penetration Alkaline substances tend to cause more damage as they cause saponification of fatty acids and can essentially “melt” the cornea and gain access to the internal structures of the eye Goals of Treatment Chemical injury to the eyeball is a true ocular emergency requiring immediate assessment and intervention by ED personnel Copious irrigation, even prior to ocular examination in many cases, is necessary to minimize damage to the ocular surface and is the mainstay of treatment if exposure is suspected Emergency management may be the most important factor in determining long-term visual outcome Clinical Considerations Clinical Recognition Often, there is a clear history of a noxious substance coming in contact with the ocular surface It may also be that the event is not witnessed and a parent may not be certain of the caustic exposure Thus, the ED clinician must maintain a high index of suspicion in children presenting with photophobia or an irritated, red or painful eye of acute onset A prompt pH test done by touching a litmus strip to the eye can be useful in detecting acidic or alkaline conditions It is also important to determine whether particulate matter may have been deposited on the ocular surface Smoke can cause chemical conjunctivitis, particularly in housefires when chemicals are liberated into the air from burning plastics and other substances Foreign bodies such as ashes and other particulate matter in smoke are not uncommon The examiner must also assess the degree of exposure If a child has no symptoms (e.g., pain, photophobia) or signs (e.g., red eye, epiphora, conjunctival swelling) and a weak history of actual chemical exposure to the eye it may be acceptable to avoid lavage Clinical Assessment A thorough clinical examination of the eye is often deferred until after irrigation if there is confirmation, or strong suspicion of, chemical exposure Immediate intervention is essential to improving the patient’s prognosis Management Any patient with sufficient history should be immediately placed in the supine position so ocular lavage may be started This procedure can often be frightening and anxiety provoking for a child, and some level of restraint is often needed Sedation and topical anesthetic may be helpful, but the physician should not delay lavage while waiting for either of these adjunctive therapies Usually, the irrigating solution itself will induce cold anesthesia If active manual irrigation is performed, the eyelids must be retracted for maximal exposure of the cornea and conjunctiva A speculum or Desmarres retractor may be used to help obtain optimal exposure A typical eye irrigation setup includes an IV pole and a L normal saline IV bag attached to a tubing set without a needle on the end While the provider holds the distal end of the tubing over the patient’s eye the irrigation solution is allowed to flow, with the system at its maximum flow rate, across the surface of the open eye from medial to lateral If both eyes have been exposed, a set of nasal cannula prongs can be attached to the IV tubing and then the prongs can be taped over the patient’s nasal bridge (each prong directed at the medial aspect one eye) Both eyes can then be easily lavaged simultaneously The Morgan Lens is a commercially available sterile plastic device that resembles a contact lens It fits over the eye and can be connected to tubing that allows for continuous flow of fluid on to the ocular surface ( Fig 123.12 ) It is quick and easy to set up and provides a “hands-free” method of irrigating the cornea and conjunctiva A mechanism to collect excess fluid (such as towels, suction, basins, etc.) should be in place Virtually any IV fluid can be used for ocular lavage, although normal saline solution is most commonly used The use of more pH neutral solutions (Ringer’s lactate, NS with bicarbonate buffer, or a balanced salt solution) may decrease ocular discomfort and irritation associated with irrigation Regardless of the method used, lavage should be continued until the involved eye(s) has received either L of fluid or until approximately 20 minutes have elapsed Lid eversion should be performed (see Chapter 114 Ocular Trauma , Fig 114.2 ), and lavage should be continued with the lid in this position so that the conjunctiva under the upper lid may also be cleansed Mechanical debridement should be limited to the removal of visible particles from the ocular surface, which may contain small amounts of the offending agent or necrotic debris After irrigation is performed as described above, the pH should be remeasured every 15 to 30 minutes to determine whether it has normalized (pH 6.5 to 7.5) and is equal between the two eyes The end point of equality should only be used if one eye has not been exposed to caustic chemicals The conjunctiva under the upper lid may also be tested separately because noxious material can be harbored in the recess above the eye under the lid Irrigation should continue until normalization of pH has been achieved FIGURE 123.12 Irrigation setup for ocular lavage (A ) and the Morgan Lens (B ) Ophthalmology consultation is indicated in cases of significant chemical injury Waiting for the consultant should not delay irrigation and the ophthalmologist should be notified while lavage is ongoing In cases of very minor exposure to substances that are clearly neither alkaline nor strongly acidic, and when the eye is not injected, an ophthalmology consultation may be deferred However, the ED clinician should be cautious about the absence of conjunctival injection because alkali burns can cause blanching of the conjunctiva, which is a poor prognostic sign Hordeolums and Chalazions A hordeolum is an acute infection of the eyelid that presents as a localized painful swelling Hordeola can be external (resulting from blockage of a gland of Zeis on the lid margin; classic “stye”) or internal (resulting from blockage of a meibomian gland) A chalazion, which also results from a blocked eyelid gland, may initially present with some inflammation and tenderness, but typically progresses to a painless localized eyelid swelling as the inflammation resolves Styes and chalazions are typically sterile but can progress to infection, most commonly with staphylococcal species FIGURE 123.13 Acute stye (external hordeolum) Both conditions may present acutely with localized lid swelling, erythema, and tenderness Styes are associated with swelling and purulent drainage at or near the lid margin ( Fig 123.13 ) More than one lesion may occur simultaneously, and more than one lid may be involved An acute chalazion causes swelling and redness in the body of the eyelid and may be associated with drainage on the conjunctival surface of the eyelid with or without a red eye It may also drain via the skin ( Fig 123.14 ) A chalazion typically enters a chronic granulomatous phase in which there is a nontender, noninflamed, mobile pea-sized nodule within the body of the eyelid ( Fig 123.15 ) History can be helpful in establishing these diagnoses because patients often have had recurrent lesions in the same or other eyelid