Neuronal complications of intravitreal silicone oil: an updated review.

Silicone oil (SiO) has a well-established role as a long-term endotamponade agent in the management of complicated retinal detachments. Complications of intraocular SiO include keratopathy, glaucoma, cataract and subretinal migration of the oil droplets. SiO tamponade can also lead to a severe optic neuropathy caused by retrolaminar migration. Nevertheless, intracranial migration of the SiO through the optic nerve posterior to the lamina cribrosa to the optic chiasm and brain is uncommon. The mechanism is still under debate, but it has been suggested elevated intraocular pressure, macrophages or optic nerve head anatomical predispositions as potential explanations. Moreover, central scotoma may develop in eyes with SiO not only at the time of oil removal, but also during the period of tamponade. We performed a PubMed search of neuronal complications of silicone oil over a period of 25 years. This review summarizes our current understanding of the specific pathogenic mechanisms of intraocular SiO neuronal side effects, concluding that pre-existing glaucoma and optic nerve abnormalities are the main risk factors associated with this damage. In their absence, the risk of extraocular SiO penetration is so low that the use of SiO endotamponade in complex retinal detachment patients does not need to be modified. MRI images to assess extraocular SiO migration are only necessary in very few and special cases, such as patients with optic nerve abnormalities and glaucoma.