Mechanical ophthalmic trauma may be produced by objects that are blunt, sharp, or a combination of the two, and can be categorized into closed and open globe injuries, eyelid wounds, and orbital injuries, but these may co-exist, in which case coordination of management with maxillo-facial surgeons is important.
Corneal abrasion, which is one of the most common ophthalmic injuries encountered in an urgent care or emergency room setting, occurs when the corneal epithelium is disrupted, usually by a tangential impact such as from a fingernail or edge of a piece of paper. The patient typically complains of severe discomfort with foreign body sensation, profuse tearing, inability to keep the eyelids open, and impaired vision. If initial examination shows no obvious corneal laceration, topical anesthetic drops can be instilled, usually resulting in rapid reduction in discomfort and easier examination. Instillation of fluorescein highlights the corneal epithelial defect, which is usually in the inferior cornea, by staining the exposed basement membrane (Figure 19–6). If instead, there is curvilinear staining of the superior cornea, a subtarsal foreign body should be suspected (see later in the chapter).
Corneal abrasion is treated by instillation of an antibacterial ointment and patching of the eye. The patient is instructed to remove the patch, and apply antibacterial ointment and another patch, 2 to 4 times daily until the eye is comfortable. The patient can be reexamined periodically during the healing period to ensure that microbial infection has not developed, and certainly should be reexamined if symptoms do not settle within a few days or increase. Under no circumstance should topical anesthetic drops be provided or prescribed for the patient's use, because they delay corneal epithelial healing, mask progression of disease, and if used for a prolonged period can cause a persistent neurotrophic corneal epithelial defect.
Corneal foreign body occurs when a small particle, usually with sharp rather than smooth edges, strikes the eye with insufficient momentum to cause it to pass completely through the cornea but sufficient for it become embedded within it. Alternatively, the particle may become embedded in the conjunctival surface of the upper eyelid (subtarsal foreign body). Symptoms are similar to those of a corneal abrasion, but usually not as severe and with predominance of foreign body sensation with eye opening and closing. Depending on its size, color, and transparency, metal being easier to detect than untinted glass, a corneal foreign body may be visible on diffuse flashlight examination of the ocular surface (Figure 19–8), but slitlamp examination is definitive. If examination is negative, the upper eyelid should be everted to detect any subtarsal foreign body (see Chapter 2), which usually can be removed by wiping the conjunctival surface with a sterile cotton bud, the only other required treatment being a single instillation of antibacterial ointment.
Metallic corneal foreign body appearing as dark brown speck on the cornea (arrow).
Emergency room staff trained in slitlamp examination can remove corneal foreign bodies, otherwise the patient should be referred to an ophthalmologist. The cornea should be anesthetized with topical anesthetic drops. Before attempting to remove a corneal foreign body, it must be confirmed by slitlamp examination that it is superficial and does not extend completely through the cornea, in which case removal should be performed by an ophthalmologist, generally in an operating room with an operating microscope so that tissue glue can be applied or sutures inserted if necessary. A superficial corneal foreign body can usually be removed at the slitlamp, using the tip of a sterile (18 or 21 gauge) needle. Iron or copper foreign bodies usually produce a ring of chemical tissue staining (“rust ring”), which can be scraped off with the needle tip or removed with a burr tip on a battery-operated drill. Following removal of a corneal foreign body, antibacterial ointment is instilled and the eye is patched. The patient is instructed to remove the patch, and apply antibacterial ointment and another patch, 2 to 4 times daily until the corneal epithelial defect has healed. The patient should be reexamined periodically during the healing period to ensure that microbial infection of the defect has not developed.
Subconjunctival hemorrhage of limited extent is common after ocular or orbital blunt injury (Figure 19–9). Extensive hemorrhagic chemosis, especially if the eye is soft or collapsed indicating low intraocular pressure, is strongly suggestive of globe rupture (Figures 19–3 and 19–4), and urgent surgical exploration is required (see later in the chapter).
Post-traumatic hyphema and associated subconjunctival hemorrhage.
Most conjunctival lacerations and partial-thickness corneal, and/or scleral lacerations can be managed like a corneal abrasion. Following slitlamp examination to ensure that any corneal or sclera laceration is not full-thickness, antibacterial ointment is instilled and the eye is patched. The patient is instructed to remove the patch, and apply additional antibacterial ointment and patch the eye 2 to 4 times daily until the laceration has healed. The patient should be reexamined periodically during the healing period to ensure that microbial infection of the wound has not developed.
