Learn the steps of this potential vision-saving technique.
Lateral canthotomy is an extraordinarily rare, but potentially vision-saving procedure. It is used to relieve increased intraocular pressure found in orbital compartment syndrome in the emergency setting. If not done or performed incorrectly, it is associated with severe morbidity —vision loss.
Although this procedure is within an Emergency Physician’s scope of practice, very few physicians have seen or will ever perform the procedure during their careers. There are many procedures physicians learn during their training; however, the opportunity is unlikely a lateral canthotomy will be performed in vivo due to its low incidence (1). We chose to build a trainer to demonstrate to our trainees when and how to execute such a rare but important vision saving procedure.
Current synthetic and organic models are either expensive or are single use. We chose to build a canthotomy trainer described by Rodrigo Kong et al in the African Journal of Emergency Medicine. Once constructed, we assessed its use in residency training (2). This model was chosen as it could be created with all non-organic material.
The trainer we describe costs approximately $3 per model with the model allowing for the procedure to be performed on reciprocal sides; thus, allowing physicians to perform the procedure twice. Furthermore, by replacing the outer tape and elastic band, one essentially resets the model to be used again.
This trainer was used in a recent EM education session and learners had an improvement in comfort level from a mean of 1.9 prior to the trainer use, to a mean of 4.5 (using a 1 [very uncomfortable]through 5 [very comfortable]questionnaire, before and after the use of this trainer). Learners felt that the trainer was a good representation of the eye and allowed for the practice of performing a lateral canthotomy.
Items required for the eye model:
Ping pong ball 4.99/12ct
10mL Ziploc recyclable container and lid 2.79/ 8ct
Pressure foam tape
3M Transpore tape 13.50/ 12ct Foam Tape 12.50/ 1ct
#64 rubber bands 1.27/ 4oz
Scalpel or Scissors 3.99/ 1ct
Silk tape 3.15/ 1ct
Total Cost 3.50 per eye model
Assembly for eye model (as outline by Kong et. al.):
Step 1: Cut out the base of the Ziploc recyclable container using the scalpel so that the ping pong ball can be pushed from the inside of the container out where the ball is bulging but not easily pulled through.
Step 2: Place the ping pong ball on a tape roll, then over the Ziploc 10mL lid cover, and then place the base of the Ziploc container over and close. The tape roll should hold the ball up so it is slightly bulging through the hole made in Step 1.
Step 3: Using the scissors, transect the rubber band. Then using the scalpel, make a horizontal incision into the middle third of the rubber band to create a circle representing the upper and lower limbs of the lateral canthus tendon.
Step 4: Cut two three- to four-inch pieces of 3M Transpore Tape and fold them over one of the rubber bands at the area of incision that was made using the scalpel to represent the limbs of the tendon.
Step 5: Using the foam tape, cut about four- to five-inches in length, then cut longitudinally to have two pieces that are four- to five- inches in length and about 1.5 inches in width. This will be used to make the soft tissue around the eye.
Step 6: Using one of the foam tape pieces above that is now 4-5 inch in length and about 1.5 inch in width, there will be four cuts in the lateral margins, made via scissors. The first pair of cuts will be made in the middle third of the foam tape about 1.5 inches apart. The next two cuts will be made lateral to the initial about 0.5cm. Ultimately there will be three flaps. one middle large flap about 1.5 inches and two small flaps on the side about 0.5cm. Bend the small lateral flaps on to themselves.
Step 7: Repeat Step 5 with the other foam tape piece that is four- to five-inches in length and about 1.5 inch in width.
Step 8: Using one of the cut foam tape pieces from Step 5, place it over the cut rubber band from Step 3 so that the middle flap will bend over the middle third of the rubber band. Do so the same with the other foam tape piece from Step 6, on the lower portion of the middle third ⅓ of the rubber band.
Step 9: Place the rubber band and the two foam pieces over the bulging ping pong ball that is in the Ziploc container. Fold the foam tape over the ping pong ball to cover it and form the upper and lower eyelids.
Step 10: Use silk tape to go around the Ziploc container circumferentially to hold the foam tape together against the ball, against the container. Color eye for added effect.
Equipment needed for a lateral canthotomy:
Laceration Repair Kit
Scissors, Pickups, Hemostat, Syringe, 18G and 27G, Gauze
Lidocaine 1% with Epi
Performing Lateral Canthotomy:
Step 1: Using the syringe and 18G to draw lidocaine with epinephrine. Exchange the needle for 27G and inject solution into the lateral canthus pointing cauda and cephalad.
Step 2: Use the hemostat to clamp the lateral canthus and [hold for up to 30 seconds]and repeat, clamping the inferior canthus.
Step 3: Use the scissor to cut the lateral canthus in a straight line posteriorly towards the orbital rim. Then make another incision caudad to cut the inferior crus.
*Optional make another incision cephalad to cut the superior crus.
References:
- Amer E, El-Rahman Abbas A. Ocular Compartment Syndrome and Lateral Canthotomy Procedure. J Emerg Med. 2019 Mar;56(3):294-297. doi: 10.1016/j.jemermed.2018.12.019. Epub 2019 Jan 21. PMID: 30679067.
- Kong R, Kaya DP, Cioe-Pena E, Greenstein J. A low fidelity eye model for lateral canthotomy training. Afr J Emerg Med. 2018 Sep;8(3):118-122. doi: 10.1016/j.afjem.2018.02.002. Epub 2018 May 5. PMID: 30456160; PMCID: PMC6223586.
