Sen. Rand Paul (R-Ky.) is planning to visit Guatemala to treat patients with eye and vision problems during Congress’s break in August. (Drew Angerer/European Pressphoto Agency)

Sen. Rand Paul (R-Ky.) has spent considerable time in recent years cultivating supporters and donors and serving as a partisan counterweight to President Obama’s top priorities.

Just three years into his first term in the Senate, Paul has talked openly about running for president in 2016, giving speeches at GOP party conventions in Texas, Iowa and Idaho, attending a reunion of top supporters of 2012 GOP presidential candidate Mitt Romney and sitting alongside influential conservative media mogul Rupert Murdoch at the Kentucky Derby.

But Paul is planning a summer trip that appears more focused on his past than on his future, one that bypasses Iowa, New Hampshire and the other key nomination states.

When Congress adjourns for a five-week recess in August, Paul plans to join a medical mission to Guatemala, where he will team up with eye surgeons, nurses and technicians from the University of Utah to visit Salamá, a small manufacturing and commercial center nestled between two mountain ranges 3,000 feet above sea level, north of Guatemala City.

The trip doesn’t play into his political future “in any conscious fashion,” Paul says. But for a presidential hopeful everything matters. The mid-August trip, for example, is also likely to include a small band of aides and reporters. What other potential presidential candidates can say that they have helped the blind see?

Long before he entered politics, Paul attended the Duke University School of Medicine and became an ophthalmologist. He spent 17 years practicing medicine in Bowling Green, Ky., before running for the Senate in 2010. As a senator, he frequently performs pro-bono surgeries in Kentucky.

Paul and the surgeons plan to treat dozens of patients who are blind or suffering from other vision problems.

“I’ve been doing this for a long time. It’s what my first passion has been — medicine and surgery — and I figured I spent a long time learning how to do it, and I wanted to give back something,” Paul said in a recent interview.

During the trip, Paul plans to reunite with Juan and Andres Hernandez, two men he met 20 years ago. Some of Paul’s close friends brought the then-blind boys from Guatemala to Kentucky in hopes that he could help correct their vision.

“We were never quite certain how much vision they’d get back. But we figured they would get it back because they have nystagmus,” an involuntary and repetitive movement of the eyes, he said. “They were able to get useful vision, or ambulatory vision back. We were excited for them, and we’re excited to see how they’re doing and whether they need anything else.”

The Hernandez brothers were not available for comment. But Judy Schwank and her husband, Bill, who brought the brothers to Kentucky to be treated by Paul, recently reconnected with them in Guatemala and said that they have agreed to the August reunion.

“They still call him Dr. Pablo,” she said.

Paul grew notably animated as he discussed the details of ophthalmology and the types of vision problems that afflict an estimated 39 million people in developing countries.

“I don’t get to talk shop too much anymore,” he admitted. “I’ll do some at home, a couple of times each year. I did some [pro-bono surgeries] in Paducah [Ky.]. I enjoy being back at it.”

Paul will receive no compensation for his work, and he has asked friends and donors to donate about $20,000 to help the University of Utah’s John A. Moran Eye Center pay for the costs of the trip, including the transportation of advanced microscopes and other equipment into the Guatemalan mountains.

“It’s a great opportunity for us to bring awareness of the trouble of blindness worldwide,” said Michael Yei, manager of the Moran Eye Center’s outreach division.

During the past 18 years, the center has dispatched 20 physicians and dozens of nurses and specialists to more than 20 countries in the developing world to perform eye surgeries and train local ophthalmologists. The doctors establish years-long projects and return frequently to perform surgeries and train local ophthalmology students.

The trip requires a complex set of logistical and security arrangements. Paul’s staff has been preparing for weeks in consultation with Julio Ligorria, the Guatemalan ambassador to the United States.

“For us ambassadors, it’s very important to have a good relationship with the House and Senate,” Ligorria said in a recent interview. When he learned of Paul’s plans to visit, “I realized it would be important to not only be grateful, but also to support him, because our rural residents have all sorts of needs. And when any American medical mission comes, the least we can do is be grateful and help them however we can.”

While in Guatemala, Paul said he hopes to learn more about what the government is doing to help stem the recent exodus of young children and families who are fleeing into Mexico in hopes of crossing into the United States.

“We can’t have an entire exodus of countries coming. We’re a big country, and we accept a lot of people, and I’m open to a lot of people coming into our country, but it has to be orderly,” he said. “There’s a danger that some of these kids are going to die coming up here and in the deserts. So we need to have something more humane, and we could probably get some more of their help on their end, too.”

Paul will be in Guatemala for about a week. Once he returns, his summer recess schedule includes “considerable time” back home in Kentucky, a spokesman said — and then “a quick trip to Iowa.”