Ten years ago Susan Dunn was, as she phrases it, "on her way to an ordinary life" when a fall from a horse turned her world upside down. The accident caused her eyes to hemorrhage and, aggravated by the diabetes she had had since childhood, her sight gradually worsened until five years later she became totally blind.

She was 21 when the accident occurred in the midst of her life of teaching, acting and dancing. The greatest fear, she said, was "losing touch, losing communication with the world."

Dunn has broken through that fear with an extraordinary play about her experience entitled, "The Drummer I Must March To?" which is being presented at the University of Maryland this week. Author Dunn will also perform, along with six students from the university's theater division.

The play's title came from the four months Dunn spent in Arkansas at a rehabilitation center for professional people who were blind. Dunn went through the training with a blindfold because she could still see at that time. t

"I'd never been exposed to a blind person before for any length of time," said Dunn. "Everyone was deep into cane technique because that was independence, being able to walk with a cane and not having to hang onto somebody."

The courtyard of the Arkansas center, where the trainees practiced their cane technique, was filled with the sound of constant tapping.

"I sat there, seeing all these things happening," said Dunn, "and I wondered if the rest of my life would be spent tapping along with these people."

She put these thoughts into a short piece: I've tried to ignore the tapping of canes But something inside caused me to hear them, And like the beating of your heart in a death cell, They blot out all other sounds. Is this the drummer I must march to?

She was a long way from thinking of herself as playwright. "Writing was therapy, something better to do than beating my head against the wall or biting my nails," said Dunn.

Over the next few years she continued to record her reactions and those of her family, her friends and people at large as she gradually entered the world of the blind.

"I wanted a record for myself," said Dunn. "There were emotions that I didn't want to lose."

In 1970 she went back to the University of Maryland, from which she had received her degree in elementary education, to take more theater and dance classes. There she met Ronald O'Leary, head of the theater division. d

This past June, when she decided that it might be possible to put the pieces together in a play, Dunn remembered O'Leary and his encouragement. She sent him a manuscript. Within a week he called to say that the play had production possibilities.

Then, said Dunn, the work began.

"I had visions of giving him the manuscript and then coming back sometime later to see a show. No way. I had to do lots of writing, giving some dramatic sense to the material."

With O'Leary's guidance Dunn gradually shaped a theater piece that mixes word, song, dance and mime. Subtitled "a young woman's journey into dark and light," the play traces with poetic insight the years of Dunn's growing blindness.

In lines of compelling directness she articulates, for example, the bewilderment she felt when everyone, even her family, no longer seemed to see her as a three dimensional person: Suddenly I am diffeent, Not Susan anymore, Although I must admit I feel no change . . . I'm still me looking out But what do they see, looking in?

And there is humor -- sometimes bittersweet, always pointed. To end a spirited passage proclaiming her ordinariness, Dunn comes up with "Helen Keller is too great a cross to bear."

Dunn's appearance in the play marks her first performance since becoming totally blind. Devising a few systems to help Dunn with her orientation onstage, the company soon learned that, as her fellow actress Kathryn Silvia put it, "there's no reason she can't look like us up there." In fact, the opening of the play is so designed that the audience does not know at first which person is Dunn.

Blindness has affected Dunn's view of life. "I think this experience has made me feel more strongly that we must overlook the differences that might separate us and deal with the human being, the god, that is in each of us," she said. "We're all human beings under the clothes, the prejudices, the braces, whatever. We're wasting so much time being put off by these outward covers that we wear."

"The Drummer I Must March To?" will be at the University of Maryland in a workshop production tongith through Saturday. Anyone interested in the few remaining tickets should call the Tawes Theater box office at 454-2201.