Abstract
Abstract: :
Purpose:Radial optic neurotomy (RON) has been proposed as a new therapeutic option for central retinal vein occlusion (CRVO). RON is supposed to relieve pressure on the central retinal vein and thereby improve visual outcome but as yet the method remains controversial. Recently, a histopathologic study of porcine eyes after RON without CRVO has demonstrated marked gliosis, complete axonal loss, hemorrhage and interstitial edema within the optic nerve (ON) at the neurotomy site. Here we report the first human histopathologic findings after RON in CRVO. Methods: RON (together with cataract surgery) was performed in a 65–years–old male patient with a 2–week–history of visual decrease and an angiographically proven ischemic CRVO in his right eye. A CRVO–knife was used to perform a single incision on the nasal optic disc. Because of subsequent vitreous hemorrhage and neovascular glaucoma, vitrectomy, panretinal photocoagulation, cyclophotocoagulation, and silicone oil tamponade was performed 2 months later. Despite these interventions the eye became painful and blind and had to be enucleated. – The specimen was immersion–fixed in 4% paraformaldehyde. Serial horizontal paraffin sections of the pupil–ON–block were stained with either H&E or PAS. The retrobulbar ON was cut transversely and examined in a similar fashion. Results: Histology showed multiple retinal hemorrhages and pre– and subretinal membranes. At the nasal side of the ON, fragments of Bruch’s membrane surrounded by retinal tissue were displaced towards the center of the papilla. At this site, a discrete scar could be traced down to the cribriform plate, not reaching the central retinal artery and without detectable involvement of the sclera. The transverse sections of the ON demonstrated advanced atrophy with only a small area of viable nerve fibers in the temporal sector. No specific distinct scar formation or localized inflammation were found in either the retrobulbar ON itself or its sheaths. Conclusions: Given the time period between RON and enucleation as well as the multiple histopathologic findings related to CRVO itself and to surgical trauma in this specimen, interpretation of RON–specific changes is difficult. Displacement of retinal tissue, however, and a scar extending into the cribriform plate but not involving the central retinal vessels or the retrobulbar ON, can unequivocally be attributed to RON. – The mechanisms of RON in possibly improving visual outcome in CRVO remain ambiguous, and further histopathological correlation at least in an animal model appears mandatory.
Keywords: optic disc • pathology: human • microscopy: light/fluorescence/immunohistochemistry