Navigation-guided transcaruncular orbital optic canal decompression in indirect traumatic optic neuropathy: long-term outcomes

Abstract

Purpose: To determine the surgical outcomes using navigation-guided transcaruncular orbital optic canal decompression (NGTcOCD) and investigate the relationship between visual prognosis. visual evoked potential (VEP), association with DeLano type of optic canal and Onodi cells in patients with indirect traumatic optic neuropathy (TON).

Design: Prospective observational.

Methods: Fifty-two consecutive patients with indirect TON unresponsive to steroid therapy were divided into three groups where Group I comprised of cases with optic canal fracture who underwent NGTcOCD, Group II without optic canal fracture who underwent NGTcOCD and Group III, no-decompression group who chose not to undergo NGTcOCD. An improvement in visual acuity (VA) at 1 week, 3 months and 1 year and amplitude and latency of VEP at 1 year were considered as primary and secondary outcomes, respectively.

Results: The mean VA improved from 2.55±0.67 and 2.62±0.56 LogMAR at presentation to 2.03±0.96 and 2.33±0.72 LogMAR at final follow-up among Group I and Group II patients, respectively (p<0.001 and p=0.01). Statistically significant improvement observed among both the Groups in VEP amplitude (p=<0.01) and among Group II in VEP latency (p<0.01). Both Group I and Group II patients have better outcomes than patients in no-decompression group. VA at presentation and Type 1 DeLano optic canal were observed as significant prognostic factors.

Conclusions: NGTcOCD serves as a minimally invasive transcaruncular route to the optic canal which enables ophthalmologists to perform decompression from the anterior-most orbital end under direct visualisation. Patients with indirect TON with or without optic canal fracture and unresponsive to steroid therapy when managed with NGTcOCD have shown comparable and superior outcomes.

Keywords: Optic Nerve; Orbit; Trauma.