Chapter 155. Ocular Burn Management and Eye Irrigation

Ocular burns are true emergencies and represent a significant minority (7.2% to 9.9%) of ocular trauma cases.1,2 Chemical burns account for the large majority of ocular burns, with thermal burns being the second most common cause.3 Most victims are young males.2,4 The industrial workplace is the most common setting, although a significant number of cases occur in the home.4 Assaults are a significant cause of ocular burns in the lower socioeconomic groups of large cities.4,5

Caustic agents are primarily responsible for the most severe chemical ocular burns. Most reports indicate that alkali burns are more frequent than acid burns.1,3,4 Examples of more common alkalis and acids are listed in Table 155-1.4,6–13 Ammonia causes the most serious alkali burns, while calcium hydroxide (lime) is the most common cause of alkali burns.4 Hydrofluoric acid causes the most serious acid burns, while sulfuric acid is the most common cause of acid burns.4 Fortunately, caustic agents account for only a minority of chemical ocular exposures.1 Most chemical ocular exposures are due to relatively innocuous noncaustic substances (e.g., shampoos, hair sprays, and personal defense sprays) and therefore do not cause significant or lasting damage.1,14,15

Ocular irrigation is a simple procedure that is commonly employed in the Emergency Department. It is potentially an eye-saving procedure in the setting of significant chemical ocular burns. Physicians, nurses, and emergency medical personnel who deal with ocular emergencies should be trained in ocular irrigation. When possible, first aid personnel in the workplace should be familiar with the use of ocular irrigation.16 Most importantly, ocular irrigation must be employed rapidly.1,17 Delays in irrigation can limit its effectiveness and increase morbidity.3

The anterior surface of the globe is the major target of toxins in ocular burns (Figure 155-1). The eyelids are the most important protective structure for the eye. The orbicularis oculi muscle is innervated by branches of the facial nerve and closes the eyelids in response to noxious stimuli. The cornea provides little in the way of protection from chemical agents. The cornea is composed of five convex and transparent tissue layers. The cornea's major function is the refraction and transmittance of light. Despite its avascularity, the cornea is exquisitely sensitive to pain. Paradoxically, more extensive burns may be less painful due to destruction of corneal nerve endings and resultant anesthesia.18 The cornea merges with the sclera to form the limbus at its outer margins. Stem cells at the level of the limbus are responsible for regeneration of the corneal epithelium. The corneal epithelium is unable to regenerate when the limbus is damaged. Although tougher than the cornea, the fibrous sclera is also susceptible to chemical injury.

The sclera is covered by the bulbar conjunctiva, which becomes the palpebral conjunctiva as it reflects onto the inner surface of the eyelids. These areas of reflection are referred to as the superior and inferior fornices of the upper and lower eyelids, respectively. The spaces between the eyelids and the globe are referred to as the superior and inferior conjunctival sacs (also known as palpebral sulci). Posterior to the cornea lies the anterior chamber, which contains the aqueous humor. The anterior and posterior chambers are separated by the iris, ciliary body, trabecular meshwork, and lens.19

The damage produced to the eye by toxins depends on several factors: duration of contact; anion or cation concentration; and amount, pH, and inherent toxicity of the chemical.17,20 Alkalis generally produce the most damage. Alkalis release hydroxyl ions that combine with tissue fatty acids and proteins, causing liquefaction necrosis.11 The resultant degradation of corneal tissue allows for easy passage of the chemical into the anterior chamber. This causes a rapid rise (within a few seconds to a few minutes of contact) in aqueous humor pH and consequent damage to the iris, lens, ciliary body, and other ocular structures.4,18,21 Damage to these structures and the cornea results in decreased visual acuity, secondary glaucoma, and cataracts. This damage can continue as the anterior chamber pH may remain elevated for hours. Measurement of tear film pH immediately after irrigation will often yield a normal pH.7,8 This may be falsely reassuring. It may either reflect the pH of the irrigant or a transient neutralization of the tear film pH.18 Alkalis may diffuse from the anterior chamber to the anterior ocular surface several minutes after irrigation has been discontinued, causing the tear film pH to rise again.

