Relation between preoperative orbital morphology and long-term ophthalmological outcome up to fifteen years of age in unicoronal synostosis.

Background: Long-term ophthalmological manifestations constitute the main functional issue in unicoronal synostosis (UCS), with a large interindividual variability. The relation between preoperative orbital morphology and long-term functional outcome is not fully understood.

Methods: In this retrospective cohort study, non-syndromic UCS patients treated with fronto-orbital advancement and remodelling (FOAR) between 2014 - 2023 at Necker Hospital, Paris, France or Uppsala University Hospital, Sweden were included and paired to controls. Preoperative computed tomography (CT) and all ophthalmological follow-up examinations ≥1 year post-operatively were included. Objective 3D measurements on CT scans were used to analyse symmetry, local and global shape differences. The degree of severity in preoperative orbital morphology was correlated to long-term outcomes of oculomotor disorders, amblyopia, anisometropia, and astigmatism.

Results: Thirty-six patients and thirty-six controls were included. The mean ages were 8.5 ± 7 (0.3 - 34) months at CT examination, 12 ± 7 (8 - 36) months at FOAR, and 6 ± 3 (2 - 15) years at last ophthalmological examination. Ipsilaterally, large global shape deformity of the orbit related to strabismus, vertical strabismus in particular, and pseudo trochlear palsy at long-term follow-up. Neither preoperative contralateral morphology nor age at FOAR were associated with ophthalmological outcomes.

Conclusions: Ipsilateral oculomotor disorders at follow-up correlate with the degree of global orbital deformity primarily caused by the synostosis, suggesting that preoperative ipsilateral morphology might constitute a predictive factor for poor ophthalmological outcome, whereas neither age at FOAR nor contralateral morphology influenced long-term ophthalmological outcome. FOAR does not seem to prevent or reduce strabismus.