In spring and summer, many people go about with bloodshot eyes and runny noses. The hay-fever season is upon us. Nasal sprays or eye drops provide relief in mild cases: one drop in each eye, and the urge to rub one's eyes disappears. But many tests are required before such a preparation can appear on the market. The law in most countries forbids the sale of cosmetics and medicines without exhaustive information on their effects and possible side-effects. In many cases tests on live animals are unavoidable; yet there are methods that can avoid this suffering. One such is based on an artificial cornea developed by researchers at the Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB (Fraunhofer Institute for Interfacial Engineering and Biotechnology) in Stuttgart. This can be used to test the irritant effect of a wide variety of chemical substances, and also complete cosmetic and medicinal products.

The cornea is made up of three different types of cells - endothelium, stroma, and epithelium. In order to produce a functioning model, all three types have to be grown in the laboratory. "The starting material was corneas from pig foetuses which we obtained from the abattoir", explains Dr Thomas Graeve of the IGB. "We extracted all three types of cell from one cornea and placed them in a suitable nutrient until they had multiplied to form a largish cell culture." The scientists then had to build up a three-dimensional model, an in vitro cornea, which corresponded in structure and physiology to the cornea of a real eye. Only then could the irritation tests be carried out. Trials with a series of substances showed that this artificial cornea could replace to a large extent the Draize test normally carried out on live rabbits. Some pharmaceutical companies are already using this humane alternative. So as to be able to soothe even more inflamed human eyes, various preservatives for eye drops and ointments have been tested for compatibility using the artificial cornea.