32 Blunt and Penetrating Ocular Injuries
Ocular trauma is one of the leading causes of visual impairment and monocular blindness in the United States. 1 Of the 2.5 million eye injuries that occur annually, 50,000 result in permanent partial or complete visual loss. 2 There are 55 million eye injuries reported worldwide each year, which result in limitation to daily activities. Of these injuries, 1.6 million are blinding. 3 According to the National Center for Health Statistics’ Health Interview Survey conducted in 1977, approximately 1 million Americans were permanently visually impaired, and 75% of those patients were monocularly blind because of ocular trauma. 4 , 5 The personal, social, and economic impact of this problem is enormous. In recent years, there has been a significant shift of eye injuries from the workplace to the home setting. 2 , 4 However, current estimates of cost burden of eye injuries are still best extrapolated from those occurring in the workplace, due to the higher rate of injury reporting from work settings compared to home settings. 6 , 7 , 8 According to the National Safety Council, the cost of job-related eye injuries (which represents a third of all eye injuries) amounts to $300 million annually. 4 Based on several different reports, in the United States, the average annual rate of eye injury–related visits to an emergency department varied between 2.09 and 3.76 per 1,000 population during the last decade. 7 , 9 , 10 Injury is the leading cause for eye-related hospital admissions. The incidence rate of hospitalized cases for eye injuries (as a primary diagnosis) in the United States is 13.2 per 100,000 annually. 3 , 11 When all direct and indirect costs are included, Occupation Safety and Health Administration reports that, on average, the cost of an eye injury is $1,463. 12 Hospitalization costs secondary to penetrating ocular injuries alone are estimated to be $120 million annually. When personal expense, lost time from work, and social services are included, the financial burden of ocular trauma is immense, with estimates in excess of $1.3 billion annually. 13 Yet, 90% of these injuries are preventable. 4 For example, of more than 600 persons with work-related penetrating eye injuries reported to the National Eye Trauma System Registry between 1985 and 1991, only 6% were wearing safety glasses. 14 This highlights the potential role for the ophthalmologist as an educator and practitioner of preventive medicine.
The majority of ocular trauma occurs in three populations: children, young men, and the elderly. Nearly half (47.6%) of all eye injuries occur in young adults between 18 and 45 years of age. 4 From birth to age 75 years, men have a two to nine times higher risk of sustaining ocular trauma compared to women. Overall, 73% of eye injuries occur in males of all ages. 4 , 11 The incidence of annual hospitalization for patients with the principal diagnosis of ocular trauma as a function of age is bimodal, with one peak occurring between ages 15 and 35 years, and the other occurring after age 70 years. 11 , 13 BB gun use, immature motor skills, and curiosity are common factors that lead to eye injuries in children. Young men most commonly sustain injuries at home, workplace, or as a result of altercations, sports, or motor vehicle accidents. Ruptured surgical eye wounds in the elderly, who are prone to falling, account for 48% of ocular injuries in this population, according to one report. 2 , 7 , 13 Race is also an important risk factor for ocular trauma. Most studies report that nonwhite racial groups are most prone to ocular injuries. One study found that, in the United States, among individuals 25 to 65 years of age, African Americans and Hispanics have a 40 to 60% higher risk of eye injury compared to whites, while a more recent study found that American Indians and African Americans were most prone to ocular injuries. 7 , 15
There are six general categories of trauma that can lead to vision loss:
Intraocular foreign body (IOFB)
This chapter concentrates on the first four categories.
The Ocular Trauma Classification Group has devised a system to classify both closed- and open-globe injuries according to four variables 16 :
Type of injury (based on mechanism).
Grade of injury (defined by visual acuity upon presentation).
Pupil (based on presence or absence of relative afferent pupillary defect [APD]).
Zone of injury (defined by anteroposterior location).
To improve communication among physicians and to increase accuracy in clinical practice and research, a new, internationally standardized classification of ocular trauma terminology, which describes type of injury, has been developed (Table 32-1). 17 The prognosis for visual recovery in each of these categories depends greatly on the ocular structures involved and the extent of the injury. In blunt trauma, damage depends on the tensile strength of the tissues involved. When these limits are exceeded, injury ranges from lid ecchymosis to fractures of the bony orbit or rupture of the globe. In penetrating ocular trauma, the extent of damage depends on the offending object, the site of entry, the depth of penetration, and the number of ocular structures disrupted. Similarly, in perforating trauma, injury depends on the same variables, with the addition of the location of the exit site. In ocular injuries resulting from penetration and retention of IOFBs, the extent of damage depends on the size and type of the foreign body, the velocity on impact, the site of impact, and the intraocular course.
