Fig. 5.12  (a) Impregnation speed of a cornea with 1 mol NaOH and (b) impregnation speed of a cornea with 2 mol NaOH

a

b

The most important knowledge in this field is to be found in experiments that have been performed within the last 20 years in a systematic approach on explaining circumstances of eye burns, systematic evaluation of types of corrosives, and the evaluation of corrosives in organotypic experiments.

The newer efforts of the European community with the REACH initiative and the prohibition of animal experiments for the allowance of cosmetics lead to a new systematic approach on the understanding of the mechanisms of eye irritation and the related eye burns.

In clinical understanding, we find typical and different patterns of eye irritations and eye burns. The origin of all clinical appearance is always related to damage to the structure as known from strong alkali and strong acids. There are also specific interactions with loss of calcium in case of fluoride ions leading to a complete stop of cellular life within seconds to not yet welldefined interactions of peroxides and oxygen radicals with membranes, leading especially to proinflammatory cellular response. Other types of eye burns relate to membrane active irritants as typically known from detergents of different types like anionic, cationic, and

nonionic [8]. Severe burns also result from other substances (such as reducing agents, alkylating agents, solvents, ionizing chemicals, etc.) that are mostly known from accidents in heuristic cases and case collections of clinical treatment [9].

5.2.2  Mechanisms of Corneal Burns

5.2.2.1  Contact Mechanisms

The first contact of a corrosive with the eye surface is normally with the skin when eyes are closed and the propagation of the corrosive into the tear fluid is done by lipid transport from the skin surface into the tear film well known as from the inner lid angle and about 2 mm zone out of the lid margin. Other mechanisms of delivery to the eye itself are smearing from fingers, direct projections such as drop-like splashes and shallowing of low pressure or “bathing” to beams of high pressure as typically known from opening of tubings with high hydrostatic pressure, pumping stations, or