TRAUMATIC CORNEAL LACERATION AND PERFORATION

Signs and Symptoms

Traumatic corneal lacerations and perforations are invariably accompanied by a recent history of ocular injury. Typically, this involves a sharp object such as a knife, hand tool, tree branch or glass shard, although cases have been documented involving some very obscure items, including fish hooks, plastic toys, ninja stars and the talons from a bird of prey.1-4 Although fingernail scratches typically do not generate enough force to lacerate the cornea, this etiology has been documented in the literature; hence, it is important to rule out laceration in all cases of corneal trauma.5 Lacerations may also result from penetration by a high-velocity projectile or may occur secondary to severe blunt injury.6

Patients with corneal laceration typically report intense pain at the onset, although this may diminish over time due to severing of the corneal nerves. Additional symptoms may include photophobia, lacrimation and variably reduced vision. According to the database of the United States Eye Injury Registry (USEIR), corneal injuries are five times more likely in males than females, and are also more common in active, younger age groups.7

Typically, there will be pronounced ocular injection, secondary blepharospasm and pseudoptosis secondary to pain and photophobia. The corneal laceration may be obvious if it is large or irregularly shaped. One may observe a jagged defect that extends from the corneal epithelium into and through the underlying stroma. Small, linear breaks may be more difficult to visualize, because the opposing surfaces of the wound may close like a “flap-valve” under the sustained intraocular pressure of the eye. If the laceration is full thickness, the anterior chamber may be shallow or even flat, again depending upon the extent of the injury.

Aqueous can be visualized percolating from the edge of the wound when fluorescein is painted across the wound (Seidel’s sign). The intraocular pressure may be substantially reduced in cases of full-thickness lacerations and perforations, sometimes reaching as low as 0mm Hg to 2mm Hg, depending upon the timing of the evaluation compared to the time of injury.

One finding that is particularly diagnostic of a perforating corneal injury is the presence of air bubbles within the anterior chamber. Other key signs include corectopia and iris prolapse into or through the wound as internal ocular pressure forces tissue forward to plug the wound. Accompanying pathology related to the inciting trauma is also common; subconjunctival hemorrhage, hyphema, iridodialysis, lens dislocation, cataract, vitreous hemorrhage and rarely vitreous incarceration are all possible findings.4

While corneal lacerations typically encompass significant area, perforations do not and can easily be missed during the clinical exam. Corneal perforations typically involve a foreign object penetrating the cornea, such as a needle or tree twig, or a small projectile entering the cornea and lodging within the eye. Corneal perforations can partially or fully self-seal. As such, there may be no hypotony, the chamber may be shallow but formed, and there may be no Seidel sign.

Pathophysiology

The cornea possesses great tensile strength and is generally resistant to penetration by blunt perpendicular forces; however, tangential injuries of sufficient force—particularly those induced by sharp objects—have the potential to cause the lamellar sheets of the corneal stroma to separate, allowing for entry into the tissue.

A laceration refers to a wound produced by the tearing of a bodily tissue; it is usually traumatic, irregularly shaped and induced by a foreign object. Lacerations may vary in thickness. When the cornea is penetrated through all layers into the anterior chamber, it is referred to as a full-thickness laceration. A cleft that does not completely traverse the stroma and endothelium is considered a partial-thickness laceration.

The obvious danger in a full-thickness corneal laceration is the subsequent extrusion of intraocular contents through the wound or introduction of harmful matter or infectious microorganisms. Numerous cases of endophthalmitis have been documented, in some cases involving highly unusual organisms.8-10 As the pressure in the anterior chamber drops, the pressure from the vitreous body forces the lens and iris forward. That excessive manipulation or further trauma may induce a prolapse of these tissues through the laceration.

Management

From a primary care point of view, the management of corneal laceration involves basic first aid. The clinician must make a definitive diagnosis as quickly as possible using the least amount of manipulation or intervention.

To aid examination in cases of corneal trauma, it is often advantageous to instill a topical anesthetic. This helps to alleviate patient discomfort and permits the clinician to perform a more thorough evaluation of the eye, including visual acuity assessment, pupillary evaluation and biomicroscopy.

The downside of using a topical anesthetic—or any topical agent—in cases of corneal laceration is the potential for deep tissue toxicity or introduced infection. With a compromised cornea, topically applied drugs achieve intraocular concentrations much greater than normally intended. This can lead to unwanted sequelae. Hence, any topical agents should be used sparingly if at all, and preservative-free options, where available, are preferred.

To differentiate corneal abrasions and partial-thickness lacerations from full-thickness lacerations, perform the Seidel test. Fluorescein is applied directly to the wound, and then carefully inspected under cobalt blue illumination, either with a Burton lamp or at the biomicroscope. In cases of corneal perforation, aqueous will slowly percolate from the lesion, creating a dark-appearing area with a steady flow of fluid to the inferior fluorescent tear lake. As some small perforations can at least partially self-seal, the Seidel test may be negative.

