) was −3.9° and in the left eye (LE) was −2.9°. Mean postoperative DFA in RE was 0.2° and in LE was 0.9°. The mean change in the DFA for RE was 4.1° ± 1.3° and for LE was 3.8° ± 1.2°. All the patients were aligned horizontally within 6 prism diopter and no pattern and no diplopia postoperatively. The A pattern was corrected in all the patient postsurgery. For each mm of surgery, an improvement of 0.8° was seen in the DFA. Conclusion: We report the effect of SOSL on torsion. The SOSL reduces intorsion postsurgery and is, therefore, a valuable procedure in SOOA where both pattern and in torsion needs to be corrected.
Keywords: A pattern, disc foveal angle, intorsion, superior oblique split lengthening
|How to cite this article:|
Jethani J, Shah K, Amin S. Effect of bilateral superior oblique split lengthening on torsion. Indian J Ophthalmol 2015;63:250-3
|How to cite this URL:|
Jethani J, Shah K, Amin S. Effect of bilateral superior oblique split lengthening on torsion. Indian J Ophthalmol [serial online] 2015 [cited 2019 Nov 22];63:250-3. Available from: http://www.ijo.in/text.asp?2015/63/3/250/156929
Superior oblique weakening surgery is performed mainly for superior oblique overaction (SOOA) or brown's syndrome. The various procedures include tenotomy,  tenectomy,  posterior tenotomy,  translation recession,  tendon expander,  spacers,  and split lengthening.  Different Procedures has different effect on the torsion, depression in adduction and A pattern. Superior oblique split lengthening (SOSL) is a relatively uncommon procedure done for weakening of superior oblique. Though the effect of superior oblique weakening has been reported, the effect of this particular procedure on the torsional status of the eye is not known. ,,,, We did a study of 16 patients (32 eyes) who underwent bilateral SOSL and compared the disc foveal angle (DFA) preoperatively and postoperatively.
| Materials and Methods|| |
A total of 16 patients (32 eyes) with bilateral SOOA (+2) or more were taken in the study. All the patients had A pattern preoperatively. Only those patients who underwent SOSL were included in the study. No patient underwent displacement of horizontal muscles. The DFA was measured as described previously both preoperatively and postoperatively at the end of 3 months [Figure 1]a and b. , The surgery was done depending on the SOOA along with the horizontal alignment:
|Figure 1: (a) Preoperative fundus pictures show the disc foveal angle (DFA) of one of the patients. (b) Postoperative fundus pictures of the same patient show improvement in the DFA|
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- For (+2) overaction: 4 mm split lengthening
- For (+3) overaction: 5.5 mm split lengthening
- For (+4) overaction: 7 mm split lengthening.
Surgical technique [Figure 2]
|Figure 2: Various steps of the surgical procedure of split lengthening of superior oblique. The muscle is separated, and the sutures are tied at the desired interval. The muscle is then split and the cut and the ends are anastomosed|
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The superior oblique muscle was approached through a superior fornix conjunctival incision. The superior rectus muscle was isolated first, and the superior oblique was then isolated at the nasal end of the superior rectus muscle under direct visualization. The superior oblique tendon was then spread out on 2 larger muscle hooks for a distance of 8-10 mm. In addition to being spread lengthwise to expose about 10 mm of the tendon, the tendon was also flattened between the hooks to aid in splitting it. One blade of blunt-tip scissors was then pushed through the flattened tendon making every effort to split the tendon in the middle. Using 2 small Stevens muscle hooks, the split was teased and extended as gently as possible in each direction for a distance of requisite amount as decided for the surgery.