Several studies looked into identifying factors that would be most predictive of visual recovery. Poor visual acuity and a relative APD on presentation have been consistently proven to be most predictive of both functional and anatomical outcome. One retrospective review of penetrating eye injuries demonstrated that eyes with a presenting visual acuity of 20/800 or better were 28 times more likely to achieve a final visual acuity of 20/800 or better compared to eyes presenting with a visual acuity of less than 20/800. 18 In another study, only 3% of eyes presenting with hand motions vision or better underwent enucleation, versus 39 to 89% of eyes presenting with light perception or no light perception visual acuity, respectively. 19 With respect to the presence or absence of an APD, a multivariate analysis of 240 traumatized eyes found that 69% of eyes without an APD achieved a final visual acuity of 20/200 or better, compared to 34% of eyes with an APD. 20 A recent retrospective study of patients with open-globe injuries requiring vitrectomy showed that presence or absence of an APD was a significant predictive factor for visual outcome, while retinal detachment on initial presentation was predictive of anatomical outcome. 21
The zones of eye injury were defined based on review of operative reports of open-globe repair and were grouped as such: zone I (cornea and limbus), zone II (anterior sclera within 5 mm of the limbus), and zone III (sclera 5 mm posterior from the limbus). 16 , 22
The most recent advancement in predicting visual outcome in traumatized eyes comes from the development of an ocular trauma score (OTS) in 2002 by Kuhn et al. The authors analyzed 2,500 eye injuries and 100 variables. After statistical analysis, six variables were found to have prognostic significance in predicting long-term visual acuity in an injured eye. Each variable was assigned a raw point value and, based on the numerical sum of those points, an OTS on a scale from 1 to 5 was developed (Table 32-2 and Table 32-3). Based on OTS, the physician can counsel the patient and family regarding triage, management, and expectations; decrease anxiety and some elements of uncertainty; and plan, evaluate, and reassess interventions in a standardized fashion. 23
32.2 History and Examination
As with any medical emergency, the stability of the patient takes first priority. Because one-third to one-half of ocular injuries are associated with concomitant nonocular injuries, 24 , 25 a general neurologic and systemic examination, including assessment of vital signs, mental status, cardiac and pulmonary function (to rule out chest trauma), and the extremities (to rule out fractures), should be performed initially. For example, an elderly patient with previously normal mental status appeared in our emergency department confused after falling and sustaining blunt trauma to the eye and orbit. Although she had an open globe, her expanding subdural hematoma took medical precedence over any ocular damage. When it has been determined that other critical systems are stable and/or uninvolved, it is safe to proceed with the ophthalmic evaluation.
One-third to one-half of ocular injuries are accompanied by nonocular injuries. A comprehensive systemic evaluation is an important part of the initial work-up.
A detailed history of the injury is an essential part of the initial evaluation; it helps to guide management and clarify any medicolegal issues that may arise later. Important questions include the following:
How did the injury occur (e.g., hammering metal on metal)?
When did the injury occur?
Where did the injury occur (e.g., work-related)?
Was the patient wearing protective eyewear, glasses, or contact lenses?
What emergency measures were taken (e.g., irrigation, tetanus, antibiotics)?
Is there a possible IOFB?
When was the patient’s last meal (to time surgical intervention)?
Examination of both eyes should proceed with due caution. Excessive pressure on an open globe may result in extrusion of intraocular contents and further damage. The most critical components of the initial ocular examination are the visual acuity and pupillary examination for the reasons mentioned in the previous section. Careful external and slit-lamp examination can reveal orbital or facial bony abnormalities, subdermal air (crepitus), entry wounds, hyphema, lens rupture, prolapsed uvea or vitreous, and other anterior or posterior segment pathology. However, opening the lids of an uncooperative patient, such as a child or an inebriated patient, should be deferred until the patient is under anesthesia. The intraocular pressure should be measured in all cases unless there is an obvious anterior rupture site. If visualization of the lens, vitreous cavity, and retina is prevented by a miotic pupil, sterile dilating drops may be used to achieve mydriasis. The more information obtained during this initial examination, the better equipped the physician will be to make management decisions and plan any surgical intervention that may be needed.
