Enzo Maccarinelli (L) of Wales fights with an injured eye during his WBA light heavyweight title fight against Juergen Braehmer on April 5, 2014 in Rostock, Germany. (Photo by Boris Streubel/Bongarts-Getty Images)

Just days before their much-ballyhooed 1987 match, the richest prizefight in history at the time, the meeting of Marvelous Marvin Hagler and Sugar Ray Leonard in a middleweight championship bout was suddenly cast in doubt.

It was a question of doctors seeing eye-to-eye.

Or more precisely, the condition of Leonard’s left eye.

Five years earlier, Leonard had undergone surgery to repair a detached retina in his left eye. His bout with Hagler would be only his second since that surgery and there were serious questions about whether it was medically wise to put his repaired eye (and vision) at risk. Hagler, after all, was bigger, stronger and a 3-1 favorite.

A few months earlier, a panel of ophthalmologists had pronounced Leonard’s left eye fully recovered. He was fit to fight, they said. But with the bout looming, other doctors expressed doubts and demanded that Leonard undergo a new eye exam.

“I don’t see what the controversy is all about,” Dr. Louis Angioletti, one of the ophthalmologists who had examined Leonard, told the Philadelphia Daily News at the time. “Ray Leonard has no greater risk of developing a retinal detachment on Monday night than any fighter on the card.”

Indeed, asserted Angioletti, Leonard was “at no greater risk of sustaining an eye injury than any boxer.”

Which is not to say he was at no risk.

Among the myriad ways a boxer can be hurt, eye injuries are neither the most likely nor most worrisome. The chances and consequences of brain trauma are far more troubling. But the risk of eye injury in the ring is quite real and worthy of concern.

In many ways, boxers’ eyeballs are at similar risk as their brains. Both are essentially bags of water – the brain 75 percent, the eyes 95 percent – protected by surrounding bone, the skull and the orbit or eye socket, respectively.

Though its bones are relatively thin, the orbit is surprisingly strong. And in conjunction with the adjacent bones of the brow and cheeks it provides substantial protection from most boxing blows, depending upon their angle of attack.

The greatest threat of injury comes from the blow a boxer sees coming: a punch directed into the front of the eye. There is no protection if struck dead-on, particularly if the blow is delivered by the thumb portion of the glove, which can focus more force into a smaller, more penetrating area.

Eye injuries typically occur through three mechanisms.

The first are sometimes called “coup” injuries, the direct consequence of the punch itself. Doctors sometimes refer to them as traumatic glaucoma.

In a healthy, uninjured eye, a transparent fluid known as the aqueous humor fills a space between the cornea and the lens at the front of the eye. It provides structural support and nutrition to surrounding tissues and is constantly being replenished, with excess fluid flowing out of the pupil to be reabsorbed into the bloodstream through a meshwork of drainage canals around the outer edge of the iris.

A blow to the eyeball can damage this system, in particular the ciliary body – the part of the eye that produces the aqueous humor. Hemorrhaging inside of the eye can result, clogging the drainage system, increasing eye pressure and ultimately harming the optic nerve and the ability to see.

The second mechanism involves so-called “contrecoup” injuries, which occur when the force of the impact traverses the eyeball like a ripple through a water balloon. Damage occurs where tissues of different densities connect. One result can be cataracts (clouding of the lens), though the damage might not become obvious until years after the original injury.

A third mechanism of injury is known as equatorial expansion. As the globe of the eye is compressed by a blow, pushing the front portion toward the back, the circumference of the eye’s equator increases. Think again about that water balloon. If you push on opposing sides, the balloon will bulge in the middle. The same thing happens with punched eyeballs. The outer covering – called the sclera or white of the eye – stretches and pulls away from underlying, attached tissues. The result: torn or detached retinas which, without treatment or surgery, are likely to result in diminished vision or even blindness.

Eye injuries are common in boxing, though exactly to what degree, it’s hard to say. For obvious reasons, they do not attract the same scientific scrutiny as, say, brain trauma. (And some would argue that brain trauma in boxing is grossly under-studied.) Nonetheless, there are some data.

A year before the Hagler-Leonard bout, for example, researchers at the Manhattan Eye, Ear and Throat Hospital published a study in which they examined every seventh boxer applying for a new or renewed license to fight in New York State between 1984 and 1986.

Seventy-four boxers were randomly chosen for eye exams. Most of them reported no problems with or history of ocular damage, but upon examination, doctors found that 66 percent of the 74 (49) showed evidence of at least one eye injury, spanning the gamut from drainage abnormalities and macular lesions to cataracts and retinal tears. The more bouts a boxer had under his belt, the researchers said, the more likely he had suffered eye injury, particularly once they passed the 50-fight threshold.

More recently, a 16-year study of professional boxers in Australia, published in 2003 in the British Journal of Sports Medicine, found that 107 injuries were recorded in 427 fights. The most commonly injured region of the body was the head/neck/face (89.8 percent), with injuries to the eyes accounting for 45.8 percent of that total. Most of these injuries were superficial (cuts, abrasions, bruising, swelling) but roughly one-quarter involved injury to the eye itself.

Sometimes the injuries produce dramatic, even tragic, results. Middleweight Gerald McClellan lost his eyesight after being severely beaten in a 1995 match with Nigel Benn in London. In 2010, welterweight Antonio Margarito suffered a severely fractured right orbital bone in a bout against Manny Pacquiao. The injury led to a pair of surgeries.

As with Leonard in 1987, boxing officials ordered Margarito to undergo an eye exam before sanctioning a rematch with Miguel Cotto in 2011. Margarito passed the eye exam but lost the fight when a ringside physician stopped it after 10 rounds, ruling the boxer’s previously injured eye was swollen shut and he could no longer see well enough to defend himself.

Still, few boxers give up their careers due to eye injuries or vision concerns. In 1987, despite public concerns about risk to his vision, Leonard did fight Hagler – and he won.

Apparently, only Leonard saw it coming. This magazine later declared the bout to be the “Fight of the Year” and eventually the “Upset of the Decade.”

Earlier this year, it was reported that Margarito too was considering a comeback. Some may favor the idea, but the eyes say no.

 – Scott LaFee