No one knows when the damage occurred that led to Sugar Ray Leonard's career-threatening eye injury, but referee Davey Pearl, who officiated at the Leonard-Thomas Hearns welterweight title fight in September, saw something that night that worried him.

"I didn't like it when I saw it," said Pearl of the discolored, half-closed left eye through which Leonard peered at his taller opponent much of the bout. On Sunday, doctors repaired a partially detached retina in the eye, a serious operation that forced cancellation of a scheduled title defense Friday and gave rise to speculation that Leonard, the richest boxer of all time, might never fight again.

Pearl had handled a fight 28 months earlier in which an eye injury led within days to surgery to repair a detached retina. With that experience in mind, he watched Leonard closely from the time the boxer stepped into the ring to face Hearns. Pearl said he noticed a slight swelling of the eye, apparently from an elbowing incident in training. As the fight progressed, the swelling worsened.

"I refereed a (May 20, 1979) fight between Hearns and Harold Weston in Vegas," Pearl said, "and Weston couldn't go on after the sixth round. His eye closed up about the same way as Leonard's and he had surgery" for a detached retina.

Weston's surgery, days after the fight, salvaged his sight, but he never fought again.

Weston's eye "closed up, but not as much as Ray's," said Pearl. He said he watched Leonard "to see if the eye would close completely and it didn't. If it had closed any further I would have taken him over to the doctor for a recommendation" on whether to let the fight continue.

Leonard beat Hearns on a technical knockout in the 14th round to win the undisputed world welterweight title, Pearl halting the bout on grounds that Hearns was defenseless. Pearl said yesterday he was not surprised to hear of Leonard's developing an eye problem, "But I did think that after all this time it was unlikely to happen."

Leonard's attorney, Mike Trainer, discounted speculation the injury stemmed from the pounding the eye took in the Hearns fight. If it had, Trainer said, "He'd have had symptoms long before now. Ray had no problem with his eye" until the last two weeks, Trainer said, adding that "it's far more likely that it (the damage) happened in sparring."

Trainer said the nature of the injury--which never impaired vision, but created a distraction as a "spot" occasionally appearing in Leonard's field of vision--indicates "it couldn't have been there that long."

"Ray's injury wasn't that severe," said Trainer. "It was just sensationalized because of who he is. He had no vision loss. It's actually amazing it was picked up at all."

Leonard's manager, Angelo Dundee, said when he arrived in Buffalo May 3 to supervise final training for the scheduled defense against Roger Stafford, no one in Leonard's camp mentioned eye trouble.

But last week Leonard "cried to (trainer) Janks (Morton) he was seeing a spot," Dundee said. Leonard went to an eye specialist in Buffalo, who found no problem and prescribed eye drops. When the spot remained, Leonard saw a second specialist, who detected retinal damage and recommended more sophisticated testing. On Saturday, Leonard flew to Baltimore for a visit to Johns Hopkins, where the surgery took place.

Two boxers who had retinal detachments said their injuries developed over time. Adrian Davis, a local ex-boxer and coach who is blind in one eye after four operations to correct retinal detachment, said, "The doctor told me you never know exactly when it happened." Instead, there is a slow deterioration, Davis said, "until you wake up one day and say, 'What's going on?' "

And Weston, now a matchmaker at Madison Square Garden, said although he had no previous history of eye trouble, when he saw a specialist after his fight with Hearns, "He told me there had been a problem for many years, over the course of many fights."

Weston said he has researched the injury so thoroughly "I'm practically a doctor myself in detached retinas . . . If you took all the fighters today and gave them serious eye exams, you'd find probably 30 to 40 percent have partially detached retinas. It's a very delicate thing."

Yet in his 40 pro fights, Weston said, no prefight physical ever included an inspection of his retinas.