In general, acids cause less damage than alkalis. Acids lead to coagulation necrosis and protein precipitation, which usually prevents penetration beyond the cornea.11 Exceptions include acids in higher concentration (particularly sulfuric acid) and hydrofluoric acid, which behaves more like an alkali.4,5,18 These acids, like alkalis, can cause damage to deeper structures. Ocular burns caused by weaker acids can progress if treatment is delayed.18

Most noncaustic chemical eye exposures involve nontoxic agents that do not penetrate the cornea and cause only mild and self-limited irritation. Notable exceptions include surfactants and high-concentration lacrimators, both of which can cause damage to deeper structures.10,18 Lacrimators in low concentration (e.g., tear gas) stimulate corneal nerve endings, causing pain and tearing, but they do not cause deeper injury.18 Surfactants can cause significant damage that is often minimally symptomatic.10 Although most solvents can cause sizable superficial corneal defects, reepithelialization is the rule and deeper tissues are spared.10,18 Corneal injuries with capsicum (i.e., pepper spray) usually cause self-limited injuries, but significant corneal defects requiring Ophthalmology follow-up do occur occasionally.22

The treatment of chemical exposures to the eye is the primary indication for ocular irrigation. In this setting, irrigation has three principal objectives: immediate dilution of the offending agent, removal of the agent, and normalization of anterior chamber pH.18 Nonembedded foreign bodies that are too small or too numerous to be removed adequately with a forceps or a cotton-tipped applicator can usually be removed with irrigation. Foreign bodies that are suspected but cannot be visualized may be removed with irrigation. Certain ocular infections are treated with antibiotics delivered by eye irrigation, although this is not a usual indication in the Emergency Department.

There are no true contraindications to ocular irrigation. An irrigating lens (e.g., Morgan Lens) should not be used if a deep corneal injury or a foreign body is suspected.23 This lens may cause the foreign body to further injure the cornea or penetrate the globe. It is preferable to carefully employ the traditional method of irrigation using intravenous tubing and eyelid retraction rather than commercial devices that contact the globe in the setting of an actual or potential globe penetration or rupture.

• Topical ophthalmic anesthetic agent, 0.5% proparacaine or 0.5% tetracaine
• Towels and a basin to collect fluid runoff
• Bags of crystalloid solution
• Intravenous tubing
• Gauze pads
• Cotton-tipped applicators
• Lid retractors, paper clip or Desmarres
• Commercial irrigation device, Morgan Lens or Eye Irrigator
• Protective eyewear, gloves, and gowns for healthcare personnel

Patients with ocular chemical burns may also have upper respiratory tract injuries, gastrointestinal tract injuries, and facial burns.1 Nonchemical traumatic injuries are also possible. Airway, breathing, and circulatory problems should take priority. Significant ocular burns will need to be dealt with early and simultaneously with other problems. Initially, irrigation of the periocular skin should be performed with ocular irrigation itself such that residual toxin does not enter the eye causing further chemical injury.

Patients with isolated ocular injuries often have severe pain that requires parenteral narcotics. If this is the case, a monitored setting is appropriate. Intravenous sedatives and analgesics may facilitate ocular irrigation in a patient with severe pain and blepharospasm. Place the patient supine. Place towels and a basin under the patient's head to collect the runoff irrigant solution. Due to the speed with which ocular irrigation must be started, an explanation of the risks and benefits of the irrigation procedure should be offered to the patient while preparing for and initiating irrigation. Healthcare personnel and first-aid workers in the workplace are at risk for injury themselves. Protective equipment is essential and should be easily and rapidly accessible. Contaminated clothes should be removed and bagged in plastic until they can be cleaned or discarded.15

A topical ophthalmic anesthetic agent, if immediately available, should first be instilled into the inferior conjunctival sac. Commonly available topical anesthetics include tetracaine and proparacaine. Proparacaine causes less irritation than tetracaine.24 Each has a duration of action of approximately 10 minutes. Frequent readministration of the topical anesthetic may be necessary every 5 to 10 minutes to ease patient discomfort and facilitate irrigation. An alternative to readministration of local anesthetic would be to add 10 cc of 1% lidocaine to 1 L of crystalloid solution. Compared to an initial instillation of two drops of tetracaine alone, O'Malley et al found that lidocaine added to the irrigant in this way decreased the discomfort of irrigation when the irrigation lasted more than 10 minutes.25

Ocular Irrigation

Hang the bag of crystalloid solution at a height of 70 to 200 cm above the patient's head in order to obtain an adequate flow rate.26,27 The traditional eye irrigation technique involves directing the flow of crystalloid solution over the globe at a wide open rate (Figure 155-2). Hold the end of the intravenous tubing 3 to 5 cm above the patient's eye to avoid blunt injury to the ocular surface. An assistant is usually needed to hold the eyelids open. Dry gauze pads will facilitate one's ability to maintain a grip on the slippery eyelids and keep them open. Direct the flow of crystalloid solution at the entire surface of the globe, including into the conjunctival sacs and down to the conjunctival fornices.18,28 Having the patient look in a direction opposite to where the irrigant is directed helps in this regard.29 Although one can point the stream directly at the conjunctiva, it is better to direct it across the cornea in order to reduce the potential for further corneal injury.23

