In the current study, we report the surgical outcomes of different surgical methods based on the extent of patients’ manifestations; the degree of A-pattern, SOOA, and DVD. Taking into consideration, the fundus photography intorsion may support the significance of superior oblique overaction and aid in considering weakening of the superior oblique muscle, for more predictable and better outcomes. The DVD of the patients in group A was more than 15 PD, and the A-pattern was quite small without significant SOOA; hence, the surgical planning was mainly aimed at resolving the DVD by combining superior rectus recession with horizontal alignment, without superior oblique lengthening. However, in group B, the A-pattern was quite large at ≥ 15PD with significant SOOA, but the DVD was ≤ 10PD; the surgical planning was aimed at reducing the A-pattern and SOOA by combining superior oblique lengthening with horizontal alignment. For patients with DVD more than 15PD and significant SOOA that caused obvious intorsion with a large A-pattern, i.e., patients in group C, horizontal correction combined with SO muscle lengthening was performed. In those cases, the DVD was still obvious postoperatively; hence, bilateral superior rectus recession was performed after 3 months or more to correct the residual DVD.
Velez et al. showed that bilateral superior rectus muscle recession can correct small amounts of A-pattern; larger amounts of A-pattern required additional SO weakening . Ganesh et al. reported that small to moderate A patterns measuring less than 20PD may respond well to superior rectus weakening with SO weakening . Ha et al. suggested that horizontal muscle surgery alone should be performed when the degree of SOOA and the A-pattern deviation are minimal . In terms of the A-pattern, our findings were in line with those of prior studies.
For the management of DVD, superior rectus recession is usually the preferred surgical method , while weakening of the SO muscle (tendon lengthening, tenotomy, or tenectomy) is found to be effective in collapsing of the A-pattern . Previous studies have shown good results in correcting the DVD with the A-pattern and SOOA by superior rectus recession with posterior tenectomy of the superior oblique [2,3,4]. In cases of pattern deviations with oblique muscle overaction, oblique muscle weakening may be a suitable option as it decreases the torsion that may contribute to the pattern . A large reduction in intorsion was reported by Wu et al. after the weakening of the SO muscle . In our series, 5 out of 9 patients in group A had a little degree (10–11PD) of DVD after surgery. The incomitance of DVD across horizontal gazes was not taken into account in our investigation. According to McCall et al., superior rectus weakening alone will not be able to resolve the incomitance exhibited when DVD is present, and undercorrection may result . It's possible that, in addition to superior rectus recession, adding superior oblique weakening when DVD is greatest in abduction or inferior oblique anterior transposition when DVD is greatest in adduction would have yielded better results for such patients .
The A-pattern may be associated with SOOA and intorsion, but ocular torsion may not be the primary etiological factor for pattern strabismus . However, whenever there is obvious hyperfunction of the SO muscle and fundus intorsion, the SO muscle should be weakened . This can be achieved by lengthening the SO muscle by non-absorbable sutures, which can partially weaken the function of the SO muscle in different grades . Partial resection of the SO tendon is sometimes used to deal with the rotation effect (anterior part of the tendon) or the vertical effect (posterior part of the tendon) alone. However, in the case of the Helveston triad, the vertical effect (to correct the DVD) and the rotation effect (to correct the A-pattern) should be managed, thereby requiring tenectomy. Moreover, the reduction in the A-pattern obtained after partial resection of the posterior fibers of the SO muscle is less than that obtained by complete resection (tenotomy or tenectomy) . Certain substances have been used to separate the broken ends of the SO muscle, such as Achilles tendon  or a piece of silicon tape , but adding these substances would increase the time and complexity of the surgery. The silicone expanders may cause a severe inflammatory reaction . A direct method is to use a 3–8 mm polyester suture between the broken ends according to the results of the objective forced duction test during the surgery.
Good correlations were found between fundus intorsion, SOOA, and A patterns . Preexisting intorsion in five of eight cases of A-pattern was observed by Sharma et al. These five cases also had SOOA, and the other three cases did not have SOOA and did not show intorsion. This indicates a direct cause–effect relationship between torsion and SOOA . Fundus torsion is described as a marker of SOOA. In the present study, patients with SOOA showed varied degrees of fundus intorsion, particularly when SOOA was obvious. We believe that this should be taken into consideration when planning the surgery.
Among previous studies investigating Helveston syndrome, Ha et al. reported a success rate of 57.1% , whereas Wu et al. reported a success rate of 53.3%, with a small amount of eso-drift in the primary position postoperatively . The overall success rate in the present study was 86.5%, which is higher than those of previous studies; no SO palsy, postoperative inverted V pattern, or induced extorsion were noted.
Nevertheless, there are some limitations in this study. First, the study was retrospective in nature. Second, the follow-up period was relatively short, and the sample size was small. Third, there was no control group, and the surgical techniques employed in the study were variable. A prospective randomized controlled clinical trial is recommended. Patients in group C were managed in two different sessions. Although staging surgery for strabismus involving horizontal and vertical eye movements has been recommended, it may be better if all three surgical methods (lateral rectus recession, superior rectus recession, and superior oblique muscle lengthening) were performed at the same time, as this would reduce the psychological and financial burden on patients.
In conclusion, our experience with the above-mentioned case classification revealed that with such a peculiar combination of ocular motility disturbances, satisfactory outcomes can be achieved in terms of DVD reduction in the primary position, as well as the collapse of the A-pattern and SOOA. The surgical planning of Helveston syndrome should be designed based on the degree of the A-pattern, SOOA, DVD, and the intorsion in fundus photographs, and the appropriate approach should be selected to improve patient satisfaction.