Eye trauma

The type and extent of damage depends on the mechanism and force of injury. According to the US Eye Injury Registry database, 43% of ocular injuries occur in the home, 20% at work, 15% on the street or highway, and 13% due to sports and recreational activities.[1]

Blunt objects are the main cause of serious ophthalmic injury (34%), followed by sharp agents (26%) and motor vehicle crashes (10%).[1] Chemical splashes with alkalis or acids (e.g., ammonia or bleach) are among the most urgent of ophthalmic emergencies.

Falls are an important cause of eye trauma (approximately 33.8 encounters per 100,000 population), especially in women, followed by older people and children.[9] Corneal abrasions and external foreign bodies are common diagnoses in US emergency departments.[12] Corneal abrasions can be caused by fingernails, animal claws, paper or cardboard edges, makeup applicators, hand tools, or foreign bodies lodged under the eyelid.

Increased seatbelt use has reduced the number of eye injuries by up to 65%, while airbags have reduced the risk of ocular trauma from car collisions by 60%.[8][13][14] Airbags can, however, cause corneal abrasion, eyelid laceration, and hyphema.[15] Sports and recreational injuries are important causes of ocular trauma worldwide. Small, fast projectiles (e.g., paintball or BB gun pellet) can cause devastating eye injuries.

Fireworks can be a significant source of eye injury.[1][16] Severe ocular trauma occurs occurs in 18.2% of firework injuries, resulting in severe vision loss in 16% and enucleation in 3.9%.[17] Countries with restrictive firework laws have shown an 87% lower incidence of trauma.[17]

Blunt injuries

A direct blow to the eye causes a blunt or contusional injury. This can range from a simple "black eye" to severe intraocular disruption, including globe rupture.[18] The severity of eye injury depends on the size, hardness, and speed of the blunt object, as well as the force applied directly on the eye. A wound site from prior surgery represents a major risk for rupture.[19][20]

Blunt trauma may result in injuries to the bone around the eye (blow-out orbital fracture) and lid contusions. Ocular injuries include subconjunctival hemorrhage, hyphema (blood in the anterior chamber of the eye), iris or lens injuries, vitreous hemorrhage, retinal tears or detachment, choroidal rupture, or a ruptured globe.

Hyphema is a hallmark of severe intraocular blunt trauma. It is five times more common in males than females; peak incidence is at ages 10-20 years.[21][22] Elevated intraocular pressure occurs in nearly 40% of patients with hyphema.[23] Rebleeding may occur in the first 5 days. Associated ocular injuries can include traumatic mydriasis, angle recession, traumatic recurrence, disruption of the angle structures, cataract, and posterior-segment injuries.

Open globe injuries

An open globe injury is defined by the presence of a full-thickness defect in the eyewall (cornea or sclera).
Open globe injuries can be further classified as ruptures, lacerations, or intraocular foreign bodies. Ruptures are caused by blunt injuries and tend to occur at the site of greatest structural weakness (i.e., the limbus, behind the insertion of rectus muscles, the optic nerve head, or prior surgical wound sites). Lacerations are typically caused by a sharp object and can be described as penetrating (entry wound but no exit) or perforating (entry and exit wound). Intraocular foreign bodies are a specialized type of laceration defined by the presence of a retained object in the eye.
Signs of an open globe injury include 360 degrees of hemorrhagic chemosis, a peaked pupil due to the iris at the wound, a shallow anterior chamber, and a lower intraocular pressure. Note that a normal or high intraocular pressure should not exclude the possibility of an open globe injury.
The prognosis of an intraocular foreign body injury depends on the location and speed of the injury, as well as the size and composition of the foreign body. Inert, nontoxic, sterile materials, such as plastic and glass, are better tolerated within the eye. Metals such as copper and iron are poorly tolerated, causing chalcosis and siderosis, respectively. Injuries with organic matter are at high risk for contamination and may be associated with keratitis or endophthalmitis (bacterial or fungal).
Ocular injuries may affect the lens and lead to cataract formation at the time of injury or over weeks, months, or years. Foreign bodies that enter the posterior segment may be associated with vitreous hemorrhage, retinal tears, retinal detachments, or endophthalmitis. Perforating injuries are rare but can occur with high-velocity injuries (e.g., a gunshot wound).

Burns

Chemical splashes are true ocular emergencies and can cause extensive damage of the ocular surface. The duration of contact between eye and agent, together with the agent's characteristics are the primary factors in determining the outcome.[24]
Depending on the degree of penetration, different ocular structures may be affected, including the conjunctiva, the cornea, limbal stem cells, the ciliary body, and the lens.[25]

Alkalis penetrate the eye more readily than acids and can cause severe injuries. The hydroxyl ion of an alkali causes fatty acid saponification, which facilitates further penetration of the chemical agent.
Acid injuries tend to be less severe because acids cause protein denaturation and precipitation, keeping the offending agent confined to the ocular surface and limiting the damage.

Ultraviolet radiation burns (e.g., from unprotected welding, tanning booth exposure, or excessive sunlight exposure) may injure the eyes. Ionizing radiation is associated with cataract formation.

Definitions of ocular trauma terms[1]

Eyewall injury: injury to the cornea or sclera.
Closed globe injury: eyewall does not have a full-thickness wound.
Open globe injury: full-thickness wound of the eyewall.
Rupture: full-thickness wound of the eyewall caused by a blunt object.
Laceration: full-thickness wound of the eyewall, usually caused by a sharp object.
Penetrating injury: single laceration of the eyewall (entrance), usually caused by a sharp object.
Intraocular foreign body injury: retained foreign object, type of penetrating injury.
Perforating injury: entrance and exit wound of the eyewall, usually caused by a sharp object or missile.

The Birmingham Eye Trauma Terminology System[2][3]

Closed globe injuries:

Cornea and the sclera are not breached through and through.
Contusions result from blunt trauma without an open wound of the eyewall.
Lamellar lacerations are partial-thickness wounds of the cornea or sclera.

Open globe injuries:

Defined by full-thickness wound of the eyewall.
Ruptured globes are caused by blunt trauma.
Lacerations are produced by sharp objects.
Penetrating injuries are characterized by the presence of an entrance wound.
Perforating injuries are characterized by the presence of both an entrance and an exit wound.
Intraocular foreign bodies are technically penetrating injuries, but they are grouped separately because they have different clinical implications.

Pathophysiology

Classification

Definitions of ocular trauma terms[1]

The Birmingham Eye Trauma Terminology System[2][3]