Ocular chemical injury is a medical emergency where the duration of exposure directly correlates with the severity of the damage and the final visual outcome. This type of burn occurs when an acidic, alkaline, or other irritant substance contacts the delicate surface of the eye. Time is the single most important factor in determining whether sight can be preserved, meaning immediate action is necessary to halt the chemical reaction.
Immediate Emergency Response: The Flushing Protocol
The foremost priority following a chemical splash is to dilute the substance by initiating a continuous, high-volume wash, often called the flushing protocol. This immediate irrigation is the only action proven to reduce the severity of the burn before professional medical help is available. Any source of clean water can be used, including a sink faucet, a water bottle, or a shower, with lukewarm tap water being perfectly acceptable.
The affected eye must be held open with the fingers, fighting the natural reflex of the eyelid to clamp shut due to pain, known as blepharospasm. The stream of water should be directed gently onto the eye, aiming to wash the chemical away from the other eye, ideally from the side near the nose outward toward the ear. If both eyes are affected, it is often easiest to get into a shower and aim the water stream at the bridge of the nose.
This decontamination process must be sustained for a minimum of 15 to 20 minutes, or until emergency medical services arrive. During the flushing, the eye should be moved in all directions to ensure the water reaches all surfaces, particularly underneath the eyelids where chemical residue can become trapped. Any contact lenses should be removed after the initial few minutes of rinsing, as the flushing action can often dislodge them naturally.
Seeking Professional Medical Care
The emergency flushing protocol is a first-aid measure only and does not replace the need for professional medical intervention. As soon as the initial irrigation is underway, someone must call emergency services or arrange immediate transport to the nearest emergency department. The eye should continue to be flushed during transport if a portable water source, such as a bottle, can be safely used.
Upon arrival at the medical facility, the attending staff must be provided with specific information to guide their treatment plan. It is necessary to identify the exact chemical agent involved, which can often be accomplished by bringing the chemical container or a photograph of the label. The medical team will also need to know the approximate duration of the exposure and how long the eye was flushed before arrival.
The medical assessment will include checking the ocular surface pH to confirm that the irrigation has returned the eye to a neutral range, typically between 7.0 and 7.2. This pH reading is a direct measure of the burn’s severity and the effectiveness of the initial flushing. Further treatment will focus on pain relief, removing any remaining particulate matter, and beginning medications to prevent infection and control inflammation.
Understanding Chemical Agents (Acids vs. Alkalis)
Chemical burns are classified by the nature of the substance, with acidic and alkaline agents causing damage through distinct biological mechanisms. Acidic substances (pH below 7) typically cause coagulative necrosis upon contact with the ocular surface. This process involves the rapid denaturation and precipitation of tissue proteins, which creates a protective barrier of dead tissue that limits the acid’s penetration into deeper eye structures.
Alkaline, or basic, substances (pH above 7) are far more dangerous to the eye and are responsible for the most severe injuries. Alkalis cause liquefaction necrosis, a destructive process where the chemical rapidly penetrates the corneal and conjunctival tissue. This penetration is facilitated by the saponification of the fatty acids in the cell membranes, allowing the chemical to move deep into the anterior chamber and cause widespread cellular death.
Because alkaline agents continue to destroy tissue long after initial contact, they can reach and damage the iris, lens, and ciliary body. Common alkaline agents include sodium hydroxide found in drain cleaners and lime from cement. Their ability to rapidly penetrate the eye necessitates urgent and prolonged irrigation, regardless of whether the agent is known to be acid or alkali.
Long-Term Recovery and Prognosis
The long-term outlook following a chemical burn depends on the initial severity of the injury, particularly the damage to the cornea and the limbal stem cells. These stem cells, located at the border of the cornea and the conjunctiva, are responsible for continuously regenerating the corneal surface epithelium. Damage to this area can lead to a condition known as limbal stem cell deficiency.
Loss of these cells results in the conjunctiva growing over the cornea, causing opacification, neovascularization, and significant vision impairment. Other potential long-term complications include cataracts, chronic inflammation, and glaucoma due to damage to the eye’s internal drainage system. Severe injuries often require multiple interventions over time to restore the ocular surface.
Subsequent treatments may involve surgical procedures such as amniotic membrane transplantation to promote healing and reduce inflammation. For eyes with extensive damage, vision may be restored through limbal stem cell grafting, where healthy stem cells are transplanted onto the damaged surface. In the most challenging cases, a keratoprosthesis (an artificial cornea) may be required to achieve functional vision.