activity. Called irritation, this process is due to an increased release of vasoactive substances, proinflammatory mediators such as IL-8 (Interleukin) and VEGF (Vascular endothelial growth factor). These mechanisms offer the possibility of cleavage of wounds, removal of necrosis, and installation of healing tissues. This temporarily increased biochemical activity is regulated and is stopped by inhibitors of inflammation released from closed cellular epithelium when healing is achieved. The result of an irritation is a healing “ad integrum.” In contrast to this, burns are defined as a trauma that is not self limiting. Thus additional measures such as medical wound cleavage, a surgical removal of necrosis, and an initiation of healing must be done. Furthermore, an efficient modification of the inflammation is required by means of steroids and nonsteroidal compounds. Only under these circumstances, healing or regulated scar formation can be achieved.

Figure 5.12a shows the impregnation of a cornea with 1 mol NaOH over the time of exposure. In Fig. 5.12b, image shows the impregnation speed for some 2 mol NaOH. There is a considerably higher invasion speed of the corrosive depending on concentration over time. Thus the integral of concentration over time gives an answer to limits between irritation and burn.

The disease of burn is characterized by an overwhelming inflammation, with invasion of leucocytes within the whole tissue without any modulation of tissue breakdown, and an ulceration of the necrotic tissues.

Delayed intervention results in much more severe damage to the eye [6].

5.2  Pathophysiology of Eye Burns1

5.1.6  Eye Burns

Eye burns are a process that develops during a chemical or thermal exposure that is of exceeding mass, contact time, chemical reactivity, and temperature until the exhaustion of the protective mechanisms of the eye. The most plastic description of this process can be given in images that are obtained by optical coherence tomography [5].

5.2.1  Types of Burns and Eye Irritation

The expressions of eye irritation and eye burns define a variety of interactions of chemical fluids, powders, and foreign bodies when they interfere with the ocular surface [7]. In this chapter, we shall focus on the mechanistic understanding of the known facts in this field.

1Dedicated to the 75th anniversary of Prof. Dr. med. M. Reim, a great researcher and teacher in Ophthalmology and especially in the research and clinical work on eye burns.