Abstract
Purpose: :
Introduction: Infiltrative thyroid associated myopathy is due to the presence of glyco–aminoglycans and hyaluronan in the extra–ocular muscles. Fibrosis and contracture of the extra ocular muscles may result in restrictive ocular motility, affecting one or more muscles in one or both eyes, resulting in misalignment and diplopia. Vertical muscle imbalance in dysthyroid orbitopathy is frequently due to significant restriction of the inferior rectus. Limited upgaze with varying degrees of hypotropia in the position of primary gaze accounts for the commonest indication for surgery. The inferior rectus is restricted commonly due to infiltrative myopathy.
To demonstrate a more predictable outcome in vertical thyroid–related ocular deviation with the use of adjustable hang – back sutures.
Methods: :
The medical records of 16 patients with dysthyroid ocular myopathy who underwent surgery for vertical ocular misalignment were reviewed retrospectively. Data relating to duration of disease, systemic treatment, ocular symptoms and signs were noted. The pre–operative ocular deviation, the surgical dose, the post–surgical deviation besides the amount of suture adjustment and post–operative deviation were analysed.
Results: :
Orbital decompression had been performed in 10 patients. Muscle recession surgery using the hang back technique in each vertical muscle was 3.25 mm on average with a range between 0–9mm. Vertical ocular motility increased from an average of –2.2 pre–operatively to –0.62 post operatively. Twelve patients (75%) obtained good surgical outcomes, which included cessation of diplopia in primary gaze, stable ocular alignment, fuller ocular ductions and a high degree of stereopsis. Five patients required the use of prisms. However, the use of adjustable sutures provided a greater range of correction in the immediate post–operative period as 75% of the patients benefited from an adjustment.
Conclusions: :
Strabismus surgery was undertaken in patients with dysthyroid eye disease only when stability of ocular deviation was noted. Adjustable sutures enabled greater correction of misalignment in the immediate post–operative period, relieving diplopia in the functional positions of gaze. Appropriate correction of deviation in the absence of adjustable sutures would have rendered patients under corrected or overcorrected.
Keywords: extraocular muscles: structure • strabismus: treatment • strabismus