32.3 Ancillary Tests
Ancillary tests, particularly various imaging modalities, are often used to help guide the timing or type of any necessary invasive procedure (Table 32-4). The single most useful test in the initial evaluation of the ocular injury is computed tomography (CT). The physician ordering a CT scan should specify that the study include 1- to 1.5-mm axial and coronal cuts through the orbits and chiasm. If a small foreign body is suspected, overlapping slices may be requested. 26 CT can localize foreign bodies (Fig. 32-1) and demonstrate scleral abnormalities and intraocular blood, and is the best imaging study for bones (Fig. 32-2). However, bone-free projections are used to detect small radiolucent foreign bodies. 27 In an experimental study, investigators implanted 21 metallic and nonmetallic foreign bodies in bovine eyes. 28 Except for polymethyl methacrylate intraocular lens (IOL), all objects (including glass, ceramic, metals, wood, stone, and porcelain) were visualized on CT. However, six of the objects (all metals) appeared 50 to 100% larger than their true size.
The single most useful ancillary test in the initial evaluation of ocular injury cases is CT.
CT has two main limitations. The first is that beam hardening (or scattering) artifact from metal may make exact localization or characterization of a metallic foreign body difficult. The second is that plastic and wood foreign bodies are low in Hounsfield units (similar to air) and, therefore, may not be apparent on CT.
32.3.1 B-scan Ultrasonography
B-scan ultrasonography is another useful imaging modality. It has resolution capabilities of up to 1 mm. Echographic examination is primarily useful in evaluating the lens and posterior segment when direct examination is precluded by media opacities (Fig. 32-3). Ultrasonography is reliable in detecting vitreous incarceration, choroidal detachment, vitreous hemorrhage, vitreous separation, retinal tears and detachment, and areas of vitreoretinal adhesion. It is particularly useful in determining whether a small foreign body lies within or immediately outside the eye. A retrospective study of 46 eyes presenting with penetrating ocular injuries compared the preoperative echographic findings with the intraoperative findings. Echography proved 100% accurate in identifying retinal detachments, IOFBs, choroidal hemorrhages, and the presence of a posterior exit site, but posterior extensions of anterior lacerations were missed in 25%. 29 Echography can also detect the presence or absence of a lens, lens rupture or dislocation, and cyclitic membranes. Unfortunately, occult posterior scleral ruptures are often difficult to detect. Echographic clues such as incarcerated vitreous (Fig. 32-4), retinal thickening or detachment, irregular scleral contours, decreased scleral reflectivity, and episcleral hemorrhage in the adjacent space may support a suspected diagnosis of scleral rupture. When the globe is open, echographic examination must be performed very gently and through closed lids, which can limit the resolution power. The usefulness of echography is also limited by shadowing caused by highly reflective surfaces such as air, reverberation artifacts created by some IOFBs, and the extent of the user’s skill and familiarity with ocular pathology. 30
With an open globe, it is usually best to defer ultrasonographic examination until after the rupture site has been repaired. If an IOFB is suspected in this setting, CT should be used instead.
32.3.2 Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) has also been used in the evaluation of ocular trauma. Although the quality of MRI is excellent, it cannot image bone or metallic objects. Further, the magnetic fields and heat generated during MRI scanning preclude examination of patients with potential intraocular or intraorbital metallic foreign bodies. Investigators have shown that ferromagnetic foreign bodies implanted in animal eyes can move 7 to 8 mm in the suprachoroidal space and up to 10 mm in the vitreous space when subjected to the torsional forces of MRI. 28 In addition, retained intraocular ferromagnetic foreign bodies cause surrounding image distortion, making the globes themselves difficult to visualize. Image distortion can similarly occur from the paramagnetic effects in granite, solder, and mascara. The principle advantage of MRI over CT scan is that the former provides superior imaging of intraocular structures, accurately and safely detects vegetable, plastic, glass, and other radiolucent foreign bodies, and is safe during pregnancy.
32.3.3 Plain Roentgenograms
Plain roentgenograms are useful imaging studies to characterize the number and shape of metallic foreign bodies (Fig. 32-5). Often, roentgenography is the first imaging study performed when the question of a foreign body exists. However, plain x-ray films may not detect nonmetallic objects or accurately determine whether objects are intraocular or intraorbital. Because of these limitations, many surgeons do not routinely use plain films and instead proceed directly to CT to expedite the initial evaluation.