Traumatic iritis frequently develops after closed globe injury. Symptoms include pain, especially in bright light, blurred vision, and tenderness of the globe. Slitlamp examination reveals inflammatory cells and flare in the anterior chamber, and finely dispersed cellular keratic precipitates on the corneal endothelium. There may be a (Vossius) ring of dark brown iris pigment on the anterior lens capsule. Posterior synechiae and peripheral anterior synechiae may develop. Treatment consists of cycloplegic mydriatic drops (eg, cyclopentolate 1% or atropine 1% twice a day) and topical corticosteroid drops (eg, dexamethasone 0.1%) 2 to 4 times a day until the intraocular inflammation subsides.
Traumatic hyphema (anterior chamber hemorrhage) (Figure 19–9) reflects damage to iris blood vessels, and may be associated with iridodialysis or cyclodialysis (see later in the chapter). It should always raise concern about open globe injury (Figure 19–1). It may be short-lived and resolve spontaneously, but it can be complicated by secondary glaucoma and corneal blood staining, particularly if there is recurrence of hemorrhage. Depending on the extent of the hyphema and the severity of any other ocular damage, treatment ranges from restriction of activities to reduce the risk of rebleeding until the hyphema has resolved, to hospitalization with medical therapy (topical, oral, or even intravenous) to control intraocular pressure, and possibly anterior chamber washout. Oral aminocaproic acid reduces the risk of rebleeding. Aspirin and non-steroidal anti-inflammatory drugs (NSAIDS) should be avoided. The consequences of hyphema are more serious in sickle cell disease.
The concussive shock wave of blunt ocular trauma can result in small radial tears in the iris sphincter muscle at the pupillary margin (iris sphincter ruptures), localized or extensive circumferential tearing of the iris at the iridociliary junction (iridodialysis), or even a localized or extensive circumferential separation of the peripheral iris and ciliary body from the sclera at and behind the scleral spur (cyclodialysis). Such defects may not be apparent initially if accompanied by hyphema. Because cyclodialysis allows increased drainage of aqueous into the suprachoroidal space, it frequently results in low intraocular pressure (hypotony). Ultrasound biomicroscopy is useful for identifying cyclodialysis and associated ciliochoroidal effusion in hypotonous eyes.
Traumatic anterior chamberangle recession is circumferentially oriented tearing of the trabecular meshwork tissue. It is also frequently accompanied by hyphema and may not be evident until any blood clears from the anterior chamber. It may be detectable by gonioscopy or ultrasound biomicroscopy. It is important that eyes that have sustained significant blunt trauma, particularly if there has been hyphema, undergo gonioscopy to detect angle recession because its presence provides information on the likelihood of subsequent glaucoma, which may occur from structural damage and/or impairment of trabecular meshwork function.
Traumatic lens dislocation (subluxation) due to damage to the zonules may manifest as instability of the crystalline lens (phakodonesis), often more evident on slitlamp examination as abnormal quivering movements of the iris (iridodenesis) on rapid rotation of the globe, or prolapse of vitreous into the anterior chamber. The entire lens may be dislocated posteriorly into the vitreous or (rarely) anteriorly into the anterior chamber. Lens dislocation may be associated with subsequent development of glaucoma, largely reflecting the severity of the ocular trauma resulting in trabecular meshwork damage but also possibly due to blockage of flow of aqueous through the pupil (pupillary block).
Cataract may be a delayed consequence of blunt ocular trauma and usually can be managed with conventional surgical techniques with insertion of a posterior chamber intraocular lens, but the surgery may be complicated by lens instability due to zonular damage. An uncommon entity is traumatic posterior lens capsule rupture, usually requiring early surgery with specialized techniques.
Commotio retinae is a characteristic pattern of retinal whitening that occurs after severe closed globe ocular contusion. It generally develops 180° opposite the site of impact, the shock wave travelling posteriorly in the eye to strike the fundus (contrecoup injury). The retinal whitening typically appears within 24 hours and gradually fades over several days to weeks. If the macula is affected, visual acuity may be profoundly reduced.
Choroidal rupture is tearing of the retinal pigment epithelium, characteristically in a crescentic or curvilinear shape orientated tangentially to the optic disc margin, after closed globe ocular contusion (see Chapter 10). Involvement of the central macula, which commonly occurs, usually results in profound and permanent reduction of visual acuity. There is also a risk of subsequent choroidal neovascularization, but this is usually amenable to treatment.
Full-thickness macular hole (Figure 19–10) may follow severe closed globe contusion injury in which the shock wave is transmitted directly to the fovea. The hole usually develops acutely as separation of vitreous adherent to the macula pulls off an operculum of full-thickness retina in the foveal region. The hole can sometimes be closed by vitreo-retinal surgery, but visual acuity frequently does not improve.
