Written by: Alex Ireland, MD (NUEM PGY-3) Edited by: Gabrielle Ahlzadeh, MD (NUEM PGY-4) Expert commentary by: Gary Lissner, MD
The author has written an excellent illustrated review of the technique of lateral canthotomy and cantholysis for traumatic orbital compartment syndrome due to a significant retrobulbar hemorrhage. As with any procedure it is crucial to understand the indications and contraindications of the procedure. In these cases, the indication is the saving or restoring of vision lost due to excessive intraorbital pressure, and the contraindication is generally an opened globe. This is a difficult situation because there is usually limited information and there is a limited amount of time to relieve the orbital compartment syndrome. The timing of the onset of the retrobulbar hemorrhage that created the critical pressure to cause loss of vision is often unknown. The decision to decompress is usually based solely on a clinical examination without having time to obtain orbital radiologic studies and before an ophthalmologist can arrive to evaluate the patient. However, the clinical exam could be limited if the patient is not cooperative or is not conscious.
Initially a determination has to be made if the globe is lacerated or ruptured which could preclude the performance of the canthotomy and cantholysis . Either a ruptured globe or an orbital compartment syndrome can cause loss of vision. A ruptured globe can occur along with a retrobulbar hemorrhage. If the eyeball is opened, no additional external pressure should be placed on the lids or globe in order to prevent additional damage to the eye. An opened globe could be determined by seeing a laceration of the globe, seeing protruding intraocular contents, finding a very soft eye, and/or finding a distorted eye. If the eyeball is opened, a sturdy shield should be placed resting on the surrounding orbital bone to protect the eye from external pressure, and the aide of an ophthalmologist should be sought.
If it is determined that the globe is intact, a decision has to be made on clinical examination findings if a significant retrobulbar hemorrhage exists that would create enough pressure in the orbit to cause loss of vision. There is usually not enough time to wait for imaging studies to be done. The trauma could create a large enough orbital fracture that could decompress the orbital pressure and the orbital compartment syndrome. On the other hand, an orbital fracture can create orbital emphysema. Blowing of the nose by the patient can increase the emphysema and further increase the intraorbital pressure, creating a sight-threatening orbital compartment syndrome.
Acute vision loss is the key clue to a significant orbital compartment syndrome, but many trauma patients may not be able to cooperate for visual testing. The reaction of the pupil to light can be used as a sign of visual loss even in the uncooperative patient. With an orbital compartment syndrome, the pupil of the involved eye will not react well to a bright light and will have an afferent defect. However, if the patient was given narcotics the pupils can become miotic and pupil testing becomes difficult. Visual loss is not diagnostic of an orbital compartment syndrome because the trauma can create other damage that can cause visual loss including intraocular bleeding, retinal disorders, traumatic optic neuropathy, or a lacerated or ruptured globe. Trauma can cause edema and ecchymosis of the lids, but tense proptosis with very firm retropulsion of the involved eye is a key diagnostic finding of a significant retrobulbar hemorrhage. As the orbital bleeding continues, the eye is pushed forward against the tight eye lids and the intraocular pressure increases. A significant intraocular pressure increase can be used as another sign of an orbital compartmental syndrome. Checking the intraocular pressure can be difficult in the presence of massive eyelid swelling. Pulling the lids opened especially if the patient is squeezing can transmit the external pulling pressure to the eye, creating a false reading of a raised intraocular pressure. Using curved instruments, or the blunt end of bent paper clips as shown by the Blog’s author, can help open the lids. Using a topical anesthetic to reduce eye discomfort, or using injectable local anesthetic to relax the orbicularis muscle action can also help to more easily open the eyelids to obtain a more accurate intraocular pressure. Orbital compartment syndrome will limit extraocular motility on the involved side, but the unconscious patient’s motility cannot be easily tested. A significant increase of the orbital pressure and the intraocular pressure can cause pulsation of the retina arteries and full retina veins which can help with the diagnosis of an orbital compartment syndrome if the fundus is viewed.