Manual retraction of the eyelids with gauze pads does not always allow for adequate irrigation of the conjunctival fornices. In these instances, eyelid retractors (Desmarres or bent paper clip) must be employed (Figure 155-3). The eye must be well anesthetized when using eyelid retractors, and care must be taken to avoid further ocular injury. Desmarres retractors are preferred to paper clips. Many paper clips are coated with nickel or silver that, when the paper clip is bent, can flake off, resulting in iatrogenic foreign bodies.30 The use of a Water-Pik or handheld drench hose has been described but offers no definite advantages over intravenous tubing.31,32

Two commercially available devices exist which are less labor-intensive and facilitate ocular irrigation. The Morgan Lens (MorTan Inc., Missoula, MT) is a scleral contact lens-type device that is designed to fit over the anterior ocular surface (Figure 155-4A). Connect the proximal end of the device to intravenous tubing and start a minimal flow of irrigant solution through the Morgan Lens. Retract the upper eyelid and ask the patient to look down. Insert the lens under the upper eyelid (Figure 155-4B). Retract the lower eyelid and ask the patient to look upward. Insert the lower part of the lens under the lower eyelid (Figure 155-4C). Increase the flow of the irrigant solution through the lens. Remove the lens by reversing these steps (Figure 155-4D).

The Eye Irrigator (American Health & Safety, Madison, WI) delivers the irrigant via a U-shaped cannula with multiple perforations through which the irrigant flows (Figure 155-5A). Insert a speculum into the inferior conjunctival sac and retract the lower eyelid (Figure 155-5B). Insert the Eye Irrigator under the upper eyelid (Figure 155-5B). These steps are reversed for removal of the device. This device is somewhat similar to irrigating systems reported both by Yamabayashi and Terzidou.26,27

The EyeCap (Splash Medical Devices LLC, Atlanta, GA) is a simple device to irrigate an eye (Figure 155-6). The unit is quick to set up by just screwing it onto a bottle of sterile saline. The base of the unit has universal threads to attach to a bottle of sterile saline (Figure 155-6). The other end is wide and contoured to fit over the orbit. The device allows the saline to deflect off its sidewalls and pool over the eye. The patient can open their eye “under water” to gently allow high volume eye irrigation. This device cannot be used for foreign bodies embedded in the cornea, penetrating injuries, or if a ruptured globe is suspected.

Solid Particles

Ocular burns can be caused by chemicals that are primarily in the solid form (e.g., lime). Prior to irrigation, attempt to remove as much solid as possible using a moistened cotton-tipped applicator while everting and retracting the eyelids. Quickly proceed to irrigation once most of the solid material has been removed or if removal is limited by blepharospasm. Copious irrigation is often successful in removing any residual solid material.17 Proceed directly to irrigation when solid material is not suspected in significant quantity and inspect the conjunctival sac for foreign material once the initial irrigation has been completed.

Contact Lenses

Concern that contact lenses may trap chemicals between them and the cornea appears to be unfounded. Contact lenses may, in fact, be protective and act as a shield between the chemical and the cornea.33,34 Irrigation should not be delayed in order to remove a contact lens unless it appears that a contact lens can be removed easily and quickly. This is the case even when commercial irrigation devices are used. Contact lenses can be removed once an initial period of irrigation has been completed. Refer to Chapter 154 regarding the details of contact lens removal. The contact lenses should be discarded as the chemical may be absorbed by the contact lens, only to be released onto the surface of the cornea if reused.15,33

Irrigation Fluid

The choice of irrigation fluid is much less important than the speed with which irrigation is started.18,21 Tap water is perfectly acceptable at the scene of the chemical exposure, although there may be problems with patient discomfort.17 Normal saline and Ringer's lactate solution are both acceptable during ambulance transport and in hospital. It has been thought that the more neutral pH of Ringer's lactate solution (pH 6.0 to 7.2) should cause less patient discomfort than normal saline (pH 4.5 to 6.0). Similarly, balanced salt solutions (e.g., BSS Plus, Alcon Laboratories, Fort Worth, TX) should theoretically cause less patient discomfort due to its enhanced buffering capacity, physiologic osmolarity, and physiologic pH. These theories have yet to be clearly substantiated.14,35,36 Use the irrigant fluid that is most readily available. Balanced salt solutions should be used only in patients who require prolonged irrigation and for whom other irrigants are unsuitable due to their expense and time-consuming preparation (requiring reconstitution in glass bottles).14,35

