Surgical treatment of strabismus in thyroid eye disease: characteristics, dose-response, and outcomes

To describe the surgical management, dose-response, and postoperative outcomes of strabismus surgery in patients with thyroid eye disease.

The medical records of patients operated on between 2014 and 2018 were reviewed retrospectively. Patient characteristics and surgical data were collected. Motor success was defined as vertical deviation of ≤5^Δ and horizontal deviation of ≤10^Δ; sensory success, as no diplopia in primary gaze.

A total of 76 patients (mean age, 62.2 ± 12.9 years; 50 females) underwent 87 surgeries, most commonly unilateral inferior rectus recession (unilateral IR, 48%) and bilateral medial rectus recession (bilateral MR, 23%). Motor success was achieved in 69% and sensory success in 58%. For unilateral IR surgery, the dose-responses were 3.25^Δ/mm (SE = 0.616; β = 0.650; P < 0.001) at distance and 2.48^Δ/mm (SE = 0.752; β = 0.472; P = 0.002) at near; for bilateral MR surgery, 3.93^Δ/mm (SE = 0.997; β = 0.680; P = 0.001) at distance and 5.05^Δ/mm (SE = 1.374; β = 0.655; P = 0.002) at near. Median (Q₁, Q₃) postoperative drift was toward overcorrection for both procedures (unilateral IR, -2^Δ [-8, 0] at distance and -2^Δ [-7, 0] at near; bilateral MR, -2^Δ [-8, 2] at distance and -2^Δ [-10, 0] at near). Sex, age, duration of strabismus, prior orbital decompression, and concurrent vertical and horizontal procedures were not associated with dose-response or postoperative drift.

Concurrent vertical and horizontal surgery did not affect the motor success rate, dose-response, or postoperative drift. Although unilateral IR surgery had a larger dose-response at distance, bilateral MR surgery had a larger dose-response at near. Most procedures tended to have a postoperative drift toward overcorrection.