If a high-speed impact has caused trauma, a negative Seidel test does not rule out corneal perforation. In these cases, a pressure Seidel test should be performed. The corneal defect is painted with fluorescein and mild pressure is applied to the globe through the sclera or eyelid while the patient is at the biomicroscope. If there is a self-sealing perforation, the additional light pressure will turn a negative Seidel test into a positive result. Otherwise, tonometry, gonioscopy and other procedures requiring pressure on the globe should be deferred if there is any known ocular perforation.

Once the diagnosis is established, the primary goal is to stabilize the eye and ensure that no further damage occurs. An eye shield should be gently placed to protect the globe; however, the use of a pressure patch or bandage contact lens is ill-advised in large corneal lacerations, primarily due to the manipulation required to apply these measures. In the event that material is lodged in the wound, it should not be removed as it may actually be plugging the wound. Immediately refer to a cornea specialist to initiate surgical repair of the laceration. Patients must be instructed not to eat or drink before the surgical consultation, because this may delay a surgical procedure. If the patient is nauseous or overly anxious, consider prescribing an antiemetic agent such as meclizine 25mg PO to prevent vomiting.

Repair of corneal lacerations involves a variety of efforts. Partial-thickness and self-sealing lacerations may be treated with nothing more than topical antibiotics, cycloplegics and a bandage contact lens, with close observation for any signs of ensuing endophthalmitis. Larger wounds or those that are prone to leakage may sometimes be managed with fibrin glue or cyanoacrylate tissue adhesive in lieu of surgical repair.11-15 Additionally, scleral patch grafts and amniotic membranes, often with adjunctive fibrin glue and cyanoacrylate adhesive, have been recently used with success.16-20 However, many corneal lacerations often require suturing to restore corneal integrity.

Clinical Pearls

With a corneal laceration, the patient may be tearing so heavily it renders the Seidel test inaccurate. In these cases, a shallow or flat anterior chamber, hypotony, or the presence of bubbles within the anterior chamber indicates a breach in the corneal integrity.

For full-thickness corneal lacerations, the less done in the office the better. Assess the injury, arrange for the appropriate referral and shield the eye gently for protection while the patient is in transit to the surgeon.

The patient should be educated that the entering acuity may represent the best vision that can be expected after surgical repair. Of course, acuity may improve following surgery; however, it is best not to elevate patient expectations.

A fresh, previously unopened bottle of topical anesthetic is preferred when a full-thickness corneal laceration or globe rupture is suspected to avoid ocular contamination.

Any eye injury from a high-speed projectile should be considered a perforation until proven otherwise. In some cases, ultrasound may be necessary to rule out intraocular foreign body.

Small corneal perforations may partially self-seal, giving a negative Seidel result.

Progressively worsening vision, pain, hypotony, shallow anterior chamber depth and hypopyon are indications of a corneal perforation and developing endophthalmitis.

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3. Jeng BH, Steinemann TL, Henry P, et al. Severe penetrating ocular injury from ninja stars in two children. Ophthalmic Surg Lasers 2001;32(4):336-7.

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13. Por YM, Tan YL, Mehta JS, Tan DT. Intracameral fibrin tissue sealant as an adjunct in tectonic lamellar keratoplasty for large corneal perforations. Cornea. 2009;28(4):451-5.

14. Khalifa YM, Bailony MR, Bloomer MM, et al. Management of nontraumatic corneal perforation with tectonic drape patch and cyanoacrylate glue. Cornea. 2010;29(10):1173-5.

15. Sharma A, Kaur R, Kumar S,et al. Fibrin glue versus N-butyl-2-cyanoacrylate in corneal perforations. Ophthalmology. 2003;110(2):291-8.

16. Sharma A, Mohan K, Sharma R, Nirankari VS. Scleral Patch Graft Augmented Cyanoacrylate Tissue Adhesive for Treatment of Moderate-Sized Noninfectious Corneal Perforations (3.5-4.5 mm). Cornea. 2013 Aug 22. [Epub ahead of print].

17. Samoila O, Totu L, Calugaru M. Methods for sealing of corneal perforations. Oftalmologia. 2012;56(2):34-9.

18. Grau AE, Durán JA. Treatment of a large corneal perforation with a multilayer of amniotic membrane and TachoSil. Cornea. 2012;31(1):98-100.

19. Chan E, Shah AN, O’Brart DP. “Swiss roll” amniotic membrane technique for the management of corneal perforations. Cornea. 2011;30(7):838-41.

20. Kim HK, Park HS. Fibrin glue-assisted augmented amniotic membrane transplantation for the treatment of large noninfectious corneal perforations. Cornea. 2009;28(2):170-6.