Prof Dagi also discussed surgical treatment of Duane syndrome and sixth-nerve palsies. She combines a medial rectus recession with a superior rectus lateral transposition, using adjustable augmentation sutures to reduce excyclotorsion induced by transposition. Her procedure included placing sutures with a scleral bite at 6mm, 8mm and 10mm from the lateral rectus insertion, which can then be selectively removed postoperatively if the desired effect on torsion is too great. She cautioned against recessing the medial rectus too far as this limits convergence, which patients find very disabling.
With regard to vertical strabismus in thyroid orbitopathy, Prof Dagi clarified when to recess one inferior rectus and when to recess both. She also gave us tips on how to avoid late overcorrection. She stressed the importance of leaving the patient with good binocular single vision in primary position and in downgaze. Ideally, their post-operative head position should be of a slight chin-up attitude so that they can descend stairs safely. Finally, she spoke about the new “miracle drug” teprotumumab (Tepezza) for thyroid orbitopathy. It reduces the size of the extraocular muscles and proptosis, and reduces strabismus in 67% of patients. Unfortunately, upon stopping treatment, the disease flares up again in 40% of patients. Many patients also withdraw from treatment due to adverse effects such as hearing loss, muscle spasms, nausea and diarrhoea. It is also highly teratogenic. Teprotumumab was US Food and Drug Administration approved in 2020 but is not yet available in New Zealand.
ANZSS’ other guest speaker was Professor Gillian Roper-Hall from the St Louis University School of Medicine in Missouri. Prof Roper-Hall eloquently educated us on the history of extraocular muscle transposition surgery, which dates back to the 1880s. She then discussed diplopia management in adults with neurodegenerative or musculoskeletal disorders. Due to their inability to maintain a neutral and upright head position, a surgical aim of achieving single vision in the normal primary position may not be appropriate or useful to these patients. Therefore, the aim of strabismus surgery here is to get the eyes straight in the patient’s best gaze position. Other measures, such as the ‘lazy readers’ available online, can be of great help to someone who can’t look down or who has nystagmus in downgaze. Using prisms, these glasses shift an image upward, obviating the need to tip the head downward. Choosing the best glasses for a patient is also vital, with single vision being best, she said. But if progressive lenses are required, it is preferable to use them for intermediate and near vision rather than for distance.
Eyes front!
Prof Roper-Hall also spoke about the ‘unique oblique’, demonstrating the phylogenetic origins of the superior oblique muscle. Starting with fish with eyes on either side of the head, she related these origins to the muscle’s current functions in forward-facing eyes. The superior oblique muscle is implicated in numerous abnormal eye movements, including congenital and acquired Brown’s syndrome, superior oblique click, myasthenia gravis, superior oblique myokymia and the rare disorder, ocular neuromyotonia. Finally, Prof Roper-Hall discussedirregular forms of diplopia, including paradoxical diplopia, visual confusion, binocular blurring, diplopia with visual-field defects, foveal displacement syndrome, intractable diplopia and the very rare monocular diplopia.
