Sir,

We congratulate Drs Verity and Rose on their excellent update and review of the management of acute thyroid eye disease.1 They state that use of Botulinum toxin (BoNTA) for eyelid retraction in this disease state is inadvisable. Certainly, through a transcutaneous approach we agree that the correct placement of BoNTA without affecting the superior rectus or orbicularis oculi is variable in both its efficacy and effectiveness.2 However in our experience, we find transconjunctival administration to be a much safer and predictable approach.

Injection of BoNTA through a transconjunctival approach is ideally suited for patients with active thyroid orbitopathy and moderate or severe eyelid retraction. It can be used as an adjunct to other supportive therapies.3 Rather than using the standard 2.5 units of BoNTA that would achieve complete ptosis in patients without thyroid orbitopathy, we have found 5 units in 0.1 ml to be safe and effective in patients with thyroid eyelid retraction. This very rarely gives rise to severe or prolonged ptosis, and we have not encountered BoNTA-induced hypotropia or superior rectus underaction; a finding consistent with studies that have utilised even larger subconjunctival doses.4, 5

Topical local anaesthetic is instilled and the upper eyelid is everted. A minimum dose of 2.5 units and maximum of 7.5 units (usual dose 5 units for scleral show 1–2 mm) BoNTA (Botox diluted 5 units/0.1 ml, Allergan Limited, UK) is administered via a single injection into the subconjunctival space at the superior margin of the central tarsal plate. Within 48 h, eyelid retraction and lagophthalmos improves and a better aesthetic appearance is achieved, particularly during active disease when patients may be unsuitable for surgical lowering.