Post-traumatic macular hole (larger arrow) with surrounding serous subretinal fluid (smaller arrow).
Closed globe ocular injuries frequently result in vitreous hemorrhage, which may be mild to severe. The usual mechanism is partial to complete posterior vitreous detachment with tearing of superficial retinal blood vessels in areas of particularly firm vitreo-retinal adhesion. As long as there is no retinal tear, the intravitreal blood usually clears spontaneously within a few weeks to months. If the retina is torn, retinal detachment frequently develops, requiring surgical reattachment that commonly necessitates vitrectomy.
Open globe injuries are characterized by full-thickness wound of the cornea and/or sclera, resulting in exposure or extrusion of intraocular contents. They are divided into perforating ocular lacerations and globe ruptures.
Perforating Ocular Lacerations
A perforating ocular laceration (penetrating ocular trauma) may be caused by a sharp object that enters the globe and
is then instantaneously or subsequently withdrawn prior to the patient's presentation, such as glass, wire, or the blade of a knife or scissors, that is, single wound without a retained intraocular foreign body,
passes completely through it and then lodges in the orbit, such as a metallic foreign body, or then is withdrawn, such as a hypodermic needle for administration of local anesthetic injection for cataract surgery, that is, separate entry and exit wounds (double ocular perforation) without a retained intraocular foreign body, or
remains completely or partially inside the globe, that is, retained intraocular foreign body.
Ocular lacerations without a retained intraocular foreign body (Figures 19–1 and 19–2) represent the most common type of open globe injury encountered in most trauma centers. As discussed above, as soon as the laceration is recognized, the injured eye is protected with an eye shield; analgesia, and possibly antiemetic medication to reduce the chance of vomiting, and if necessary tetanus toxoid, are administered; and orbital CT scan is performed to exclude any ocular or orbital foreign body and to provide further information about the extent of damage to the globe. Systemic antibiotics are administered if there is involvement of the sclera, or extensive anterior segment damage.
Urgent exploration under anesthesia (usually general but possibly local supplemented if necessary with intravenous sedation) is then undertaken. (Double ocular perforation with a hypodermic needle may be self-sealing and not require urgent exploration, but later may require vitreo-retinal surgery to manage retinal complications or remove vitreous hemorrhage.)
Whenever possible, it is crucial that the full extent of the wound is determined; if necessary, by opening the conjunctiva through 360° and detachment of rectus muscles, because failure to identify and close the ends of the wound will usually lead to postoperative hypotony and increases the risk of endophthalmitis. Once the wound has been fully exposed, any prolapsed uveal tissue and retina are identified, with a view during closure of the laceration to replacing (repositing) them within the globe, as long as they are not dirty, dessicated, or necrotic, in which case the externalized portions are abscissed. Prolapsed vitreous is abscissed. The crystalline lens may be intact, absent, or damaged, the last possibly requiring aspiration of lens material or deferral of specific treatment until a later procedure (see later in the chapter).
The laceration is sutured as accurately as possible, with particular attention to the limbus if it is involved and to avoidance of sutures being placed across the visual axis of the cornea, as well as avoidance of incarceration of corneal or conjunctival epithelium. Corneal lacerations are usually closed using 10–0 nylon sutures with buried knots, scleral lacerations with 8–0 or 9–0 nylon sutures, and conjunctival wounds with absorbable 7–0 or 8–0 sutures. At the end of the repair, the wound should be watertight. If the globe is soft, sterile isotonic saline solution is injected into the anterior chamber or vitreous cavity to restore the ocular shape and volume. Subconjunctival antibiotic is administered, or if there is involvement of the posterior segment, particularly if the mechanism of injury suggests a high risk of infection or presentation was delayed, intravitreal antibiotic may be administered. A sterile eye patch and protective eye shield are applied.
On the following day, topical antibiotic, steroid and cycloplegic/mydriatic are started. The patient should be reexamined frequently to identify wound leaks, corneal ulceration, intraocular infection (endophthalmitis), recurrent intraocular bleeding, hypotony, or ocular hypertension that may require additional interventions. Many eyes with a scleral wound require vitreo-retinal surgery because of retinal complications, usually related to incarceration of vitreous into the wound and the development of vitreo-retinal traction. Corneal scarring may require penetrating keratoplasty (corneal transplantation), assuming that other complications such as glaucoma or retinal damage have not rendered it inappropriate.
