You may not have heard of World Glaucoma Day - March 12 will be only the second - but that doesn't mean it's not needed.

"Bottom line is, glaucoma is a very prevalent disease," said Dr. I. Paul Singh of the Eye Center of Racine.

"There are probably 70 million people who have it worldwide," said Dr. Paul Kaufman, chairman of the Department of Ophthalmology and Visual Sciences and a glaucoma researcher at the University of Wisconsin School of Medicine and Public Health.

Glaucoma is a group of diseases that may damage the optic nerve, which carries signals from eye to brain.

"It's actually the second leading cause of blindness in the world, third here in the united states," said Singh.

"The older you are, the more likely you are to have it," Kaufman said. "And it's race related - very strongly."

A person who is 75 and white has about a 5 percent chance of having glaucoma, he said. A person who is black and 75 has a chance of between 10 and 12 percent. Someone who is Afro Caribbean - whose genetics are closer to those of Africans - has a chance of about 20 percent.

It's also a quiet disease. People can lose up to 30 percent of a nerve before they notice any vision problem because the change is so gradual, Singh said.

Doctors know what the problem is: pressure inside the eye. It's both an indicator of disease and the cause of nerve damage. What they don't know is exactly how pressure relates to damage.

People may have normal pressure and have glaucoma, Kaufman said, or they may have abnormally high pressure yet show no sign of disease. Doctors measure eye pressure during an exam, but that's only one fraction of a moment in time, he said. They don't know how pressure varies over the course of a day or month.

Even if the nuances are unclear, there are new and much improved treatments. In part that's driven by the need to make care more convenient for patients so they comply with treatment, Kaufman said.

"Nowadays most people are doing so well on drops alone, we're happy," Singh said. Those have become much safer and more effective compared to the past, he said, and the typical dose is only one drop a day. There are other tools in a doctor's kit.

One thought about the cause of glaucoma is that the eye's drainage system (the trabecular meshwork) becomes blocked which allows fluid to build up inside the eye, Singh said. Light pulses from a laser can stimulate those drains to open. A newer technique is just like the angioplasty performed on heart patients; a doctor uses a very thin wire to open the drainage holes. Yet all of this emphasizes only the management of pressure within the eye.

"Right now there is no medication on the market that targets the optic nerve," Kaufman said.

The glaucoma research unit is the largest part of his department in Madison, he said, and research is just beginning to look at ways to strengthen or reinforce the damaged nerves. And of course it's not just one nerve but millions of fibers running through the eye and combining into a single cable.

Treatments are useless, however, unless people know about the problem. The National Eye Institute did a survey in 2005 and 2006 and found that three-quarters of the people surveyed said losing their sight would have a great affect on their lives. But how many knew that glaucoma has no early warning signs? Just 8 percent.

If You Go

What: The Eye Center is offering free glaucoma screenings along with a lecture on the disease by Dr. I. Paul Singh.

When: From 5-7:30 p.m., March 12.

The lecture will start between 6 and 6:30 p.m.

Where: Eye Center of Racine, West Professional Building, 3805 Spring St.

Reservations: Required for the screening. Call (262) 637-0500, or register online at: http://amazingeye.com