Chemical Injury — Emergency Management

First Aid Before Presentation

If a patient splashes a chemical in their eye at home or at work, the single most important instruction is to irrigate immediately with whatever clean water is available, before doing anything else — before calling a clinic, before trying to identify the exact product, and certainly before attempting to patch the eye or apply any ointment. The final visual outcome in a chemical injury depends heavily on how quickly the offending agent is washed out, so irrigation should start immediately at the scene and continue en route to care, not be deferred until arrival at a clinic or emergency department.

Emergency Irrigation Protocol

Chemical injury is the one eye problem that is treated before checking vision. The most appropriate immediate first step in management, ahead of any other evaluation, is copious irrigation of the ocular surface with saline or water — not cycloplegic drops, not a topical antibiotic, and not a pressure patch. Delaying irrigation for any other intervention worsens outcomes, and this is especially true for alkali burns, whose ongoing saponification means every additional minute of contact allows further penetration.

The Morgan Lens

In the emergency department, sustained hands-free irrigation is typically delivered with a Morgan lens — a simple device used to perform continuous irrigation of the ocular surface via a corneal-scleral contact shield connected to a suspended saline bag, rather than having a clinician hold an irrigation stream by hand for the full duration. This lets high-volume irrigation continue for the many minutes it needs to run while freeing staff to work on other parts of the evaluation and to prepare pH testing supplies.

Irrigation Duration and pH Endpoint

Patients with chemical injuries should be instructed to irrigate for at least 20 minutes continuously — immediate and prolonged irrigation limits chemical exposure, and first responders recommend a minimum of 20 minutes of continuous irrigation as a starting point, not a fixed ceiling.

Duration by the clock, however, is not the actual stopping criterion. Irrigation should be guided by pH, not by fixed volume or time, and should continue until litmus paper testing of the ocular surface confirms the tear film pH has normalized. The target endpoint is a pH of 7.4 — the normal physiologic pH of human tears, close to that of plasma. Once pH first reads as normalized, irrigation should be stopped briefly and the pH rechecked after roughly 5 minutes (some sources describe a slightly longer 20–30 minute recheck window) to ensure the reading is stable and the eye hasn't drifted back toward an abnormal pH as chemical trapped in tissue or fornix debris continues to leach out.

Fornix Examination and Debris Removal

Once irrigation is well underway, the examiner must evert the eyelids — including double eversion of the upper lid — to expose the superior and inferior conjunctival fornices. This step exists to find and physically remove retained particulate matter, such as fragments of cement or lime, that can lodge in the fornices and continue releasing chemical directly onto the ocular surface for as long as they remain in place, effectively defeating the purpose of irrigation if missed.

Cycloplegia for Pain Control

In the acute phase of a chemical injury, cycloplegic drops are used primarily to paralyze the ciliary muscle and reduce pain. Cycloplegia helps prevent the pain of iris and ciliary spasm that accompanies the traumatic iritis a significant chemical burn typically provokes, and is a standard adjunct once irrigation and the fornix exam are complete.

Hydrofluoric Acid: Calcium Chelation

Hydrofluoric acid exposure adds a step beyond standard irrigation because of its fluoride ion's ability to chelate calcium (see the Pathophysiology page in this series for the underlying mechanism). Because significant exposure can cause systemic hypocalcemia in addition to local ocular damage, calcium gluconate is used as a chelating countermeasure in significant hydrofluoric acid exposures — irrigation still comes first, but hydrofluoric acid is the one chemical agent in this cluster where the emergency response extends beyond the eye itself toward systemic monitoring and correction.

A Related Historical Example: Neonatal Prophylaxis

A useful related example of a chemical agent itself causing ocular injury, rather than treating one, is neonatal ocular prophylaxis. Silver nitrate was historically used to prevent neonatal conjunctivitis but was largely replaced by erythromycin ointment because silver nitrate causes chemical conjunctivitis — it is irritating to the neonatal eye and produces a temporary chemical conjunctivitis, whereas erythromycin has a more favorable side-effect profile while still providing effective prophylaxis. It's a helpful reminder that "chemical injury" isn't limited to industrial accidents — even a deliberately administered prophylactic agent can produce a mild version of the same kind of surface irritation.

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