If exploration shows so much damage that suturing of the globe is not feasible (eg, in some gunshot wounds and shrapnel injuries), primary removal of the globe is probably appropriate. Traditionally enucleation rather than evisceration is advised to maximize removal of uveal tissue, and thus reduce the risk of sympathetic ophthalmia (see Chapter 7), but studies indicate that there is no difference in risk and evisceration is associated with fewer complications. Similarly, in eyes that have undergone primary repair but have no perception of light, the conventional treatment is enucleation within 10 days of the initial injury to reduce the risk of sympathetic ophthalmia, but the availability of effective treatments for sympathetic ophthalmia and its rarity, the better cosmetic outcome if the globe is retained, and the possibility of recovery of vision following vitreo-retinal surgery, have led to a questioning of this approach.
Ocular lacerations associated with one or more retained foreign bodies (eg, an embedded fishhook, a sliver of glass, a portion of the casing of an exploded firework, or a metallic fragment generated by striking metal on metal) (Figure 19–11) must be managed on an individual basis, taking into account the type of foreign body, its size, its anatomic location, the extent and severity of the globe laceration, and availability of surgical expertise and instrumentation such as for vitrectomy. Foreign bodies that project partly in and partly out of the eye (eg, an embedded fishhook or wire) (Figure 19–5), can usually be removed during the primary surgery. For foreign bodies that are completely inside the eye and cannot be visualized adequately intraoperatively, for instance because of intraocular blood or lens opacity, or cannot be removed successfully without strong probability of avoidable additional intraocular damage, for instance because of lack of appropriate expertise or instrumentation, generally attempted removal should be deferred until a subsequent procedure. Whereas magnets were previously used to remove magnetic intraocular foreign bodies, removal with forceps, which can also be used for non-magnetic foreign bodies, is now preferred. High-velocity metallic foreign bodies are usually sterile with a low risk of endophthalmitis, whereas other foreign bodies, particularly wooden, are associated with higher risk of endophthalmitis, and intravitreal antibiotics may be administered at the time of the initial and/or subsequent surgery.
Metallic foreign body lying on the surface of the retina.
In many cases of corneal or corneoscleral laceration, the lens is retained but its anterior capsule is damaged, leading to hydration of lens matter that will usually progress over the ensuing days and caused marked intraocular inflammation. Occasionally, it is possible or necessary to aspirate the lens matter at the time of initial repair, but frequently it is deferred until a second operation, when there is more information about the extent of ocular damage, including whether vitreo-retinal surgery is required, and there is likely to be better visualization of the anterior segment. Whether an intraocular lens can be inserted will depend upon several factors, including whether sufficient posterior capsule has been retained and how much iris has been lost.
In some instances of corneal or corneoscleral laceration, the crystalline lens is extruded from the eye. The expulsed lens may be identified or its absence noted during surgery, but in most cases the eye is found to be aphakic at postoperative slitlamp or ultrasound examination.
Globe rupture refers to a breach of the integrity of the globe due to forceful indentation by blunt trauma, such as from a punch, particularly if the assailant is wearing a bulky ring. Relatively common sites are the limbus, the sclera beneath the insertion of the extraocular muscles (especially in the superonasal quadrant), and at prior incision sites (eg, at the interface between donor and recipient cornea following penetrating keratoplasty). Globe rupture should be suspected in any blunt ocular trauma associated with massive hemorrhagic chemosis, especially if the eye is soft or collapsed indicating low intraocular pressure (Figures 19–3 and 19–4). Whenever globe rupture is suspected, urgent surgical exploration is required. The pre-, per- and postoperative management is broadly the same as for perforating ocular laceration without foreign body, except that preoperative CT scan may not be deemed necessary if the history clearly does not suggest a risk of intraocular foreign body.
Lacerations and tears of the eyelids are a common type of ophthalmic injury, occurring in a wide variety of situations, such as automobile accidents, fights, impacts by blunt or sharp projectiles, falls, animal bites, and explosions. The most important step in management is thorough examination to determine the precise location, depth, and extent of the wound, whether there is embedded foreign material, and to detect all relevant associated ocular and orbital injuries, including involvement of the lacrimal drainage system. Whenever there is a full-thickness eyelid laceration, the possibility of open globe injury must be borne in mind (Figures 19–1 and 19–12).
Full-thickness laceration of medial left lower eyelid involving the margin with underlying scleral laceration with uveal prolapse.
