Of all the hardships Anna Mroz has faced in her 68 years—caring for a mother with epilepsy; fleeing communist Poland as a political refugee in 1985; adjusting to life in New York City without speaking English—none threatened her world as profoundly as the prospect of going blind.

Several surgeries had failed to repair a detached retina, leaving her blind in her right eye. Then, by last winter, the vision in her other eye had faded so much that Mroz found herself bumping into the walls of her apartment and people on the street. She saw shadows instead of faces.

Mroz feared losing her apartment and her independence, becoming a burden to her children, and not being able to see her newborn grandson. “I know what it’s like to see darkness out of an eye,” says Mroz. “To have that in the other eye, I just can’t imagine anything worse.”

Initially, an ophthalmologist near her home on Ocean Parkway in Brooklyn diagnosed her problem as a cataract. But when cataract surgery failed to make a lasting improvement, and then a retina specialist couldn’t help, she was referred in March 2015 to Mohammad Fouladvand, MD, a neuro-ophthalmologist at NYU Langone who specializes in treating neurological and systemic disorders that affect vision. From the abnormal shape and color of her optic nerve, Dr. Fouladvand suspected the problem was not in her eye, but her brain. He immediately ordered an MRI. “You have no time to lose with these cases,” he explains. “Once the vision is gone, it cannot be recovered.”

The scan bore out Dr. Fouladvand’s suspicions. Mroz had a benign schwannoma, a rare tumor that affects only a few thousand people in the US each year. The growth was compressing the optic nerve and would eventually cause Mroz to become totally blind. Dr. Fouladvand referred her to Chandra Sen, MD, director of the Division of Skull-Base Surgery in NYU Langone’s Department of Neurosurgery. A pioneering surgeon sought out for his expertise on skull-base tumors (he operates on 40 to 50 each year), he recommended immediate surgery to remove the tumor and preserve her existing vision.

But the stakes were high. Operations on deep-seated tumors like Mroz’s are considered high-risk because such masses are difficult to reach and often involve critical structures, such as the brain stem, cranial nerves, and blood vessels that feed important parts of the brain. Injuring any of these can result in stroke, paralysis, blindness, hearing loss, facial paralysis, loss of voice, or other problems. Mroz’s case was especially risky because she had vision in only one eye, and her optic nerve was in bad shape. “I could do the operation, and Ms. Mroz could wake up totally blind,” says Dr. Sen. “I told her that the most reasonable expectation would be to prevent further deterioration of her vision. If her vision were to get better, that would be a bonus.” To Mroz, any chance of seeing her grandson, then just two weeks old, seemed better than none. “Dr. Sen said, ‘I will do my best,’ ” she recalls, “ ‘but there is no guarantee this will help.’ I told him, ‘I can’t live like I’m living now.’”

Mroz underwent surgery on April 2 last year. Dr. Sen first removed pieces of Mroz’s skull and eye socket. Relying on a surgical microscope, skilled hands, and nearly 30 years of experience in the region where the brain and eye intersect, he moved cautiously amid a dense tangle of nerves, fat, and muscles. Dr. Sen took great care to avoid the nerves that control vision and eye and lid movement—all crucial for sight—as he painstakingly removed a tumor slightly larger than a hazelnut over the course of five hours.

When Mroz opened her eyes in the post anesthesia care unit, she could see clearly. In the weeks that followed, her vision improved so rapidly and completely that it surprised even Dr. Fouladvand, who rarely expects much from a damaged optic nerve. “Nobody thought she’d have more than partial vision,” he says.

Ultimately, however, Mroz’s field of vision expanded from 25 percent of its normal range to 100 percent, and her eyesight improved from 20/200 to 20/20. She no longer needs eyeglasses to read the morning paper. “I feel amazing,” she beams. Best of all, she says, she can see her grandson’s blue eyes.