32.3.4 Flash Visual Evoked Potential
Flash visual evoked potential (VEP) studies have been used as a prognostic examination. VEP is a measure of mass retinal response, providing information on central visual function. Patients with ocular trauma and normal VEP findings have been shown to have a mean visual acuity outcome of 20/100. In contrast, those with an absent response had a mean visual acuity of hand motions. 31 In the setting of a ruptured globe, this test would be performed after the eye has undergone the primary repair. Unfortunately, this test is not available in most eye centers.
Electroretinogram (ERG) can be used to gauge the visual potential of an injured eye in the setting of a nonverbal patient. It can also be used to assess retinal toxicity if a metallic intraocular or intraorbital foreign body is present. 27 In one study, the authors suggest that use of ERG and VEP within 2 weeks after primary severe eye injury repair may guide further intervention such as major reconstruction or enucleation to avoid sympathetic ophthalmia. 32
32.4 Preoperative Management
For known or suspected ruptured globe cases, the primary surgical procedure should be performed as soon as possible. In preparation for surgery, the preoperative management includes the following:
Nothing by mouth
Rigid shield over the involved eye
No narcotics or sedatives
Antiemetics as needed
Broad-spectrum intravenous antibiotics
Updated tetanus immunity
Notification of the operating team
Serum electrolytes, blood urea nitrogen, and creatinine
Screening for human immunodeficiency virus, sickle cell, hepatitis, drugs, and alcohol
Possible imaging (e.g., CT)
32.5 Blunt Trauma
In an urban setting, 60% of all eye injuries are caused by blunt trauma. 13 The etiologic object in blunt trauma does not penetrate the eye but may result in a variety of ocular injuries, including corneal abrasion, hyphema, iridodialysis, cyclodialysis, a dislocated or ruptured lens, vitreous hemorrhage, commotio retinae, sclopetaria, retinal tear or detachment, choroidal rupture, scleral rupture, and avulsion of the optic nerve (Fig. 32-6). The damage incurred is a result of either direct tissue compression by the object or indirect tissue disruption by the resultant shock.
32.5.1 Commotio Retinae
Commotio retinae is a frequent complication of blunt trauma. It can occur in any retinal location but is most prominent in the posterior pole, where it is termed Berlin’s edema (Fig. 32-7). Clinically, commotio retinae appears as outer retinal whitening that is evident shortly after the injury. When the macula is involved, a cherry-red spot may be present, and visual acuity may be reduced to 20/200. Fluorescein angiography findings are usually normal, without leakage of fluorescein dye; however, breakdown of the outer blood–retinal barrier with leakage at the level of the retinal pigment epithelium (RPE) has been documented. 33 The retinal opacification was originally thought to be a form of retinal edema 34 ; however, experimental and histopathologic studies have shown that it is the result of photoreceptor cell outer segment disruption and, perhaps, also some degree of damage to the RPE. 35 , 36 , 37 During the last decade, wide utilization of optical coherence tomography confirmed that the major site of retinal damage appears to be at the level of photoreceptor outer segments. 38 , 39 Typically, the retinal transparency and vision normalize within 4 days to 4 weeks of the injury as the photoreceptor outer segments regenerate. Although the prognosis for visual recovery is good, complete visual recovery occasionally does not occur, and this may be a result of underlying RPE damage or sometimes even secondary macular hole formation, the latter of which may be amenable to surgical repair.
32.5.2 Choroidal Rupture
When compression injury to the globe is sufficient, choroidal rupture(s) can result. Most often, the rupture is located posteriorly and is classically crescent-shaped and in an orientation concentric to the optic nerve head (Fig. 32-8). Specifically, the injury represents rupture of the relatively inelastic Bruch’s membrane and adjacent structures—that is, the overlying RPE and underlying choriocapillaris. Neurosensory retina, outer choroid, and sclera are intact. Of note, patients with angioid streaks are particularly vulnerable to choroidal rupture secondary to a brittle Bruch’s membrane. 40 The curvilinear rupture site is yellow-white, but initially it may be obscured, at least in part, by subretinal and or sub-RPE hemorrhage. The associated blood at presentation is derived from the disrupted choriocapillaris. With time, the blood resorbs and varying degrees of surrounding RPE atrophy, RPE clumping, or subretinal fibrosis can be seen. 41
Choroidal ruptures often occur in the macula and, in this location, usually result in some degree of decreased vision immediately (Fig. 32-9). However, if the rupture is not directly under the fovea, either the vision is not affected or spontaneous visual improvement can occur once the adjacent thin layer of subretinal hemorrhage resorbs. Goldman et al reported successful pneumatic displacement of submacular hemorrhage associated with traumatic choroidal rupture with good visual recovery. 42 Late visual acuity loss can occur due to secondary choroidal neovascularization (CNV) at the edge of the rupture site (Fig. 32-8). One study determined that proximity of the choroidal rupture site to the center of the fovea and its length serve as risk factors for development of CNV in traumatic choroidal ruptures. 43 Therefore, patients who initially have relatively good vision should be followed up regularly for the development of this complication, as early detection of CNV may allow for injections of anti–vascular endothelial growth factor medication or focal laser to help preserve vision (Fig. 32-10).
