Purpose
Retrobulbar injections are most commonly used to provide local anesthesia during intraocular surgery. Orbital injections of steroids, antibiotics, and antifungals have also been used to treat local disease processes. Given the widespread use of orbital injections for various indications, it is important to understand the anatomy of fluid diffusion within the orbit after orbital injection. This topic has been studied using latex injection in cadavers and with gadolinium injection followed by magnetic resonance imaging.1,2 The aim of our current study is to simulate true clinical circumstances by documenting the spread of retrobulbar lidocaine in cadavers and live patients undergoing enucleation.
Methods
We performed retrobulbar injections in 5 cadaver heads and 5 patients undergoing enucleation surgery. The anesthetic mixture was a 9:1 solution of 1% lidocaine with epinephrine and trypan blue dye 0.6 mg/ml. Each patient received 4 ml of this mixture injected in standard retrobulbar fashion, followed by enucleation. Each orbit was explored to determine the extent of dye spread. Intraoperative photographs were obtained. Surgery was then completed in routine fashion in live patients.
Results
In all cadavers and live patients, blue dye dispersed diffusely throughout the posterior orbit (Figures 1 and 2). Although the extent of spread varied slightly between patients, dye was apparent within the intraconal space in all patients. In our first live patient, injection caused a blue hue to the eyelid subcutaneous tissues which resolved without permanent sequelae.
Conclusions
Retrobulbar injection of medications results in diffuse spread of the medication throughout the orbit and subcutaneous tissues. This has implications for expanding the role of orbital injection of medications for local control of disease. Intraorbital therapies may be a direct route of treatment delivery for diseases refractory to standard oral or intravenous drug delivery. REFERENCES 1. Ripart J, et al. Peribulbar versus retrobulbar anesthesia for ophthalmic surgery: an anatomical comparison of extraconal and intraconal injections. Anesthesiology, 2001. 94(1):56-62. 2. Almeida D, et al. High-resolution Surface Coil Magnetic Resonance Imaging After Peribulbar And Retrobulbar Injections. Abstract presented at ARVO May 7, 2012.
Keywords: 631 orbit •
561 injection