All wounds need to be thoroughly debrided, with removal of as much foreign material as possible. Prophylactic systemic antibiotics should be considered for animal bites and dirty wounds, particularly if there is a delayed presentation. Superficial wounds that do not involve the eyelid margin or medial canthal region should be repaired in the same way as skin wounds elsewhere. Full-thickness wounds that involve the eyelid margin require specialist repair to ensure correct realignment of the tarsal plate, mucocutaneous junction, and lash line. Involvement of the medial canthal region warrants microsurgical exploration, to allow repair of torn or lacerated lacrimal canaliculi, commonly by insertion of a lacrimal stent, and reconstruction of the medial canthal tendon, to reduce the likelihood of epiphora and to limit cosmetic abnormality.
Contusion of the orbital soft tissues, resulting from blunt injury such as from a punch, batted baseball, or fall, may be associated with eyelid wounds, ocular injuries, or orbital fractures. The most common manifestation is orbital swelling, possibly with proptosis, and eyelid ecchymosis (Figure 19–13). There may be limitation of eye movements. If there is severe proptosis with corneal exposure or visual loss due to optic nerve compression, usually due to orbital hemorrhage, lateral canthotomy and cantholysis may be performed as an emergency procedure. Orbital CT can also be undertaken to identify whether there is an orbital hematoma suitable for surgical evacuation. If there is no corneal exposure or optic nerve compression, no treatment except analgesics and cold compresses is usually needed.
Prominent right eyelid ecchymosis and subconjunctival hemorrhage due to blunt trauma suffered in a fall.
Orbital fractures (Figure 19–7) are a common consequence of mechanical trauma, with involvement of one or more of the bony walls and/or the anterior rim, possibly extending to a tripod fracture involving the zygoma (malar eminence) or even a Le Fort II or III fracture, by a combination of shock waves and shearing forces. Clinical signs include orbital swelling and eyelid ecchymosis, depression of the malar eminence, step-off defect on palpation of the orbital rim, numbness in the distribution of the infraorbital nerve that traverses the orbital floor, crepitus on palpation indicating the presence of intraorbital air, enophthalmos but this may not be present initially if there is orbital soft tissue swelling, and restricted ocular motility. Orbital CT provides confirmation. Mid-facial or head trauma, such as from automobile accidents or severe falls or assaults, that results in orbital fracture is commonly associated with other fractures of the face or of the vault or base of the skull. Appropriate further imaging should be undertaken to identify such fractures, as well as potentially life-threatening intracranial or other injuries, and consultation obtained from neurosurgeons and maxillo-facial surgeons as necessary.
Most orbital rim and wall fractures do not require immediate surgical repair. Exceptions are orbital wall fractures with entrapment of an extraocular muscle that is complicated by recurring profound bradycardia (due to a persistent oculocardiac reflex from the entrapped muscle), the trapdoor variety of orbital floor fracture that usually occurs in children and may be accompanied by nausea and vomiting, and possibly profound acute visual loss due to a bone fragment impinging on the optic nerve in the posterior orbit or optic canal, but the benefit from surgical exploration in this situation is not well established. Otherwise, surgery can usually be delayed for one to two weeks to allow the soft tissue swelling to diminish, determination whether surgery is required, and management of any globe injuries. The indications for repair of orbital floor fractures are enophthalmos, extensive fracture that is likely to result in the development of enophthalmos, and troublesome diplopia due to entrapment of orbital soft tissue, possibly including the inferior rectus muscle, which is not spontaneously improving. Repair is accomplished by elevating the periosteum over the defect, freeing entrapped tissue, removing or replacing displaced fragments of bone, and closing the defect such as with an alloplastic plate. Further surgery may be needed to manage persisting strabismus or ptosis, the latter usually being due to damage to the levator muscle. Displaced zygomatic arch fractures generally require surgery.
Some eyelid wounds extend deep into the orbit, resulting in damage to the extraocular muscles, lacrimal gland, orbital blood vessels and nerves, and possibly the optic nerve. Most fully embedded orbital foreign bodies, except perhaps those that are known to have been grossly contaminated or composed of organic material such as wood, do not need to be removed, unless they result in orbital infection.
Optic nerve injury (see Chapter 14) may occur in orbital wounds, including local anesthetic injections for ocular surgery, or indirectly following blunt trauma to the forehead without fracture due to transmission of shock waves to the orbital apex, but most commonly occurs with severe head or facial injury with fracture involving the optic canal or posterior orbit. Although in the last situation high-dose systemic steroid therapy and optic canal decompression have been advocated, there is little evidence that either is beneficial. Surgery may be indicated for orbital hemorrhage. Optic nerve avulsion characteristically occurs after abrupt rotation of the globe, such as from the eye being poked forcibly with a finger and has a poor prognosis with no effective treatment.