32.5.3 Retinitis Sclopetaria
A concussive, nonpenetrating injury to the eyewall can sometimes cause disruption of both the retina and choroid, producing a clinical picture known as retinitis sclopetaria or chorioretinitis sclopetaria. This classically follows high-velocity missiles striking the orbit and traveling in close proximity to the eyeball, with the affected area usually located adjacent to the path of the missile (direct or coup injury) and in the posterior pole (indirect or contrecoup injury) caused by shock waves transmitted across the globe. On examination, those lesions frequently appear to coalesce. 44 Shock waves generated by the missile in the orbit are thought to be the primary mechanism of injury. Acutely, the ophthalmoscopic findings consist of large retinal breaks; surrounding areas of retinal opacification; subretinal, intraretinal, or vitreous hemorrhage; and areas of visible sclera. Initially, blood may dominate the clinical picture and obscure the retinal or choroidal disruption at first. As the blood resorbs, extensive chorioretinal scarring, typically with irregular, “clawlike” edges, becomes evident (Fig. 32-11). Because the fibrosis often completely fuses the tissues around the retinal breaks, retinal detachment rarely occurs. Therefore, observation is all that is necessary in most cases. Should any retinal breaks appear not to be sealing down, however, laser or cryotherapy should be performed. If retinal detachment occurs, it is usually from another site.
32.5.4 Vitreous Hemorrhage
Among all patients presenting to an urban general eye clinic with vitreous hemorrhage, trauma was the underlying etiology in 18% of cases. 45 In patients younger than 40 years, trauma is the leading cause of vitreous hemorrhage. 45 Vitreous hemorrhage caused by blunt trauma results from damage to vessels of the ciliary body, retina, or choroid. The degree of hemorrhage varies but is usually visually significant, resulting in a visual acuity of 20/200 or worse in 74% of eyes. 45 Initially, the hemorrhages are often compartmentalized within a portion of the vitreous gel or in the subhyaloid space. Therefore, at the first examination, the location or configuration of the vitreous hemorrhage may provide clues to the origin. Particular attention should be paid to the peripheral fundus, with a search for retinal tears and detachments. The vitreous blood may eventually diffuse throughout the vitreous cavity, obscuring follow-up funduscopic examination. If a rupture site is evident or suspected, a depressed fundus examination should be deferred. If an adequate examination of the fundus cannot be performed, an echographic examination should be performed. Echography can accurately detect retinal detachments, posterior vitreous detachments, and choroidal detachments. Retinal tears (without detachments) can also be seen, but small peripheral breaks may be missed; therefore, the lack of a retinal tear on ultrasonography does not rule out its presence. As mentioned earlier, occult scleral ruptures can be difficult to diagnose with ultrasound.
With a traumatized globe and significant media opacity, B-scan ultrasonography can detect retinal detachments and many retinal tears, but small peripheral retinal breaks and occult scleral ruptures can be missed.
The clinical information obtained from the examination and echography will direct management. In the absence of retinal tear or detachment, the patient should initially be observed with serial fundus and echographic examinations every 3 to 4 weeks. Bedrest with the patient’s head elevated (30 degrees) at all times may facilitate clearing or settling of the vitreous blood. If a retinal tear is seen ophthalmoscopically, laser or cryotherapy should be performed to minimize the risk for subsequent retinal detachment. If a retinal tear is noted on ultrasound, it can be followed weekly with serial ultrasound examinations. During the follow-up period, the hemorrhage may clear and allow treatment. Some authors report success with ultrasound-guided cryopexy in patients with opaque media secondary to vitreous hemorrhage. 46 , 47 If a retinal detachment occurs, or if the hemorrhage is visually significant and does not clear within a few months, a standard three-port pars plana vitrectomy, with or without a scleral buckle, should be performed.