Blunt Trauma and Open Globes
THE CLINICAL CHALLENGE
Severe blunt trauma to the eye can be a diagnostic dilemma owing to the wide variety of possible injuries. What makes this subject especially difficult is that examining the eye may be difficult or even contraindicated in certain instances, and the degree of posterior exam findings from trauma (which requires a dilated fundus exam) may not be deduced from the anterior segment appearance. When dealing with any severe trauma to the eye, perhaps the most important clinical and diagnostic question to answer is whether an open globe injury is present. In the United States, the estimated incidence of open globe injuries is 4.49 per 100 000 annually, and whereas open globes consist of 2.0% of ocular trauma cases, they are responsible for 8.3% of expenses related to ocular trauma.1 Young men appear to be at most risk for open globe injuries, through either occupational or environmental hazards or from assault.
Blunt injuries involving the eye and orbit may make ophthalmologic evaluation difficult and risky, and other injuries may simulate open globe injury. Examination itself may be difficult or even impossible without advanced support owing to presentation, such as an uncooperative pediatric patient or a patient with altered mental status from medications or illicit substances. However, suspicion and rapid triage of open globe injuries is key to maximizing visual recovery and globe loss.
The effects of blunt trauma to the eye vary depending on the amount and trajectory of force. Anterior segment injuries are from direct contusions to the eye itself or from force transmitted through the orbit or eyelid. Posterior segment injuries are typically from shockwave effects secondary to the anterior-posterior compression of the globe from blunt force trauma. The shockwave effects cause direct tissue damage and abnormal vitreous traction to the eye and subsequent injuries such as retinal dialysis, vitreous hemorrhage, and commotio retinae. In cases of severe compression, an open globe may even occur.
An open globe is defined as a full thickness wound of the sclera or cornea typically either after an injury that penetrates the eye or from an occult rupture after blunt injury. The largest proportion of volume of the internal contents of the eye is incompressible liquid (aqueous and vitreous humor). A blunt injury of significant force may cause the intraocular pressure (IOP) to rise to a point where the eyewall cannot contain the pressure and thus rupture at its weakest areas (limbus, posterior to the rectus muscles, and old wounds from intraocular surgery). Eyewall rupture results in expulsion of vital portions of the eye, including the lens, iris, retina, and choroid. Even if the globe is not ruptured, the force and the subsequently increased IOP and shockwave effects of the injury may cause other vision-decreasing pathology.
In contrast, the pathophysiology of open globe injuries from lacerating or penetrating injuries, usually from sharp objects or intraocular foreign body (IOFB) entry, is straightforward. These injuries typically enter through the anterior portions of the eye (cornea, limbus, anterior sclera) and typically do not cause damage to the surrounding orbital structures. The proper terminology to describe open globe injures is listed in Table 45.1.2
APPROACH/THE FOCUSED EXAM
History and Presentation
After any life-threatening injuries are addressed, a detailed history and exam of the eye should be obtained if possible. The timing of the injury and mechanism should be noted, especially if there is concern for an open globe injury. Although the mechanism is important, the severity or force of the mechanism is much more important in determining whether an open globe is present. Severe blunt trauma from bungee cords, assaults/fights, paintball injuries, falls, all-terrain and motor vehicular collisions, and sports injuries without protection are of particular risk in causing open globes.
The relative cleanliness of any penetrating injuries and the potential for a retained IOFB should also be investigated. Do not overlook the potential for retained foreign bodies from a wide variety of mechanisms such as hammering metal on metal, sharpening metal, or an explosion. Dirty or contaminated objects, especially if organic (like wood), may increase the risk of concurrent development of endophthalmitis with the open globe injury. In addition to the timing and mechanism of the injury, other important information includes whether the patient is experiencing pain or a decrease in vision and, if so, the timing of the pain or acuity change relative to the time of the injury.
Even with grievous injuries to the eye, a past medical and surgical history is important to obtain. Blunt injuries to the eye can sometimes precipitate or worsen existing systemic eye conditions that can cause vision loss. For example, in a diabetic patient with proliferative diabetic retinopathy, an accidental blow or fall can precipitate a diabetic vitreous hemorrhage, causing sudden vision loss. As noted earlier, a history of previous eye surgeries is important because surgical wounds may be a potential path for extraocular expulsion or wound dehiscence. It is important to know the patient’s level of vision prior to the injury, including whether they wear corrective lenses or contacts. If the patient wears contacts, it is important to know if the patient had them on during the injury. Knowing the overall visual potential of the eye prior to the injury is helpful in setting expectations for the visual prognosis.
Careful exam for a possible open globe injury is crucial, and, notably, this may include limiting the exam. On external exam, close visual inspection of the eyelids, orbit, and surrounding facial structures should first be performed, paying specific attention to any bruising pattern or lacerations on the eyelids and any injury to the lid margins and adnexa.
TABLE 45.1 Terminology for Open Globe Injuries
It is not uncommon for the eyelids to be swollen shut owing to periorbital edema after blunt trauma. An attempt to open the eye may be performed, but extreme care must be taken to avoid applying pressure to the globe during examination, especially in an agitated, frightened, or uncooperative patient. Cavalier handling of the eye during examination in an open globe may result in expulsion of intraocular contents and potentially worsen the injury and prognosis. Measurement of visual acuity, confrontational visual fields, and evaluation of pupillary response and extraocular movements should be performed if possible. Evaluation for a relative afferent pupillary defect (RAPD) is crucial because the presence of an RAPD influences the overall prognosis. A “reverse RAPD” exam can be performed if the pupil is unrecognizable by looking for constriction of the contralateral pupil while light is shone into the injured eye. In a suspected open globe, measurement of IOP via tonometry is not recommended.
Ideally, a standard stationary or portable slit lamp should be used to examine the eye. On anterior segment examination, a full thickness laceration of the cornea or sclera may be readily apparent, with possible wound gaping. Other exam findings that are concerning for an open globe include the following:
Circumferential hemorrhagic conjunctival chemosis (Figure 45.1)
Hyphema, especially if 100% “eight ball” hyphema (indicating dark, clotted blood) (Figure 45.1)
Iris defects (transillumination defects), which may be caused by an intraocular foreign body (Figure 45.2, see black arrow)
Expulsed lens or dislocated intraocular lens and external vitreous humor (sticky, gelatinous texture) (Figures 45.3 and 45.4)
Black, stringy debris (uvea) subconjunctivally or overlying the conjunctiva (Figure 45.4)
Intraocular foreign body (Figure 45.5)
Figure 45.1: Open globe with circumferential hemorrhagic conjunctival chemosis and 8-ball hyphema. A peaked, irregular pupil indicative of early iris expulsion into the globe defect is noted. Additionally, a deflated globe with a flat anterior chamber is present.
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