The Blog gives a precise pictorial and written description of the lateral canthotomy and cantholyisis technique. However, unlike the author’s demonstration photos, most cases with significant traumatic orbital compartment syndrome have massive lid ecchymosis and subconjunctival hemorrhage and a proptotic eye that is pushed forward tightly against the lids. Therefore, there is frequently little room to insert the instruments at the lateral canthal angle. Extreme care must be taken to avoid unwanted damage. The author’s “tip” to insert a Morgan lens (a sclera shell if available can also be used) onto the patient’s eye is a good idea to help protect the eye, but the tight space in some cases can prevent the insertion of the lens. It is important that when working in the tight space to always work with the instruments pointing away from the eye and orbit to prevent injury to the globe, lateral rectus, lacrimal gland, or deeper orbital tissues. Always aim anteriorly toward the anterior orbital boney rim during the canthotomy. As the author suggests, the lids should be pulled or lifted away from the eyeball. Pulling the eyelid nasally and anteriorly helps tighten the crus of the lateral canthal tendon, thus making it easier to feel or strum the crus and cut it during the cantholysis. Always keep the tip of the scissors pointed away from the globe.
An orbital compartment syndrome can also occur with retrobulbar hemorrhage after surgery in the region. In such cases it can be advisable to first open the surgical wounds to determine if release of blood and clots from the depths of the wounds relieves the problem and thus eliminating the need for the canthotomy and cantholysis. In cases of retrobulbar hemorrhage after sinus or nasal surgery, the removal of nasal or sinus packing could release the blood and relieve the orbital compartment syndrome.
The Blog’s author presents a good list of potential complications from the canthotomy and cantholysis procedure. Many of the patients with significant retrobulbar hemorrhage are elderly patients who fall on their face. This group of patients can be on anticoagulants that could have potentiated the initial orbital hemorrhage and could create a problem of continued bleeding. The patients have to be observed after the canthotomy and cantholysis for continued or recurrent orbital bleeding and also for the possibility of a newly created surgical site eyelid bleeding that may not stop spontaneously. Additional surgery could be needed to stop the bleeding. Also to be considered as a complication is the fact that the release of the lateral canthal tendon lid support could cause lower lid ectropion, lid retraction, or lateral canthal deformity. Such deformities sometimes have to be surgically repaired.
In conclusion, the author has written a Blog which gives an excellent guide to perform a canthotomy and cantholysis. It can be difficult to make the decision if the procedure is needed to be done to prevent permanent loss of vision of an eye. The decision has to be based on clinical examination findings and the procedure if needed should not be delayed. After the procedure the patient needs to be observed and to have an evaluation by an ophthalmologist.
Gary S. Lissner, MD
Associate Professor, Chief Ophthalmic Plastics Service, Department of Ophthalmology, Northwestern University Feinberg School of Medicine
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Lima V, Burt B, Leibovitch I, Prabhakaran V, Goldberg RA, Selva D. Orbital compartment syndrome: the ophthalmic surgical emergency. Surv Ophthalmol. 2009 Jul-Aug; 54(4): 441-9.
Kent TL, Morris CL, Scott IU, Fekrat S. Evaluation and management of orbital hemorrhage. Eye Net magazine. 2018 July.
Jaksha AF, Justin GA, Davies BW, Ryan DS, Weichel ED, Colyer MH. Lateral canthotomy and cantholysis in operations Iraqi Freedom and Enduring Freedom: 2001-2011. Ophthalmic Plast Reconstr Surg. 2018 Jul 3. [Epub ahead of print].
How To Cite This Post
[Peer-Reviewed, Web Publication] Ireland A, Ahlzadeh G. (2019, April 15). Canthotomy [NUEM Blog. Expert Commentary by Lissner G]. Retrieved from http://www.nuemblog.com/blog/canthotomy
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