A research team headed by Dr. Andreas Stang and Professor Karl-Heinz Hoeckel of the University's Institute for Medical and Computer Science found that the incidence of eye tumors in a normal population is around one in 100,000 every year.

However, after interviewing 118 people with uveal melanoma and comparing their mobile phone usage with a control group of 475 people without the cancer, the researchers found a higher incidence of eye cancer among the regular mobile phone users than those that did not use a cellular phone.

To prevent any statistical bias, the researchers were not told who had, and who did not have, eye cancer. In this way, Dr. Stang says, the results were as unbiased as possible.

In his report on the research, published by the university, Dr. Stang was at pains to stress that the findings should not be treated as conclusive.

"Whether the high frequency radiation of mobile phones actually promotes the development of uveal melanoma or not cannot be finally answered," said the report, adding that further scientific investigation will be required to support or disprove the theory.

Previous research into uveal melanoma has suggested that cells within the uveal layer, a layer of melanocyte cells behind the retinal layer of the eye, will grow and divide rapidly when exposed to high frequency radiation, such as that from a microwave.

Because of this, Dr. Stang and his colleagues set out to research whether the same was true for the use of mobile phones.