LAUSR

ABSTRACT Background/Aims: We performed a retrospective analysis to examine clinical results, establish a dose-effect coefficient and analyze the long-term efficacy of tendon elongation with bovine pericardium (Tutopatch®) for surgical correction of severe esotropia, occurring after three-wall orbital decompression for dysthyroid optic neuropathy in patients with Graves’ orbitopathy (GO). Methods: Tendon elongation of the medial rectus muscle (MR) was performed in our institution using an interponate of bovine pericardium in 60 patients (27 underwent unilateral and 33 bilateral surgery). Success-rate (total horizontal deviation of 10 prism-diopters (PD) or less and evidence of binocular single vision with or without prism glasses) and horizontal motility were examined 3 months, 1 and >4 years after surgery. A dose-effect coefficient for deviation reduction (PD) per recession distance (mm) was established. Results: Horizontal deviations between 28–80Δ were corrected. Diplopia in primary-gaze disappeared in 65% of the patients after 3 months and in 83% after one year (including 12 patients who underwent subsequent surgery after 3-month follow-up). Patients with deviations ≤40Δ after unilateral and ≤50Δ after bilateral tendon elongation showed higher primary success-rates after 3 months (78% and 72%). Vertical deviations (≤10Δ) were corrected by the procedure in 28% without need of recession of the inferior rectus (IR). Only 3 patients showed overcorrection after one year. One of these underwent revision surgery, in which the interponate was no longer discernible from surrounding fibrotic scar tissue. At >4-year follow-up (4.3–15years) effects were stable and 95% of patients showed fusion in primary gaze. Median dose-effect coefficient was lower after tendon elongation (1.8Δ/mm) compared to conventional medial rectus recession in patients with GO. Horizontal motility was slightly decreased, but much more symmetric around primary gaze. Conclusion: Tendon elongation with a bovine pericardium implant is a safe surgical method, suitable to correct severe esotropia after decompression surgery. A lower dose-effect has to be taken into account. Patients with esotropia ≥42Δ should not be treated with unilateral, but bilateral tendon elongation, to avoid undercorrections. In patients with deviations ≥52Δ it has to be further investigated if the application of even higher elongation distances is viable or if another approach—the recession of more than one rectus muscle has to be performed simultaneously to handle the severe restriction. Generally, a step-by-step approach is advisable, since small vertical deviations could also be corrected in a third of patients with the procedure and the dose-effect was more variable as in medial recessions without tendon elongation.