Cliff Kyle first noticed his vision loss in 2010 after he got into a bike accident because he didn’t see another cyclist come up behind him during a 100-mile race.

That was his last outside ride. In the two years after that bike accident, Kyle’s glaucoma progressed so quickly that he lost 60 percent of his vision and was declared legally blind.

Kyle, 67, had known he had high pressure in his eyes since 1992, when he was 42. But glaucoma was so far out of his mind that he often went months without refilling his prescription for eye drops that he doctor gave him. He wishes he had.

“Here’s some advice,” Kyle, an associate pastor at Rock of Our Salvation church on Chicago’s West Side. “Take glaucoma seriously and take your medication.”

Most people don’t know they have the disease, because, like Kyle, they have no symptoms. It is known as “the silent killer of eyesight.”

That’s because glaucoma usually is not detected until a doctor notices it during a regular screening or a person loses her vision. Vision loss cannot be restored and there is no cure.

“Life in 2012 was horrible for me,” Kyle said. “I lost my independence. I couldn’t drive. I couldn’t ride my bike outside. When you can see at one time, but then suddenly you can’t see — it’s pretty devastating experience,” he said.

More than 3 million people in the United States have glaucoma, but only about half know they do, the Glaucoma Research Foundation (www.glaucoma.org) reports. It is the leading cause of blindness in the country.

That number, said Michael Savitt, an ophthalmologist with Rush University Medical center, is increasing. But that’s because people are living longer and because tests can now pick up the disease at its earliest stages.

“Years ago, we could only wait for vision field loss. But it’s an exciting time now for treating glaucoma,” says  Dr. Michael Savitt, an associate professor of ophthalmology who specializes in the treatment of glaucoma. |  Rob Dicker/For the Sun-Times

“Years ago, we could only wait for vision field loss,” he said. “But it’s an exciting time now for treating glaucoma.” Early detection is key to preserving eyesight, he said.

“When it comes time to get a diagnosis, people are very fearful,” Savitt said. “However, the great majority of time, people do not go blind. For a majority of the time, they can manage it and maintain their current level of vision. … A lot of people don’t come in [for screenings] for fear of being diagnosed, and [that’s] obviously is not a good thing to do. By the time someone notices vision loss, the disease is very far advanced.”

According to the National Eye Institute, glaucoma is actually a group of diseases that damage the optic nerve in the eye. The most common type is called open-angle glaucoma, and it happens when the eye’s drainage canals become blocked, and over time, pressure builds behind the eye and damages the optic nerve.

Almost anyone can develop it, but African-Americans, Mexican-Americans and those who have diabetes or cardiovascular disease are among those at higher risk. People with family members who have glaucoma are highly likely to develop it, too.

“The biggest thing I tell my patients at the time of diagnosis is to make sure family members get screened,” said Meenakshi Chaku, an ophthalmologist with Loyola University Medical Center.

That’s because while glaucoma can’t be cured, it can be treated, and people can preserve their vision for longer periods of time. A healthy lifestyle will help, Chaku said, but there are no supplements or quick fixes for staving off the disease. It most often is treated with medication, but surgery can be an option, as well.

Kyle has tried medications, surgery and an experimental treatment that uses his own stem cells to try to regenerate cells in his optic nerve. He’s had mixed success, but tests so far are showing that the experimental treatment may have increased his vision, he said.

“I don’t want to give false hope,” he said. But he’s eager to see how technology and advances in medicine can help him and others who suffer from glaucoma, too.

And he urges others to not give up all hope.

“I had a couple of choices to make: I could continue not doing anything and not going anywhere, or I could find a way to cope with it.”

He chose to cope with it. Kyle said he sought support from family, friends and organizations for the blind. He learned how to take public transportation, for example, and how to use assistive technology for the blind. He now takes the bus and train from his home in Oak Park to Moody Bible Institute in Chicago, where he’s studying for a master’s degree in biblical studies.

“My life today is very manageable,” he said.

Erika Hobbs is a local freelance writer.