Acute ocular burns are an important ophthalmic emergency. The severity of burn injuries depends on multiple factors, including the agent that caused the burn (in fact, burns are not caused by fire alone), the duration of exposure, the surface area affected and which ocular tissues are involved. Larger burns of the eye and ocular adnexa cause severe morbidity and can have long-term consequences on both vision and quality of life, as they can cause sequelae such as chronic pain, scarring, loss of the normal function of protective adnexa and permanent loss of vision. The latter is also associated with a high risk of future injuries, depression, chronic diseases and other serious health and psychological problems.
What are the possible causes of eye burns
Burns of the eye and ocular adnexa can be divided into two general categories, thermal and chemical. There are important distinctions between these two categories and in the way the injury progresses.
- Thermal burns
Tissue damage from thermal burns, due to heat sources or fire, stops progressing rapidly once the heat source is no longer in contact with the patient. This is a mechanism put in place automatically because one tends to move away from the heat source and the eyes activate the blink reflex. The ocular adnexa also protect the eye, so the greatest damage is often found in the eyelids. Direct thermal burns to the ocular surface generally cause superficial injuries due to the short contact time. The most common causes of ocular thermal burns include hot water, hot cooking oil, curling irons and fire, e.g. from an explosion or fire. These types of burns can be managed in the same way as other superficial corneal injuries.
- Chemical burns
In the case of chemical injuries, however, tissue damage may persist and extend deeper into the ocular structures as long as the chemical remains in contact with the eye and ocular adnexa. Therefore, chemical ocular burns require prompt intervention to remove the insult and prevent continued damage to the ocular surface and deeper structures. Chemical burns can occur from exposure to everyday household products such as drain or oven cleaners, laundry or dishwashing detergents, bleach and ammonia. Injuries can also occur from exposure to substances such as fertilisers, industrial acids, lye, lime and cement.
The incidence of ocular burns is not fully known however, according to two US databases, the American Academy of Ophthalmology (Academy) IRIS® Registry (Intelligent Research in Sight) and the Nationwide Emergency Department Sample, ocular chemical burns cause between 11.5 and 22.1% of ocular injuries.
How to intervene in case of eye burns
In the treatment of ocular burns, the first step is immediate and complete decontamination of the ocular surface with a sterile solution, if available, or with tap water. The washing, called 'irrigation', must be timely and continued in the hospital. For a minor injury, as much as 2 litres of sterile solution may be needed. This serves to restore the pH value of the eyes to the correct value, between 7.0 and 7.2. Severe injuries may require 2 to 4 hours of continuous irrigation for adequate decontamination. Topical anaesthesia may also be required during the process. Once irrigation is complete, it will be ensured that no particles are present in the eye, which must be removed.
Management during the acute phase (0 to 7 days) and the early reparative phase (8 to 21 days) is aimed at suppressing inflammation and promoting regeneration of ocular surface tissue.
Treatment involves the use of topical antibiotic ointments and preservative-free artificial tears, in the case of mild lesions. Topical steroids may be administered to reduce inflammation in more severe cases. During the acute phase, systemic pain-relieving drugs may be needed in addition to topical therapy. Medications to reduce intraocular pressure may also be needed throughout the continuum of care. Indeed, elevated intraocular pressure can impair corneal healing in the acute and early reparative phases and must be treated promptly, as it can damage the optic nerve.
More severe burns will require more specific therapies, such as topical biological drugs, e.g. platelet gel, and the application of contact lenses with bandages may be necessary. More severe burns may require early amniotic membrane transplantation, preferably during the first week.
During the last phase, the so-called late reparative phase (>21 days), management involves control of the inflammation, rehabilitation and reconstruction of the ocular surface. If necessary, different types of keratoplasty (i.e. corneal transplantation if irreversibly damaged) are available, depending on the depth of the corneal scars. The aim of keratoplasty is to improve visual function.
How to prevent eye burns
Burn prevention must be ensured both at home and in the workplace.
To prevent injuries in the home, especially in children, it is necessary to limit the access of children to dangerous chemicals.
Workplace accident prevention, on the other hand, requires appropriate personal protective equipment, to be used when handling chemicals, and workers' knowledge of the substances they are working with. On-site decontamination measures are required by law and workers need to know where they are and how to use them in case of exposure. Regular training on hazardous materials should also be offered, including decontamination techniques, where exposure to hazardous chemicals may occur.