After the split had been extended, single armed 6-0 prolene sutures were placed. One was placed through the posterior split segment of the tendon as far distal as possible, and the other was placed in the anterior split segment as far proximal or nasal as possible. Each suture was tied after being passed twice through the tendon. To complete the Z-cut, the posterior tendon was cut with a tenotomy sccisors distal to the preplaced suture, and the anterior piece of the tendon was cut proximal or nasal to the suture. The 2 cut ends were then connected with the needle from each suture being passed through the opposite tendon just behind the preplaced suture. The sutures were then tied producing the desired amount of split Z-tendon lengthening of the superior oblique muscle.
| Results|| |
The mean age was 15.3 ± 8.4 years. The male-female ratio was 6:10. Two patients had esotropia while 14 patients had exotropia [Table 1]. Fourteen (43.7%) eyes were myopic, 10 (31.2%) eyes were hyperopic and the rest was emmetropic. The refractive error was within ± 4 diopters. Six (12 eyes) patients underwent a bilateral 4.0 mm lengthening, 8 eyes underwent a unilateral 4.0 mm, 9 eyes underwent a 5.5 mm, and 3 eyes underwent a 7.0 mm split lengthening of superior oblique.
|Table 1: The preoperative demographic, deviation, and distribution of the patients |
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The mean A pattern preoperatively was 14.8 ± 3.5 prism diopter (PD), which reduced to a mean 1.8 ± 3.5 PD [Table 1] and [Table 2]. Mean preoperative DFA in the right eye (RE) was −3.9° ± 1.9° and in the left eye (LE) was −2.9° ± 1.8°. On measuring the mean postoperative DFA in RE was 0.2° ± 1.7° and in LE was 0.9° ± 1.4°. The mean change in the DFA for RE was 4.1° ± 1.3° and for LE was 3.8° ± 1.2° [Table 3]. For the six cases, which underwent symmetrical 4.0 mm SOSL had a mean DFA change of 3.54° ± 0.78°.
|Table 3: The DFA preoperatively, postoperative and the change in the DFA (postoperative DFA - preoperative DFA) |
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The change in the vertical deviation was minimal and has been mentioned in [Table 1] and [Table 2].
All the patients had SOOA with no restriction and A pattern. All the patients were aligned horizontally within 6 PD and no pattern and no diplopia postoperatively. For each mm of surgery, an improvement of 0.8° was seen in the DFA. And, for each 1° of improvement required at least 1.2 mm of lengthening was required.
| Discussion|| |
The commonly done superior oblique weakening procedures include posterior tenectomy of superior oblique, tendon expanders and sutures (spacers), tenotomy, and SOSL. Only two of the procedures that is spacers (silicone or sutures) and split lengthening of SO could be graded and hence can be controlled depending on the amount of overaction that patient had preoperatively. Bardorf and Baker did suggest that it was a good procedure for weakening of the superior oblique and it has effect on the A pattern too.  In our study, the mean correction the A pattern reduced from a preoperative 14.8 ± 3.5 PD to a postoperative mean of 1.8 ± 3.5 PD. However, the effect of SOSL on torsion has never been studied. Souza-Dias and Uesugui presented a comparison of various techniques of superior oblique weakening and mainly compared its efficacy to correct the A pattern.  No data was reported for torsion and SOSL in his study. Sharma et al., compared the two procedures the spacers spacers (16 eyes) and translational recession (16 eyes) and found a change of 6° and 11.3° change in objective torsion.  Harada evaluated the effects of anterior partial recession of the superior oblique muscle and reported that a 6 mm recession of the superior oblique produced a mean extorsion change of 12°.  Awadein and Gawdat  compared the suture spacers and the silicone band spacers. Though they did compare the torsion, it lacked the assessment on the DFA. It was based on a grading of intorsion (+1, +2, +3, +4) preoperatively and postoperatively and therefore cannot be compared in terms of degrees corrected by the procedure. They, however, found that the two procedures gave a comparable result as far as the torsion was concerned.  Our study (32 eyes) suggests that an average of approximately 4° intorsion is corrected which are comparable with spacer surgery in Sharma et al. study (16 eyes) where they reported a net correction of 6° by the similar objective method.  They did a predetermined fixed 7 mm spacer whereas we had a mixed sample which has predominant of 4.0 mm of lengthening.
| Conclusion|| |
We report the effect of SOSL on torsion. The procedure can be graded depending on the amount of SOOA present preoperatively. The SOSL reduces intorsion postsurgery (0.8°/mm of lengthening) and is, therefore, a valuable procedure in SOOA where both pattern and intorsion need to be corrected. The effect is comparable to the previously reported change in torsion with spacers.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]