Radial optic neurotomy using nasal and temporal approach incisions: Histopathologic study in human cadaver eyes

Objective: To examine the structural effect of radial optic neurotomy (RON) using nasal and temporal approach incisions on the nasal side of the optic nerve (ON) using dominant and nondominant hands in human cadaver eyes. Methods: Transvitreal RON was performed in 9 eyes with a microvitreoretinal blade by a right-handed surgeon. A nasal approach was used in 4 left eyes (using the right hand) and in 2 right eyes (using the left hand), and a temporal approach was used in 3 right eyes (using the right hand). Histologic sections were examined for depth of nerve penetration and for effect on critical structures. Results: The scleral canal wasfully incised in all cases. The mean depth of nerve penetration was 555 μm (725 μm using the nasal approach and 246.7 μm using the temporal approach) (P=.12). The globe was not ruptured in any eye. In a single right eye approached temporally using the right hand, the adventitial sheath of the central retinal artery was lacerated. Conclusions: RON in human cadaver eyes results in lysis of the scleral canal at the ON head. Greater depth and improved safety of incision can be achieved by always approaching the incision from the nasal side of the ON using the dominant or nondominant hand.