In a breakthrough in Alzheimer's disease research, American doctors have converted a simple eye test into a powerful diagnostic instrument for the disease (Science, Vol 266, No 5187).

A research team led by Leonard Scinto and Huntington Potter of the Harvard Medical School, Boston, reports that the pupils of Alzheimer's patients dilate more pronouncedly -- 13 per cent or more -- in response to drops of tropicamide, which doctors use in routine eye examinations, compared to about 5 per cent observed in healthy elderly people. The scientists claim that their test may be able to predict potential victims even before the symptoms develop.