Strabismus management

Radiology and other advanced imaging techniques such as magnetic resonance imaging (MRI) have greatly increased understanding of the pathophysiology of many strabismus conditions and transformed the strategies for treating them, according to Lionel Kowal MD. “It is thanks to advances in imaging techniques that we have been able to introduce new treatment paradigms. We need to remember, however, that there are abnormal radiological findings that seem to have no clinical significance and radiological assessment in alphabet patterns can be confusing,” he told delegates attending the European Society of Ophthalmology (SOE) Congress in Barcelona. Above all, Dr Kowal, a Senior Fellow at the Royal Victorian Eye and Ear Hospital, University of Melbourne, Australia, stressed the importance of imaging in avoiding incorrect or incomplete diagnoses. “We need to educate and enthuse ophthalmologists and radiologists of the importance of imaging in strabismus, as the surgical management of many of these conditions is very dependent on the correct classification,” he said. Dr Kowal noted that while radiology is useful for a range of strabismus conditions, it is most relevant in abduction deficits, strabismus in high myopia and superior oblique palsy cases. The optimal means of assessing superior oblique function and to diagnose atrophy is using an MRI scan, and it is vital to distinguish between real and apparent or pseudo-superior oblique palsy (SOP). “SOP is often used as a synonym for a condition that resembles SOP. When SOP is diagnosed by strabismus doctors, it is wrong around 50% of the time. The most accessible technique to reliably diagnose SOP is to demonstrate atrophy on coronal scans,” he said. Dr Kowal said that some ophthalmologists have questioned whether it is actually important to know the most accurate diagnosis. “This is because most of the time we are going to do inferior oblique weakening irrespective of the precise cause. However, I think precise diagnosis is important because some pseudo-SOP causes require different surgery. True SOP has other implications: some are rarely due to tumour and the natural history is probably to get worse,” he said. Imaging is also important in congenital superior oblique palsy, said Dr Kowal. “In a prospective study I showed that 20% of patients with radiologically demonstrated atrophic superior oblique palsy on MRI scans have unequivocally floppy tendons after surgery, probably requiring superior oblique tightening. If the patients did not have an atrophic SOP, none of them had a floppy tendon. Superior oblique tightening is a more difficult and higher morbidity procedure than inferior oblique surgery, so this is one good reason to know the precise diagnosis before surgery,” he said. Lionel Kowal: strabism@netspace.net.au

Tags: strabismus