The microprocessor, the so-called "computer-on-a-chip," is providing automation of many of our diagnostic instruments, including refractors, keratometers, lensmeters, and perimeters. Microprocessors can monitor switches, control lights, drive motors, and perform complex mathematical calculations in a fraction of a second. These capabilities promise a standardization of measurement never before possible. Clinical tests will soon not only use instruments controlled by computers, but the tests themselves will be administered by computers. Cost:benefit ratios are decreasing as this new technology becomes an expected part of ophthalmic practice.