The use of warmed irrigation fluid appears to increase patient comfort.37 Ernst et al have reported an optimal irrigant temperature of 32.2 to 37.8 °C (90 to 100 °F). Werwath et al found that 120 seconds were required to heat 1 L bags of normal saline and Ringer's lactate solution to a temperature of 101 °F in a microwave oven set at the highest cooking intensity.38 This cannot be routinely recommended, as microwave ovens vary and overheated irrigant fluid will cause secondary injury. Irrigation should not be delayed while an irrigant fluid is being warmed despite the potential value of warmed fluid. Commence irrigation with room temperature crystalloid solution and switch to a warmed crystalloid solution once prepared. Although not experimentally validated, Rost et al has suggested that cooler liquids at the beginning of irrigation may help reduce the heat of the reaction, thus limiting chemical injury.21 Saidinejad and Burns has put forward the unproven theory that using a cold irrigant may provide cold anesthesia.39

There is probably no chemical ocular burn for which crystalloid irrigants are contraindicated.18 Metallic sodium, metallic potassium, and white phosphorus may react violently. Remove any visible solid particles with a cotton-tipped applicator prior to irrigation. Irrigation with copious amounts of crystalloid probably dissipates the heat of the initial reaction more than it initiates a thermochemical reaction.18

Specific Antidotes

The mainstay of treatment for chemical ocular burns is early and copious irrigation. Although specific antidotes usually play little role in the treatment of most ocular exposures, there are some instances where antidotes can be helpful once the initial irrigation has been performed. Consultation with a poison center or Toxicologist should be considered in cases of exposure to unusual agents.23

EDTA may be helpful in removing adherent calcium hydroxide corneal deposits from lime exposures that cannot be removed with a cotton-tipped applicator or toothless forceps.1,10,23 A 0.05 M neutral solution of EDTA can be prepared by diluting 20 mL of Endrate disodium (150 mg/mL) with 180 mL of normal saline.10 A cotton-tipped applicator soaked in the EDTA solution can be used to loosen such deposits. EDTA may also be useful in exposures to potassium permanganate and zinc chloride.10

Ascorbic acid may be useful in potassium permanganate exposures. A 5% solution can be prepared by dissolving a 500 mg tablet of ascorbic acid in 25 mL of normal saline. The resultant manganese oxide deposits can be dissolved by dripping the solution into the eyes from a moistened piece of gauze.40

Numerous other miscellaneous antidotes can be used for specific exposures. Copper sulfate (3% solution) can be used to negate the effects of embedded white phosphorus.10,23 Polyethylene glycol may be useful in phenol exposures.41 Mineral oil has been suggested in the removal of cyanoacrylates.23 Calcium gluconate solutions have no beneficial effect in ocular exposures to hydrofluoric acid.42

Duration of Irrigation

Irrigation should be continued for 20 minutes in the home or workplace prior to patient transport. Emergency medical technicians should continue irrigation during ambulance transport until hospital arrival. The duration of any further irrigation in the Emergency Department depends on the severity of the exposure and the nature of the agent.

Minor exposures with nontoxic substances need not undergo copious irrigation. Irrigation with crystalloid solution using a squeeze-type bottle may be sufficient. In fact, irrigation that had been performed either in the home or in the workplace may be all that is needed. However, treatment should proceed as for caustic agents if the chemical nature of the substance is unknown. Assume that any previous irrigation was inadequate and that further irrigation is necessary in the Emergency Department.4

Although no definite standard duration for ocular irrigation is available in the literature, most would agree that patients who are significantly symptomatic or who have received a caustic exposure should have their eyes irrigated with a minimum of 1 to 2 L of crystalloid solution over 20 to 30 minutes.17,43 Exposures to noncaustic agents, milder acid burns, and very mild alkali burns will usually not need further irrigation. Moderate to severe acid burns and anything more than a mild alkali burn will likely require more prolonged irrigation.

