Simultaneous surgical correction of dissociated vertical deviation, superior oblique overaction and A-pattern with associated horizontal strabismus: A case series.

Sir,

In patients with dissociated vertical deviation (DVD), laterality, symmetry, and comitance are vital factors for deciding the appropriate surgical management; associated superior oblique over action (SOOA), if present, results in incomitant DVD and an A-pattern.[12] Superior rectus recession with posterior tenectomy of superior oblique (PTSO) has been proven to give good results in DVD with A-pattern with SOOA.[3] When this triad is also associated with a large angle primary position horizontal strabismus, the surgical management becomes challenging. We hereby report our results in- patients who underwent bilateral weakening of the superior rectus, superior oblique, and horizontal muscle recession for associated horizontal deviation in the primary position as a single stage procedure.

A retrospective review of the file records of all patients of DVD with SOOA with A-pattern horizontal strabismus who underwent bilateral superior rectus recession with PTSO with horizontal muscle recession, over a period of 3 years (January 2008-December 2010) at Dr. Shroff’s Charity Eye Hospital was undertaken. Approval for the same was obtained from the Institute review board. The inclusion criteria were bilateral incomitant DVD with SOOA (DVD greater in abduction and least or not present in adduction), A-pattern ≥ 10 PD and associated primary position horizontal deviation ≥ 20 PD. Those patients with previous surgery on vertical/oblique muscle and with a follow- up of less than 3 months were excluded. Out of 14 files reviewed, 4 patients who fulfilled all the criteria were finally included for analysis.

Pre-operative patient details and orthoptic data, details of the surgery undertaken and post-operative results were collected from the records, details of which are summarized in Table 1. All patients had undergone bilateral superior rectus recession with PTSO along with horizontal muscle recession as a single stage procedure. With this combined approach, A-pattern decreased from 26.25 ± 6.29 PD (range 20–35 PD) pre-operatively to 8 ± 2.94 PD (range 5–12 PD) postoperatively. The average collapse in the pattern was 18.25 ± 7.41 PD (range 12-28 PD). DVD in the primary position (average of both eyes) decreased from 11.37 ± 4.75 (range 6–20 PD) to 5.5 ± 2. (range 2–8 PD) while DVD asymmetry reduced from 5.25 ± 2.5 (range 2–4 PD) to 3 ± 0.82 (range 2–8 PD).

Table 1

Pre-operative and post-operative details of four patients in our series

The triad of A-pattern exotropia, bilateral SOOA and DVD had been first reported as early as 1966, though the associated incomitance had not been mentioned. The usual approach for such cases is to perform a 2 staged procedure; DVD and A-pattern in the first stage and second stage for horizontal deviation. Mc Call and Rosenbaum in 1991 for the first time described surgical weakening of both superior rectus and superior oblique for incomitant DVD.[4] Velez in their study also recommended that patients with A-pattern measuring 12 PD to 20 PD require superior oblique weakening in combination with superior rectus recession.[3] We found good surgical results in our series of patients who underwent single step combined surgery for superior recti, superior oblique and horizontal recti in patients with this triad as well as associated horizontal strabismus These results are in accordance that published by Velez et al. in their 14 patients with DVD with A-pattern of 12–20 PD.

To conclude, simultaneous weakening of the superior rectus, superior oblique and horizontal recti as a single stage procedure gives good surgical results and correlates well with pre-operative magnitude of DVD and A-pattern.