Timing of operation and therapeutic effect of endoscopic optic nerve decompression for traumatic optic neuropathy

Abstract

To observe the optimal timing of operation and the therapeutic effect of endoscopic optic nerve decompression for traumatic optic neuropathy (TON). The clinical records of 90 consecutive patients with TON (93 eyes) after head and/or maxillofacial trauma from April 1998 to March 2007 were reviewed and analyzed. All patients were either unresponsive or intolerant to medication before they underwent intranasal endoscopic optic nerve decompression. The time interval between the injury and operation ranged from one day to 97 days (median 5.5 days). Among the 93 eyes, there were 71 eyes with no visual acuity before operation and 22 eyes with residue visual acuity, including light perception in 1 eye, hand movement in 5 eyes, counting fingers in 13 eyes, 0.04 in 1 eye, and 0.1 in 2 eyes. Duration of follow-up ranged from 6 days to two years (median 8 days). After decompression, 35 patients (36/93 eyes, 38.7%) showed improvement of visual acuity, 53 patients (55 eyes, 59.1%) remained the same as before operation, while 2 patients (2 eyes, 2.2%) showed decreased visual acuity. Among patients with visual acuity beyond light perception before decompression, 68.2% of them (15/22 eyes) experienced visual improvement, whereas only 22.9% (8/35 eyes, 0.02 in two eyes) among patients who lost visual acuity immediately after injury, and 36.1% (13/36 eyes, 0.02 in five eyes) among those who lost visual acuity gradually after injury. There was a significant difference in visual improvement between group with visual acuity and group with no visual acuity (chi(2) = 11.864, P < 0.01). Among patients with no visual acuity, 41.2% of those (7/17 eyes) who underwent operation within 3 days of injury, experienced improvement in visual acuity, compared with 25.9% (14/54 eyes) for those who underwent the operation more than 3 days after injury. It was indicated that no significant difference in visual improvement between these two groups (chi(2) = 1.46, P > 0.05). When comparing different sites of fracture, the effect of surgery was the most desirable (55.6%, 10/18 eyes improved) if the fracture occurred simultaneously in both exterior and interior walls of optic canal, followed by the interior wall fracture (45.7%, 21/46 eyes). The operation was less effective if there was no fraction (20%, 4/20 eyes) or if the fracture occurred in exterior wall alone (11.1%, 1/9 eyes). Endoscopic optic nerve decompression is a minimally invasive procedure with no adverse cosmetic effects. Early operation is recommended for saving vision, even though visual acuity is lost immediately after injury. However, the satisfactory clinical effects of endoscopic optic nerve decompression require further study.