Surgical decompression of the intraorbital meningeal sheath of the optic nerve has undergone a recent resurgence of interest. Previously, the procedure had been reserved only for the most desperate cases of severe visual loss associated with chronic papilloedema. However, recent investigations have demonstrated the operation's efficacy not only for chronic papilloedema and pseudotumor cerebri, but also for the optic neuropathy associated with the acute retinal necrosis syndrome, traumatic subdural haematomas of the optic nerve and progressive nonarteritic ischaemic optic neuropathy. In this article, we review the previous literature concerning optic nerve sheath decompression, the indication for the procedure, its techniques and results. Finally, we propose that optic nerve sheath decompression may be effective for what appear to be very different optic neuropathies because the operation may reverse optic nerve ischaemia, a common pathophysiologic feature of all these disorders.