Year : 2002 | Volume
: 50 | Issue : 2 | Page : 97--101
Primary inferior oblique overaction-management by inferior oblique recession.
Kamlesh, S Dadeya, V Kohli, S Fatima
Guru Nanak Eye Centre, Maulana Azad Medical College, New Delhi, India
Guru Nanak Eye Centre, Maulana Azad Medical College, New Delhi
PURPOSE: To evaluate the effect of 10 mm inferior oblique recession in horizontal strabismus with V pattern and primary inferior oblique overaction. METHODS: Ten patients of V esotropia and exotropia with primary inferior oblique overaction underwent 10 mm inferior oblique recession by the methods described by Park and Stallard. Pre- and postoperative V pattern, inferior oblique overaction and binocularity were assessed. Patients were followed up for 3 months. RESULTS: The mean preoperative V pattern was 38.3 PD and the mean inferior oblique overaction was 22 PD. After surgery the mean correction of the V pattern was 26.9 PD and the mean residual V pattern was 11.4 PD. None of the patients had inferior oblique overaction postoperatively. 70% of the patients showed improvement in binocularity. CONCLUSION: 10 mm Inferior oblique recession by the described technique is a simple, safe and effective method for the cosmetic and functional treatment of horizontal deviation and V pattern with primary inferior oblique overaction.
|How to cite this article:|
Kamlesh, Dadeya S, Kohli V, Fatima S. Primary inferior oblique overaction-management by inferior oblique recession. Indian J Ophthalmol 2002;50:97-101
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Kamlesh, Dadeya S, Kohli V, Fatima S. Primary inferior oblique overaction-management by inferior oblique recession. Indian J Ophthalmol [serial online] 2002 [cited 2013 May 21 ];50:97-101
Available from: http://www.ijo.in/text.asp?2002/50/2/97/14792
Recognition and specific management of A and V patterns has become a very important factor in strabismology in the past five decades. For the purposes of management, patients of V phenomenon can be broadly divided into two groups: patients with V phenomenon but with normal obliques (group A); and patients with V phenomenon but with the inferior oblique(s) overaction (group B). This inferior oblique overaction (IOOA) may be either primary or it may be secondary to ipsilateral superior oblique palsy or contralateral superior rectus palsy.
Patients in group B are usually managed by inferior oblique weakening with or without horizontal muscle surgery. This basic principle was established by the American Academy of Ophthalmology Panel, 1964 and the reports of Gobin, and Park. These have received wide consensus among strabismologists. Yet there are very few studies, that state the correction of the V pattern in absolute terms following inferior oblique weakening surgery, factors that have a bearing on the surgical outcomes, and the frequency of functional cure. Most published studies have evaluated the correction of the inferior oblique overaction or correction of hypertropia in primary position. The outcome is expressed as reduction, improvement or elimination of V-pattern following surgery and is further substantiated with photographic documentation. Secondly, many of the studies that have not stated the correction of the V pattern in absolute terms have included cases with normal superior oblique and cases with paralytic superior oblique in the same study population. Yet these two groups differ in terms of their aetiopathogenesis and behave differently in many surgical interventions.
We therefore conducted this study in order to evaluate the effect of inferior oblique weakening on V phenomenon with IOOA but with normal superior obliques. The study also determined the extent of V-pattern correction after the "culprit" overacting inferior oblique has been surgically normalised. Our aim was not to compare the different surgical procedures for inferior oblique weakening but to present the specific results produced by one procedure consistently applied to all patients, i.e., 10-mm inferior oblique recession by a method based on Park's 10 mm recession and the method described by Stallard.
Materials and Methods
Ten patients of horizontal strabismus with V phenomenon and IOOA but no extraocular muscle palsy were included in the study. All of them underwent 10 mm inferior oblique recession with or without horizontal muscle surgery. Of the 10 patients, 6 had V exotropia (Group 1) and 4 patients had V esotropia (Group 2).
The preoperative evaluation of the patients included a comprehensive history, vision and refraction, fundus examination, measurement of the deviation by prism bar cover test in the primary gaze, 25° upgaze and 25° downgaze both at near (33 cm) and distance (6 metres) wearing the refractive correction and looking at an accommodative target. Inferior oblique overaction was measured in adduction in all patents, so also the status of binocularity [Table:1]. The IOOA was determined by measuring the hypertropia of the adducting eye using vertical prisms during extreme dextroversion and levoversion. The IOOA was graded as trace: 0-9 PD, Grade 1:10-19 PD, Grade 2:20-29 PD, Grade 3:30-39 PD, Grade 4:40 and above PD. Only patients with IOOA of 10 PD or more were included in this study. This was based on our personal experience, that horizontal muscle surgery above done corrects V pattern in cases with IOOA less than 10PD and associated horizontal deviation.
