Several methods are known for the diagnosis of infections all of which require the use of well equipped laboratories and skilled personnel. For example: 1. Isolation and culturing of microorganisms from samples taken from body fluids. This method is complicated and time consuming. 2. Detection of antibodies. The main disadvantage of this method is the fact that the change in the level of antibodies occurs only after a few days from the onset of the disease. In the course of our work we found that already in the early stages of acute external eye infections, mucopolysaccharide degrading enzymes (MPDE) appear in tear fluid, where they are normally not present. We also found a relationship between MPDE with different infectious diseases of the eye as well as their role in the progress and treatment of these diseases. As a result of these findings and numerous clinical and laboratory in vivo animal and in vitro experiments, we developed a new approach for early detection of acute ocular infections. Utilizing this approach based on tear samples from patients; eyes, we developed a method which enables quick and reliable detection of the presence of an infection in general, and for early diagnosis in particular. Testing MPDE in tears with this method revealed also a new phenomenon of specific geometric imprints, or orthographic signs, each of which may be indicative of a different type of acute infection, e.g. adenovirus, herpes simplex virus-1, or other acute viral and bacterial infections.(ABSTRACT TRUNCATED AT 250 WORDS)