Definition
Eye burns are the damage of eye structures by different chemical substances. Depending on the duration of exposure, strength and type of the chemical, burns of varying severity can occur, which can be divided into several stages. In any case, the chemical burn of the eye is an acute emergency requiring immediate first aid measures directly at the site of the accident and medical treatment. The affected eye must be rinsed out immediately, as eye burns can lead to serious damage such as blindness or loss of the eye.
Causes of eye burns
Burns to the eye can be caused by contact with acids or bases. Acid burns can be caused, for example, by liquids from the chemical industry, car batteries and household and occupational acids. Bases are found in cleaning agents and also in lime.
Also adhesives can cause chemical burns. Most chemical burns occur while handling harmful substances at work, but eye burns can also occur during leisure time. The majority of patients are young people who suffer burns as a result of accidents at home or at work.
Attacks with acids and alkalis are another reason for eye burns. Depending on which acid or lye gets into the eye, the process of chemical burns takes place at different speeds. Acids and bases both lead to the destruction of the outer structures of the eye.
They do this via different mechanisms of action. Together with burns, chemical burns account for approx. 8 -18% of all eye injuries.
Due to the hydroxyl ions (OH- ions), the bases lead to damage of cell membranes and thus to the destruction of the affected cells. Furthermore, the cationic (positively charged) part of the base initiates the destruction of epithelium (superficial protective cell layer) of the cornea and conjunctiva as well as the supporting connective tissue. This means that all outer cell layers of the eye are attacked and destroyed – a liquefaction of the protective outer cell layers takes place (colliquative necrosis).
As a result, the base ultimately also reaches the inner areas of the eye. Here the pH value increases due to the OH- ions that have penetrated. This ultimately leads to the destruction of the deeper structures of the eye: the ciliary body, the iris and the lens.
Acids act through H+ ions (protons). These cause the natural proteins of the eye to lose their original function and structure (conformation). This process is called denaturation.
Due to the loss of function of the proteins, the cell at the eye also loses its function. The cells and proteins perish and form an association of interconnected and clumping cell remnants, which is called coagulation necrosis. This agglutination results in the formation of a kind of new protective barrier that prevents the acid from penetrating into deeper layers and causing damage. Therefore, weak to medium strength acids tend to cause more superficial damage. Strong acids, however, overcome the barrier formed by coagulation necrosis and also attack deeper parts of the eye.