During surgery the inferior oblique was severed from its insertion 3 mm from the globe. The anterior end of the inferior oblique was sutured 3 mm inferior and 2 mm lateral to the lateral end of the inferior rectus insertion (Scheie Park's point, 1971) and the posterior end of the inferior oblique was sutured 7 mm lateral and 7 mm inferior to the inferior end of the lateral rectus insertion (as described by Stallard, 1986). This method ensured that there was no bunching of the muscle and the muscle remained in its plane of action. When needed, this surgery was combined with the appropriate horizontal muscle surgery either in the same sitting or at a second sitting. All the surgeries were done under the operating microscope in order to ensure neatness and precision. A follow-up of at least 3 months was done in all cases, with careful assessment on the lines of the preoperative examination. We then evaluated our results in terms of the correction of IOOA, the correction of the V pattern, the factors that affect the surgical outcome, the functional cure obtained and complications, if any. Fishers exact test was used to test association between horizontal deviation and residual V pattern.
The mean age of the patients in our series was 12.15 years (range 4-25 years). Patients with Vesotropia appeared to present earlier than V exotropia: the mean age was 8.37 years for V esotropia and 14.67 years for V exotropia. To simplify data evaluation, the patients were divided into 2 groups. Group I included patients with V exotropia (Cases No. 1-6), and Group II included patients with V esotropia (Cases No. 7-10). The mean preoperative V pattern at near was 38.3±13.81 PD (range 15 to 62 PD) and at distance, was 34.3±11.87 PD. In V exotropia it was 46.33±9.18 PD at near and 40.83±6.85 PD at distance, (range 34 to 62 PD). In V esotropia it was 26.25±10.44 PD at near and 24.5±11.5 PD at distance (range 15 to 38 PD). [Table:1].
The mean correction of the V pattern was 26.9±13.39 PD at near and 23.1±11.5 PD at distance. In V exotropia it was 26.9±13.39 PD at near and 25.83±7.25 PD at distance. In V esotropia it was 19.75±11.59 PD at near and 19.0±12.94 PD at distance. Following surgery 68.98% of the V pattern was corrected for near and 67.74% of the V pattern for distance [Table:2].
Eight of our patients had unilateral IOOA and two patients had bilateral IOOA Forced duction test for obliques was negative in all cases. Complete normalisation of the overacting inferior oblique was seen in 9 of 10 cases postoperatively and only one patient had a postoperative underaction of 2 PD The important finding in our series was that the varied amount of IOOA disappeared after same amount of surgery. In no case was a residual overaction seen. In absolute terms, the correction of the inferior oblique overaction was on an average 21.83 PD; it was 23.83 PD in cases with V exotropia and 17.75 PD in cases with V esotropia. [Table:2].
The co-relation between the postoperative horizontal alignment and the residual V pattern was studied. As can be seen from [Table:3], of the 6 patients who were orthophoric ±10 PD postoperatively, 5 had a residual V pattern of 0-10 PD and one patient had a residual V pattern of 11-20 PD. Two patients had a residual under-correction of 11-20 PD. Of these one had a residual V pattern of 21-30 PD. When chi-square with Yates correction was applied no significant correlation was found between postoperative alignment and residual V pattern (p = 0.33).
The correlation between the postoperative horizontal alignment and the postoperative binocularity was also studied [Table:4]. Patient no.1 in our series had a V pattern of 43 PD with deviation of 55 PD in primary position. This patient had only right IOOA of 28 PD. This patient underwent inferior oblique recession along with lateral rectus recession in the right eye. This patient had 45 PD of horizontal deviation along with 30 PD of residual V pattern, which was completely normalised after second surgery on horizontal muscles along with upward shifting of lateral rectus and downward shifting of medial rectus.
In our study, we found that inferior oblique recession is an effective way to manage patients with V phenomenon with primary inferior oblique overaction. A mean correction of 26.9 PD in the V pattern at near and 23.1 PD at distance with a mean residual V pattern of 11.4 PD at near and 11.2 PD at distance may be expected by the described method of inferior oblique recession.
The greater the preoperative deviation, the greater is the correction obtained. Overall, 68.96% of the correction of the V pattern at near and 67.75% of the V pattern at distance can be expected to occur by this surgery. Thus though the entire V pattern is not eliminated by this surgery it leads to cosmetically and functionally acceptable results in most cases [Figure:1]a and [Figure:1]b. In our series 70% of the patients had a residual V pattern of just 0-10 PD, 10% had a residual V pattern of 11-20 PD and 20% had residual V pattern of 21-30 PD. Complete normalisation of the overacting inferior oblique was seen in 9 of 10 patients postoperatively and only one patient had a postoperative underaction of 2 PD. Residual overaction was not seen in any eye.
