Next up in our discussion on facial nerve blocks–following previous posts on how to anesthetize the mid-face with the infraorbital nerve block and how to anesthetize the lower face with the mental nerve block–is this discussion on the ophthalmic nerve block.
I believe this is the hardest to master among the facial nerve blocks. It is also slightly more intimidating, as it involves needle entry through the skin, rather than within the mouth.
This said, this block is as safe as (if not safer than) the other techniques. With proper needle entry, the globe is not at risk (as it can be with the infraorbital block) and with proper skin preparation it is more aseptic than any of the intra-oral techniques.
How it’s done:
- The ophthalmic block is accomplished by percutaneous local injection at the point where the lateral and medial branches of the supra-orbital, supra-trochlear, and infra-trochlear nerves exit from the superior aspect of the orbit.
- This point is the supra-orbital notch, which is a fairly subtle landmark. You can imagine its location by having the patient stare straight ahead. It lies in line with the pupil with neutral gaze, palpable along the supra-orbital rim.
- Ask the patient to lie supine, or at least semi-recumbent with the head at rest. After cleansing with an aseptic solution, place a skin wheal over the anatomic site of entry.
- Finally, inject towards the supraorbital notch. The patient should experience transient parasthesias over the forehead. This predicts a successful block.
- Approximately 1-3 mls of anesthetic are injected around the area of the supra-orbital notch.
Pro-tip: press a roll of dental gauze (or even your gloved finger) firmly under the orbital rim as you inject. This prevents the anesthetic from ballooning out into the upper eyelid.
A Simpler Alternative
When you are first learning this technique, it may be worthwhile to practice this simpler alternative. While slightly less elegant, this method is much simpler.
- Rather than aiming for the landmark of the supra-orbital notch, simply place a line of anesthetic along the superior orbital rim.
- The needle is inserted at the lateral margin of the eyebrow, directed towards the medial aspect while aspirating, and then anesthetic is injected as the needle is withdrawn.
- A larger volume of an aesthetic will be required than with the former technique.
- Don’t forget to hold pressure along the superior eyelid, as ballooning of the anesthetic can be an even bigger problem with this method.
A successful block will produce anesthesia of the patient’s forehead and anterior scalp. A very successful block may also include the infratrochlear nerve branch, which is typically found in the most medial aspect of the superior orbital rim. This will also produce anesthesia of the upper eyelid, which can be useful for repairing lacerations in this location.
Complications of this procedure are few. Hematoma formation or eyelid swelling can occur, but can be treated with local pressure and ice. As with any percutaneous injection, make sure to warn the patient about signs and symptoms of infection.
What has your experience with the ophthalmic nerve block been like? Feel free to share in the comments below.