Postoperative drift in patients with thyroid ophthalmopathy undergoing unilateral inferior rectus muscle recession

Extraocular muscles of patients with thyroid ophthalmopathy (TO) may respond differently to strabismus surgery than those of other strabismic patients. This study reports postoperative alignment changes in patients with TO compared with patients with non-restrictive strabismus following unilateral inferior rectus muscle recession (IRR).

We reviewed records of patients with and without TO who underwent unilateral IRR. Group A had adjustable muscle sutures, while Group B had permanent or semi-adjustable sutures. Controls were patients undergoing adjustable unilateral IRR for other indications.

Mean preoperative hypotropias were 17 ± 9, 21 ± 7, and 11 ± 4 PD for groups A (n=13), B (n=14), and controls (n=19), respectively. Postoperative day one (POD1) measurements after adjustment were 1.2 ± 2.5, 3.7 ± 4.9, and 0.3 ± 2.4 PD, respectively, representing overall undercorrections in all cases (the preoperative deviation was given a positive (+) value and overcorrections were deemed negative (-) deviations). Dose response from linear regression analysis of thyroid patients compared with control patients for IRR was 3.26 PD/mm (SE 0.18) vs 2.38 PD/mm (SE 0.18) (p=0.001). Mean final measurements were -0.7 ± 5.6 (overcorrection), 2.7 ± 5.7, and 1.7 ± 5.7 PD of hypotropia, respectively. Final overcorrections occurred in 23%, 14%, and 16% of patients, for adjustables, permanent sutures, and control subjects, respectively. Drifts from POD1 measurements after adjustment to final measurements were -1.9 ± 4.3, -1.0 ± 4.6, and 1.4 ± 5.9 PD respectively (p=0.05 for comparison between Group A and controls).

TO patients with adjustable sutures drift toward postoperative overcorrection.