It is important here to point out that same amount of recession caused total disappearance of IOOA in all patients. In absolute terms, the correction of the IOOA was on an average 21.83 PD; it was 23.83 PD in cases with V exotropia and 19.83 PD in cases with V esotropia. This residual V pattern was present despite the fact that the IOOA had been completely eliminated by the surgery in all cases.
The results obtained by other surgeons by their inferior oblique weakening procedures vary. Burian et al reported an average change of 15.4 PD in V esotropia
and an average change of 11.47 PD in V exotropia with a residual V of 9.13 PD and 14.07 PD respectively: Prakash et al obtained a correction of 14.5 PD in V esotropia but a much greater correction of 24.0 PD when they combined inferior oblique recession with vertical transposition of the horizontal muscles. In the series of Costenbader and Kertey, Fink's 8 mm recession led to an average correction of 2.2U of IOOA with a residual overaction of 0.4U in 90% of his cases, no change in 8% and a residual underaction of 1 U in 2% of the patients (IU=1-9 PD, 2 U-10-19 PD, 3U>20 PD). In the series of Cooper and Sondall, inferior oblique recession led to a correction of 11.96 PD with a residual overaction of 3.11 PD. Anteropositioning of the inferior oblique is seen to lead to a normal inferior oblique in 50% of the cases of V esotropia, and mild residual overaction in 38% of the cases. Ziffer reported a correction of 1.25 U (in an arbitrary scale of 0 and +4 for IOOA). Prakash, et al obtained a correction of 12.76±3.3 PD by Park's 10mm recession, 18.80±6.5 PD by Elliot and Nankin's anteropositioning and 12.76±3.3 PD by pure anteropositioning. But their series included patients of both primary and secondary IOOA and hence direct comparisons cannot be made between our results and theirs. The success rate of various inferior oblique weakening procedures is given in [Table:5]. Various authors have reported a variety of complications like residual overaction, recurrence, underaction, postoperative hypotropia, diplopia, adherence syndrome and internal ophthalmoplegia.,,, However, we did not see any complication except mild underaction of IOOA (2PD) in one case.
The factors that may influence the postoperative residual V pattern were considered. Early age of surgery and short duration of strabismus were seen to increase the chances of developing a small residual V pattern only but the relationship was not very definite. A more definite relationship was found between the postoperative horizontal alignment in the primary gaze and the residual V pattern. The closer to orthophoria the patient was, the lesser was the chance of having a large residual V pattern. But this was not statistically significant. Good results may be expected in terms of the change in the binocular status of the patients if the patient achieves good horizontal alignment in primary gaze. It was seen that early age at surgery and a short duration of strabismus favoured the development of binocularity though a very definite correlation could not be found. But a definite positive correlation was found between the postoperative horizontal alignment and the binocularity. If the patient was close to orthophoria, he had a high chance of developing binocularity, and if he had a large horizontal deviation left, his chances of attaining binocularity were poor Based on our results, we conclude that 10 mm inferior oblique recession by our technique is a safe, simple and effective method for treatment of horizontal deviation with V pattern with primary inferior oblique overaction.
|1||Gobin MH. Anteroposition of inferior oblique muscle in V esotropia. Ophthalmsologica 1964;148:325-41.|
|2||Park NM. Monocular vertical displacement of the horizontal rectus muscle in the A and V patterns. Am J Ophthalmol 1972;73:107-22.|
|3||Ropar MJ. Eds. In Stallard's eye surgry. Bristol: John Wright & Sons Lt. 1987. pp360-67.|
|4||Apt L, Call MB. Inferior oblique recession. Am J Ophthalmol 1978;85:95-100.|
|5||Burian H. Symposium: The A and V patterns in strabismus treatment. Trans. Am Acad Ophthalmol Otolayng. 1964;68:375-80.|
|6||Prakash P, Menon V Nath J. Surgical management of A and V pattern. Indian J Ophthalmol 1983;31:463-65.|
|7||Costenbader FD, Kertey E. Relaxing procedure of the inferior oblique. Am J Ophthalmol 1964;57:276-80.|
|8||Cooper EL, Sondall GS. Recession versus free mytomy at the insertion of the inferior oblique muscle. J Pediatr Ophthalmol 1969;6:6-10.|
|9||Ziffer AJ, Isenberg SJ, Elliott RL, Leonard APT. The effect of anterior transposition of the inferior oblique muscle. Am J Ophthalmol 1993;116:224-27.|
|10||Prakash P, Gupta A, Sharma P. Pure anteropositioning of inferior oblique; a selective weakening procedure. Acta Ophthalmol 1994;72:373-75.|
|11||Elliot NS. Anterior transposition of inferior oblique. J. Pediatr Ophthalmol Strabismus. 981;18:35-40.|