The duration of irrigation for caustic exposures is in part governed by pH measurement. After the initial irrigation, measure the pH of the inferior conjunctival sac using wide-range pH paper (i.e., accurate in the pH range of at least 2 to 10) or litmus paper.10 Litmus paper with a narrower range and urine dipsticks may not be adequate. If the pH is abnormal, continue irrigation and recheck the pH at 10 to 15 minute intervals until it normalizes.10,23 If the pH has reached the near-normal range (i.e., 7 to 8), discontinue irrigation and recheck the pH in 10 to 30 minutes to ensure that it continues to remain normal.18,23 In clinically severe caustic burns, regardless of the ocular pH, irrigation should be continued until the patient is evaluated by an Ophthalmologist. Alkali burns are more likely to require prolonged irrigation than acid burns. In fact, several hours of irrigation may be required for severe alkali burns. In this instance, the Ophthalmologist may opt to perform a regional nerve block to incapacitate the orbicularis oculi muscle, thus limiting blepharospasm and improving patient comfort.11

Ocular assessment should be limited to observation of gross injury, assessment of ocular pH, and quick verification of visual acuity until irrigation is complete. These assessments should not be prolonged and should not delay initial irrigation. A full ophthalmologic assessment is required once irrigation has been discontinued. This should include a recheck of visual acuity, measurement of intraocular pressures, and a slit lamp examination to evaluate for corneal injury, uveitis, and globe perforation.

The extent of aftercare required is dependent upon the severity of the injury. Minor exposures to innocuous agents and very mild caustic exposures without corneal changes should be reevaluated in 24 hours if the patient is asymptomatic. Some exposures (e.g., gases, vapors, and fumes) can result in delayed evidence of corneal injury on slit lamp and fluorescein exams.10 Thus, patients with apparently minor exposures should be cautioned to return to the Emergency Department if their symptoms worsen or do not improve.

Patients with mild exposures that result in corneal defects should be treated with topical antibiotics that have antistaphylococcal and antipseudomonal activity.10 Ascertain the patient's tetanus immune status and administer prophylaxis as indicated. Analgesics or an eye patch may be offered if patient discomfort is significant.1,10 Cycloplegics should be prescribed in order to decrease the pain resulting from ciliary spasm and to decrease the risk of the formation of posterior synechiae if anterior chamber involvement is suspected.10,28 After a chemical burn, patients chronically using phosphate buffer-containing eye drops (e.g., timolol and latanoprost) are at greater risk of corneal calcification.44 Telephone consultation with an Ophthalmologist is recommended. Ophthalmology follow-up should occur within 24 hours.

Moderate to severe ocular burns require admission and acute evaluation by an Ophthalmologist. Medical treatment of secondary glaucoma may be required. Anterior chamber paracentesis and lavage may be needed early in the course of severe alkali burns in order to decrease the anterior chamber pH as well as intraocular pressure.1,10,23,41 Necrotic tissue will have to be debrided.4 The goals of longer-term therapy include the prevention of corneal ulceration, prevention of scarring of the anterior ocular structures, prevention of globe perforation, and the promotion of corneal reepithelialization.23 Steroids, nonsteroidal anti-inflammatory agents, frequent lubrication, and soft contact lenses may help in this regard.1,4 Ascorbic acid and collagenase inhibitors are experimental. More severe injuries require surgical intervention due to the loss of stem cells at the limbus and thus the loss of potential corneal reepithelialization.4

Pain and discomfort are common after ocular exposure to chemicals. These can be minimized with topical ophthalmic anesthetic agents, parenteral sedatives, and parenteral narcotics in the Emergency Department. Corneal injury is usually the result of the primary chemical injury. Corneal injury may result from the irrigant or irrigating device, particularly if improper technique is used. Frequent use of topical ophthalmic anesthetic agents can lead to corneal injury. Extrusion of ocular contents is possible in the setting of a globe penetration. The diving reflex is a rare but possibly significant complication. This reflex is mediated by the ophthalmic branch of the trigeminal nerve and the vagus nerve. It is triggered by a cold water stimulus to the face and results in bradycardia without hypotension. The diving reflex is more common in infants and children. Its clinical importance is greatest in patients with significant comorbid disease. Continuous cardiac monitoring is wise in these subsets of patients. Irrigation with warm water may limit this reflex.45,46

Ocular irrigation is an eye-saving procedure in the setting of significant ocular burns. For trained personnel, it is an easy and safe procedure to perform. First-aid workers, emergency medical technicians, and Emergency Department personnel should be trained in its use. Ocular irrigation should be performed rapidly with the most available nontoxic irrigant, as delays of even seconds can limit its effectiveness.