Summer - United States Special Operations Command

the only sign of OCS may be elevated intraocular pressure(IOP). 26 Without proper perfusion, sensitive structuressuch as the optic nerve and retina have a limitedtime for survival and recovery. Review of the literaturesuggests that the window for visual recovery from theonset of decreased visual acuity to decompression is perhapslimited to approximately 120 minutes. 10,27 Two casereports document a four hour delay with improvement invision to baseline, but these appear to be rare exceptions.28 Hayreh’s studies on Rhesus monkeys demonstratedcentral retinal artery occlusion of 105 minutes orlonger produced irreversible optic nerve damage, andtotal optic nerve atrophy occurred with occlusion timesthat were greater than 240 minutes. 16,29 It is therefore ofthe utmost importance to recognize and treat retrobulbarhemorrhage with prompt decompression early in this 120minute window if the devastating effects on vision are tobe reversed.Referral for immediate specialist assessment, ifavailable, should not be delayed even in doubtful cases. 24Similarly, primary examiners should not waste preciousminutes with unnecessary investigations that delay treatmentin the event specialist care is not present. 24,28,30 Ideallyan ophthalmologist would be expected to performthis emergency orbital decompression. However, if anemergency ophthalmology consult is unavailable, anyemergency responder trained to do the procedure shouldact immediately. 26 According to U.S. Navy family physicianDr. Mark Benton, “Knowledge of this procedure isa must for physicians, especially those in remote areaswhere access to ophthalmology is not readily available.The emergent lateral canthotomy can be a potentiallysight-saving procedure.” 31 In the setting of the militaryfield environment, this time window can easily lapseprior to presentation to a trained ophthalmologist. SpecialForces units are at particular risk due to separationfrom upper levels of care. In these settings, promptrecognition and treatment by 18D medical sergeants maybe required for vision saving care to be provided.DIAGNOSISIn order to undertake proper treatment, it is imperativeto recognize the signs and symptoms of acuteretrobulbar hemorrhage in the setting of trauma. OCSshould always be considered whenever there is impairmentof vision following blunt facial trauma. 32 As thepressure increases, patients may experience double vision,nausea, and vomiting. Signs of retrobulbar hemorrhageinclude a progressively tense and painful proptosis,decreasing ocular motility, asymmetric visual acuity,field restriction on confrontation testing, and decreasedpupil responsiveness – including failure to constrict todirect light stimulation or even loss of the consensual responsein comparison with the other eye. The eyelidscan become tense and edematous, and periorbital or subconjunctivalhemorrhage/ecchymosis are frequentlypresent (Figure 1). 24,33 These signs and symptoms areprogressive over minutes and changes should raise suspicionof retrobulbar pathology. 16,34,35Figure 1: OCS secondary to acute retrobulbarhemorrhage of the left eye sustained fromorbital trauma.In the setting of blunt or penetrating trauma,retrobulbar hemorrhage and OCS may be accompaniedby open globe injuries. When evaluating these patients,it is imperative that first responders maintain a high suspicionfor globe perforation first. Care should be exercisedduring examination of the ocular and periorbitalstructures to avoid undue pressure on the affected eye.Manipulation of the lids should be minimal to limit therisk of extrusion of intraocular contents in the eventglobe trauma is present. If suspicion remains based onclinical history, or signs of obvious foreign body, irregularglobe shape, peaked pupil, visible corneal or conjunctivallacerations, flat anterior chamber, or hyphema,the eye should be protected with a shield and interventionshould be left for upper echelons of care. Nevertheless,even in ideal settings, retrobulbar hemorrhage isa clinical diagnosis. Treatment cannot wait for imagingto confirm the presence of hemorrhage within the orbitor for on-call ophthalmologic personnel to arrive. Delaysfor such studies are at the expense of continued ocularischemia. Definitive care must be undertakenimmediately, once the diagnosis of orbital compartmentsyndrome from retrobulbar hemorrhage is made and thepotential of rupture or penetrating injury has been carefullyascertained and ruled out sufficiently to proceed.MEDICAL/SURGICAL INTERVENTIONMild cases of retrobulbar hematoma have beenmanaged with simple observation and medical treatment.36-38 Acute OCS requires surgical intervention toprevent vision loss. 39 However, there is often reluctanceto interfere surgically in cases of orbital hemorrhage.According to Markovits, when imperative, variousmethods including aspiration, continuous suction, andopen orbitotomy by brow and lateral approach can beEmergency Lateral Canthotomy and Cantholysis: A Simple Procedure to Preserve Vision fromSight Threatening Orbital Hemorrhage27