Treatment of Vertical Strabismus Association with Thyroid Orbitopathy, Common but Unspoken Complications; increase of Exopthalmos and Scleral Show

Abstract

Purpose: To evaluate the algorithms, results and discuss some unspoken complications of surgical treatments of vertical strabismus and diplopia associated with thyroid orbitopathy. Methods: A retrospective case series, Patients who underwent TO-related vertical strabismus surgery between January 2017 and February 2020 and were followed for at least six months were included in the study. Preoperative activity scores of the cases (The VISA classification), previous treatments; Pulse steroid and/or other immunosuppressive treatments, External radiotherapy (ERT), orbital decompression surgeries (wall number) were recorded. Hertel exophthalmometer was used for exophthalmos measurements; the angle and Hertel scores were recorded. The interpalpebral fissures were measured. The lower (scleral show) and upper eyelid retraction amounts were calculated in millimeters by measuring the distance between the limbus and the lid edge while each eye was on central fixation. All surgical treatments were performed by a single experienced surgeon (KTÖ) in the inactive period (VISA score <3) after at least six months of stability. Patients who operated on for horizontal deviation in the same session were also included in the study. Surgeries were applied to patients with diplopia, whose deviation amount was more than 10 prism diopters (PD) and could not compensate with prisms. Expanded muscle is determined with MRI, and surgery is planned with eye movements and a squint examination, and a forcedduction test. As a priority, when the deviation under 20 PD, recession was planned to only the inferior rectus muscle (IR) by the maximum of 6 mm. However, superior rectus muscle (SR) recession of the fellow eye was added if 20 PD or greater deviations. Calculations were made assuming that the amount of recession would be 1 mm=3 PD correction in vertical deviations. All surgeries were performed under general anesthesia, the muscles were recessed with a fixed suture technique. In horizontal deviations, the medial rectus (MR) muscles' recession was performed using a similar technique by an appropriate amount.Postoperative full ophthalmological examinations were performed at the 1st week, first month, sixth month, and then annually, and the final strabismus examination findings in stable condition, and additional treatments were recorded. 6th-month findings of the eyelids and exophthalmos were used in the study. Non-parametric, Wilcoxon signed rank test and chi-square tests were performed. Results: A total of 11 patients, seven females and four males, were included in the study. The mean age was 43.9 ± 7.9 (32-56) years, and the mean follow-up time was 22.3 ± 9.7 (9- 36) months. All patients had received pulse steroid therapy, and the mean total prednisolone dose was 6.14 ± 1.96 (4.5-11) grams. Moreover, four patients had additionally received ERT. Two wall (medial + inferior) orbital decompression had been performed in one patient. No patient had preoperative signs of compressive optic neuropathy or severe exposure keratopathy. Average preoperative VISA scores were 1.1 ± 0.7 (0-2). Following transactions were performed to correct vertical deviations: IR recession in only one eye (range: 4.5-6 mm) in 7 patients. In 3 patients, an IR recession (range: 4.5-5.5 mm) in one eye and an SR recession in fellow eye (range: 4-7 mm). In one patient, due to asymmetric IR involvement and severe upward gaze restriction, a bilateral but asymmetric IR recession (6 and 3 mm). In 5 cases, due to accompanying esotropia, MR recession was performed simultaneously (4 bilateral, one unilateral, range: 4-5.5 mm). The average amount of vertical muscle recession was 7.23 ± 2.7 mm. With each 1 mm recession, 3.1 PD vertical deviation was improved (calculated by taking the recession difference in the case with bilateral IR recession). All patients, preoperative strabismic findings, surgeries performed, and results are summarized in Table 1. A minimal but insignificant increase was observed in the interpalpebral fissure in the eyes undergoing surgery (p =0.180). However, the exophthalmos-Hertel scores increased significantly in all eyes performed surgery (p =0.001). Scleral show was found to be increased in all eyes performed surgery (p =0.004), besides this increase was more in eyes performed IR recession (p =0.002). The average values in the preoperative and postoperative examination findings and their comparison are summarized in Table 2. Postoperative diplopia was corrected in 9 patients statistically significantly (82%, p=0.035) in the primary position and downward gaze and tolerated with small prismatic glasses in 2 patients. As a result, one patient under-correction (4 PD) and one patient overcorrection (6 PD) in vertical squint, and one patient under-correction (6 PD) in horizontal squint were observed. However, an acceptable cosmetic improvement was achieved in all patients. One male patient, who continued to smoke and had previously taken ERT, developed TO recurrence after the 1st year. The patient, who had wide-angle esotropia, increased exophthalmos and eyelid retraction, was controlled with medical treatment, followed by bilateral MR recession, followed by blepharoplasty with fat decompression, and blepharotomy on the upper eyelids. Last, lower eyelid retraction on the side with excess scleral show was treated with helical cartilage graft. Additional surgical interventions and sequelae treatments are summarized in Table 3. Conclusion: In thyroid orbitopathy, if vertical strabismus and diplopia cannot be eliminated with conservative methods, performing a recession to vertical rectus muscles with a fixed suture technique is quite effective and safe and has predictable results in a long period. However, after surgery, an increase in exophthalmos and scleral show may become noticeable, even if minimal. It would be better to warn patients about this regard.