Wie tief muss die radiäre Optikusneurotomie zur Therapie des retinalen Zentralvenenverschlusses sein?

Biomechanical Assessment of Radial Optic Neurotomy

PURPOSE

A biomechanical model was constructed to simulate the potential therapeutic effect that the surgical procedure radial optic neurotomy (RON) would have on an eye with a central retinal vein occlusion.

DESIGN

Experimental study.

CONTROLS

Model eyes undergoing RON were compared to control eyes under the same baseline conditions.

INTERVENTION

Radial optic neurotomy. We modeled the optic nerve, lamina cribrosa, and the sclera separately and then reassembled the components. Material properties of the sclera and lamina cribrosa were extracted from the literature and both stiff and more elastic values were used for the optic nerve. Intraocular and arterial pressures were varied across a wide range in the analysis.

MAIN OUTCOME MEASURE

Change in central retinal vein lumen size.

RESULTS

Over a clinically relevant range of boundary conditions, the increase in the lumen area of the central retinal vein lumen after RON remained trivial, ranging from 1% to a maximum of 5%.

CONCLUSIONS

The biomechanical effect of RON is negligible, and is unlikely to be a procedure that could mechanically ameliorate the clinical sequelae of a central vein occlusion.

Chirurgische Therapie retinaler Venenverschlüsse

The range of therapeutic options for the treatment of retinal vein occlusions has been decisively extended by three new surgical methods: radial optic neurotomy (RON) and retinal endovascular lysis (REVL) for central retinal vein occlusion, and arteriovenous dissection (AVD/sheathotomy) for branch retinal vein occlusion. None of those methods has been tested in randomised studies meeting the requirements of evidence-based medicine. It is therefore difficult to assess the relative values of the individual procedures and determine in what precise circumstances each is indicated. The difficulties are compounded further by the use of these techniques in association with new and promising intravitreally injected drugs (e.g. steroids and angioinhibitors), which makes it even more difficult to assess the real efficacy of the surgical methods. In this paper we discuss the three different surgical methods and try to evaluate their clinical benefit.