Flashing lights. Dancing patterns. Red beams.

A Georgetown University Hospital patient watches the images on a television-like screen, and every movement of his eyes is transmitted to a computer that swiftly compares the eyes' movements with the brain's responses.

The result, a set of dots that form curves representing responses of the eyes and the brain appears on another glimmering screen in a nearby room.

Doctors studying those curves say the new computer developed by Georgetown University Hospital has enabled them to diagnose early multiple sclerosis in 10 patients only suspected of having the debiltating disease of the central nervous system. After studing 300 patients tested by the computer, they say the machine promises to become an important new tool in diagnosing a variety of brain, nerve and eye diseases.

It might help physicians spot the early signs of such serious nervous system disorders as Huntingtons' chorea, myasthenia gravis, Parkinson's disease, stroke and many other mysterious forms of coma, as well as eye diseases such as neuritis (or nerve inflamation) and optic nerve tumors.

Although there is no effective treatment now for many of the disorders being studied, scientists said early detection may lead to better understanding of the causes and, eventually, to better treatment of the mysterious diseases.

The new computer system was unveiled this week at Georgetown. It was developed by Dr. Robert S. Ledley, the Georgetown scientist who in 1973 invented the whole-body CAT scanner, a computerized x-ray machine that gives doctors a three-dimensional view of any part of the body. The first CAT scanner, which was limited to studying the brain, was built by Dr. Godfrey Hounsfield of Britian who last month shared a Nobel prize for his work.

The CAT scanner has become a controversial tool because of its cost, which ranges from $200,000 to $1 million. Health planners say uncontrolled sale and use of the expensive machines has contributed to rapid inflation in the health-core industry.

Georgetown's new machine, to be manufactured by Pfizer Inc., which financed its development, could be marketed for about $60,000 Ledley said. That means it could be within reach of private neurologists and eye specialists for use in their own offices.

Ledley explained how the new machine, called a Computerized Electro Neuro-Opthalmograph, or CENOG, works.

The eye reflects events in the brain and the nerves. Ledley said. The brain reflects events in the eye and influences the eye's reactions to what it sees.

Ledley said researchers using the CENOG expose the eye to light in various forms. The retina, the seeing part of the eye, is basically all nerve endings, and "when the eyeball turns in response to our stimuli, there are voltage changes between the electrodes that we place on the patient's skin" around the eyes, he continued.

"First, the eye sees something. Then a nerve impulse goes to the brain. The brain processes the impulse. Another nerve impulse comes back to the eye muscles. The eye moves. And if there is any disease or injury (in the eye or the brain) you detect an adnormal reflex motion," he said.

Many present tests designed to diagnose nerve conditions require injection of dyes or radioactive chemicals into the body. And many are inexact.

"What we have here," Ledley said, "is a painless, noninvasive diagnostic technique, and one that not only tells you a condition is there but tells you in quantitative terms, in exact measurements. In neurology, diagnosis is often difficult. We think this will make it easier."

Dr. Jorge Kattah, a neurophthalmologist and Ledley's collaborator, conceded there is no effective treatment today for many brain and nerve conditions. "But if we can detect them earlier," he said, "we may learn more about their cause and their best treatment."