Chemical burn is a condition where powder or liquid chemical substances affect the eye or eyelid, causing injuries. Some of the burns are treated as true ocular emergencies requiring immediate and intensive evaluation and care.
Most chemical burns affect one eye. The most affected parts of the eye are often those found on the front surface, such as the cornea, conjunctiva, and sometimes the lens (inner structure). The burns that penetrate deeper than the cornea are severe and can lead to glaucoma and cataracts. Some burns result in severe pain causing the individual to shut the eyelids. This action keeps the chemical inside for more extended periods, further damaging the eye.
Chemical burns occur when chemical splashes over the face, rubbing eyes after handling chemicals, or powder blown into the face. Chemicals that enter the eye and into the bloodstream can cause poisoning compared to those that splash on the skin. Splashes from non-toxic substances are less serious and can be treated at home.
Chemical burns are classified according to their severity. They are:
- Grade I. This is a mild injury where the cornea remains very clear. Only the corneal epithelium is affected.
- Grade II. It is characterized by neovascularization and focal haze on the cornea.
- Grade III. There is ischemia in most of the limbus, extensive limbal stem cell loss, and profound corneal haze. Vision can be restored after appropriate treatment.
- Grade IV. The proximal conjunctival epithelium is destroyed, and the cornea is utterly opaque. There is also a total limbal stem cell loss. Vision recovery is possible, but very difficult.
- Acid burns
- Alkali burns
Causes & Risk Factors
Chemical burns typically affect young men aged between 20 and 40 owing to their occupation. These men work in industrial chemical laboratories or factories and are continuously exposed to the risk of chemical burns. The home environment also contains chemicals in the form of cleaning products.
Alkali often causes the most severe damage to the eye compared to acids. A lyre is an alkali substance commonly found in dishwashing detergents, concrete, fertilizers, mortar, oven and drain cleaners, lime products, and plaster. Severe burns affecting the cornea can cause infection, perforation, scarring, and even blindness.
Although burns caused by acids are less severe, hydrofluoric acid is equally as dangerous as an alkali substance. Examples of acidic substances at home include nail polish remover, automobile battery, and glass polish. Irritants contain a neutral pH and will be found in household detergents and pepper sprays. They only cause discomfort and do not damage the eye.
Signs & Symptoms
Common signs and symptoms elicited from chemical burns may include:
- Red eyes
- Lid swelling
- Blurry vision
- Sensitivity to light
- Excessive watering
- Foreign body sensation
- Pain which is often severe
- Stinging, burning sensation
- Inability to keep the eye open
- Loss of vision (from very serious burns)
- Increase of intraocular pressure or glaucoma (can occur later)
Medical history from the patient is significant. The eye doctor wants to know which chemical was involved and the mechanisms behind the injury.
Tests and examinations may include:
- The eye doctor irrigates the eye through flashing with saline or plenty of fresh water
- The patient undergoes a full eye examination to establish the extent of damage and burn location. The examination includes the use of an eye chart to determine visual acuity. The doctor also checks the surrounding structures and carefully examines the eyelids
- Diagnostic testing such as a fluorescein dye to color the eye and view the eye under ultraviolet light to determine the extent of the injury
- Often because it takes about 24 hours to know the full extent of the burn, the patient will need to come back for a follow-up examination
Treatment is aimed at restoring the normal ocular surface anatomy and function. It varies depending on the extent or grade level of the burn.
The first line of treatment for the individual is prompt first aid which includes:
- Remove the contact lenses as soon as possible (if they were worn)
- Use running water on the face for about 20 minutes. The patient uses fingers to hold the eyelids apart while the water stream floods the eye
- Seeking immediate medical advice
- If acid or alkaline is involved, the patient should visit the nearest clinic. Alkaline chemical burns may not show symptoms but are the most dangerous. Powder chemicals are hard to flush out, hence the need for a doctor.
Medical treatment may involve:
- Pain-relieving drugs
- Anti-inflammatory medications
- An eye patch is worn until recovery
- Hospital admission for very serious cases
- Topical antibiotics to address possible infection
- Lubricants to keep the lids apart from the cornea during the healing process
Surgery is considered in more severe burns. Depending on the severity, the eye can become visually impaired or blind. Surgery should be done within 24 hours to prevent serious complications and preserve vision. Surgical treatment options may include:
- Corneal transplantation
- Limbal stem cell transplantation
- Amniotic membrane transplantation
Prognosis & Long-Term Outlook
Mild burns often do not need medical interventions and will be cleared by saline or a steady flow of water. Minor burns can also be adequately addressed medically. Serious burns (Grade III and specifically IV) are ocular emergencies and must be treated immediately. Depending on the time taken to seek medical attention, the type of chemical burn, and severity, the eye may be restored to its normal anatomical structure and function.
However, complications may include:
- Corneal ulcer
- Corneal perforation
- Visual impairment or blindness
Prevention & Follow Up
Chemical burns require frequent follow-up, depending on the degree of burn. Research indicates that 90% of chemical burns can be avoided by using appropriate safety gear which may include:
- Face shields
- Safety glasses
- Safety goggles