Over the past year, Muanema Fakira noticed something odd about the eyes of her 1-year-old daughter Sumaya. Her left eye was cloudy. It did not gleam with curiosity or glint in the sun. When the problem persisted, Ms. Fakira made the rounds to health clinics in their town in central Mozambique. Doctors said they could not help.

But they knew of someone who could, if Ms. Fakira could take Sumaya, now 2, on a 100-mile journey to the coast.

The family made the trip to the city of Quelimane, where Dr. Isaac Vasco da Gama examined Sumaya’s eyes and quickly diagnosed a congenital cataract.

Ms. Fakira was skeptical — cataracts are for old people, she said. But Dr. da Gama explained that an infection at birth, or shortly after, can cause cataracts in children. The condition is particularly worrying because vision problems affect the development of a child’s physical function. But the good news, he said, was that the problem can be solved with a simple surgery, one he does a dozen times a week at Quelimane Central Hospital.

This was particularly lucky for Sumaya because Dr. da Gama is one of just three pediatric ophthalmologists in Mozambique, a country of 30 million people.

Sumaya had her surgery in November, and a day later headed home, already recovering. Dr. da Gama was pleased to have seen her while she was still young, before permanent damage was done.

It was a sign that a system he and colleagues have been trying to put in place for the last few years might be taking hold: Sumaya’s parents sought help from the medical system for an eye problem — rather than a traditional healer, or a sorcerer to remove a curse.

When Sumaya was referred for care, it was a long and expensive trip, but she got help relatively quickly for a problem that might otherwise have blighted her life. Ideally her cataract would have been spotted at birth by a midwife.

“I do believe that by pushing forward, we can slowly overcome this challenge,” Dr. da Gama said.

In Mozambique, as in much of sub-Saharan Africa, awareness of vision problems is so low, and access to help so limited, that few children get the care they need, even though many suffer from easily treatable problems.

In 2021, a global commission on eye health reported that 510 million people around the world, 90 percent of them in low- and middle-income countries, had uncorrected vision impairment. That is, they could not see properly because they did not have glasses.

The consequences are enormous: Children with vision loss in these countries are significantly less likely to be in school. One study found that for those who do attend school, those with uncorrected vision problems learn half as much as their peers with normal vision.

Access to treatment is so limited because of a scarcity of trained staff and a failure to integrate vision care into health systems. Children are not screened for vision loss, and parents and teachers don’t understand the simple causes of eye trouble that can manifest in distraction, lack of physical coordination and behavior issues.

Mozambique has just 20 ophthalmologists, up from six two decades ago. Almost all of them are based in the capital, Maputo, in the south.

Dr. da Gama completed his studies in India in 2017 and set up a clinic in Quelimane, a seaport town halfway up Mozambique’s long Indian Ocean coastline. But to his surprise, he saw very few patients in the first year. He discovered that no one was being referred to him because health workers did not recognize treatable eye diseases. He started traveling to local clinics to tell medical workers about screening and solutions.

Then he teamed up with the charity Light for the World, which had sponsored him to complete specialized training in pediatric eye care in Tanzania. They designed an outreach program to show teachers, community health workers, traditional healers and local leaders how to spot vision problems and to refer children to the new ophthalmology ward at the Quelimane hospital.

Now, a couple of times a year, for up to a month at a time, he takes a mobile clinic to small communities to do surgeries on children with cataracts, glaucoma or strabismus (misaligned eyes).

Cataracts cause nearly half the preventable blindness in Mozambique’s children; they can be genetic, or the result of trauma (like a stick or a stone in the eye), or of an untreated eye infection.

On his outreach journeys, Dr. da Gama teaches other health care workers how to perform the simple surgeries, and how to spot the conditions. “Operating per se is not a problem: We can train in a week, two weeks, how to operate on a cataract,” he said. “But it is how to identify the children who need the operations.”

Mozambique’s Ministry of Health is trying to build awareness of vision problems and refractive errors, for which a pair of glasses is a life-altering intervention.

Glasses or simple surgeries that keep children in school can change the future for their families, and for the country as a whole. “If you have children less educated or with fewer skills,” he said, “the future of the economy is affected.”

In Quelimane, Dr. da Gama also sees cases of retinoblastoma, a cancer of the retina. When patients come early enough, he can save their lives, if not their eyes.

Camilo Rosario brought his daughter Grace, 3, to his clinic in November, from their home in a village 300 kilometers (about 185 miles) away. She had a tumor protruding from her eye that caused her excruciating pain. Mr. Rosario said she had begun to complain about her eye just weeks before. He shifted anxiously from foot to foot while Dr. da Gama explained that he would operate quickly to remove the tumor, but that he feared the disease was already in her brain.

Grace soon recovered from the first surgery, clinging to her father with a bulky bandage around her head. But as Dr. da Gama had feared, she had come to him too late; she died in early January.

Aminata Kaba was screened alongside her classmates in high school last year — and was surprised to learn that she was myopic. After she got glasses, school became significantly easier, she said, and her grades soon improved. Now, she said, she will continue on in school, and she hopes to be a lawyer.

Screening older children is easy; coaxing cooperation out of the small ones is a much greater challenge, Dr. da Gama said. They rarely look where he needs them to for eye exams. The eyedrops, the equipment, even his white coat, all can be frightening. He said he smiles and sings to distract, removing the coat when required.

“I like difficult things,” he said.