Traumatic Optic Neuropathy Treatment Trial (TONTT)

The pathophysiology of Traumatic Optic Neuropathy (TON) is thought to be multifactorial, and some researchers have also postulated a primary and secondary mechanism of injury.TON is categorized as direct or indirect.In indirect TON cases, the injury to the axons is thought to be induced by shearing forces that are transmitted to the fibers or to the vascular supply of the nerve. Studies have shown that forces applied to the frontal bone and malar eminences are transferred and concentrated in the area near the optic canal. The tight adherence of the optic nerve's dural sheath to the periosteum within the optic canal is also thought to contribute to this segment of the nerve being extremely susceptible to the deformative stresses of the skull bones. Such injury leads to ischemic injury to the axons of the retinal ganglion cells within the optic canal. At present, no studies validate a particular approach to the management of TON. There are three management lines for these patients that include 1)observation only;2)medical treatment with high or megadoses of methylprednisolone; and 3)surgical intervention. Generally no line precedes the others and additionally, medical or surgical interventions may result in serious side effects or complications. In 2005, the results of the Corticosteroid Randomization after Significant Head Injury (CRASH) trial raised concerns regarding the use of mega dose steroids in traumatic brain injury. This study was the largest randomized study that evaluated steroids in patients with traumatic brain injury and was stopped early due to the significantly increased risk of death in patients that received mega dose steroids at their 6-month follow-up when compared with the placebo group (25.7% vs 22.3%; Relative Risk 1.15 Confidence Interval 1.07 to 1.24; p=0.0001). Although the etiology of the increased risk of death was not determined, the findings of this study should be taken into consideration when managing cases of TON with concurrent traum