It was a sunny day when a healthy 39-year-old woman named Margrette was driving on a familiar road near her home. Temporarily “blinded” by the bright sun, she drove her car a few feet off the road and hit a utility pole. Fortunately, she was traveling only about 25 mph and was wearing her seat belt, and the air bags in her car worked. Even though she didn’t think she was injured, Margrette called an ambulance just to get “checked over” in the hospital.

The emergency technician filled me in on the details of the accident and explained that Margrette’s vital signs had been stable during the ride to the hospital. As I was about to begin her exam, I happened to notice that she had trouble reading a form she had been asked to sign. Everything checked out fine during Margrette’s exam, except for one unusual finding. When I used a penlight to peer into her eyes, I saw an obvious cataract in each of them. Wanting to confirm this discovery, I looked again—this time using a slit lamp (a type of microscope for the eye) and could see that the natural lens in both eyes had clouded dramatically—a surprising discovery in someone not yet 40. I then asked Margrette to read a handheld eye chart, and she had only 20/200 vision in each eye—generally considered a sign of severe visual impairment.  

Being blinded by bright light and having difficulty reading black print on white paper are common symptoms of cataracts, so Margrette’s momentary inability to see the road while driving into the sun and her trouble signing an unfamiliar form were beginning to make sense. If she had been driving at night, the oncoming headlights would most likely have affected her vision, too. Any sort of light can appear to a person with cataracts as though it has a bright “halo” around it—an extremely disconcerting sight.

As I probed further into Margrette’s background, even more pieces of her story fell into place. She confessed that she had not had her eyes examined since she was a teenager, even though she had begun having trouble reading around age 30. At first, drugstore reading glasses helped, but after just a few years, she found that reading glasses were useless. Frighteningly, she described her vision as “looking through a window smeared with cooking oil.” Her impairment went undetected, in part, because her state of residence does not require eye exams to renew driver’s licenses for people of her age. I was relieved when Margrette had cataract surgery shortly thereafter, and she was again reading 20/20 in time for her 40th birthday.

Why did Margrette get cataracts at such an early age? She explained that she had lived in Florida from birth until age 33 and hardly ever wore a wide-brimmed hat or sunglasses to protect her eyes. She also used oral and nasal steroids for asthma and environmental allergies. Excessive sun exposure and regular use of oral steroids have clearly been shown to cause premature cataracts. The evidence linking nasal steroids to cataracts is mixed, but Margrette said that she often used large doses, likely increasing her risk for this eye disease.

Lesson Learned: Subtle changes in vision can occur slowly over a period of several years. That’s why a professional eye exam every two years is critical to diagnose any eye disease early—before it becomes a serious problem. Cataracts are the world’s leading cause of blindness.