Glaucoma Diagnosis May Be Mistaken In Some Younger Chinese People

After following a cluster of 16 such patients for seven years and observing more than 100 others, the researchers have concluded that there's a new syndrome occurring in the Chinese population, and it may be less likely to lead to severe vision loss or blindness than typical glaucoma.

Glaucoma is a condition that occurs from accumulating damage to cells whose fibers make up the optic nerve, which transmits information from the eye to the brain. This disease is the second-leading cause of blindness worldwide, affecting one in 200 people over the age of 50, but is less common in younger people.

So when Kuldev Singh, MD, MPH, professor of ophthalmology, began seeing a number of young Chinese males 15 years ago who had been diagnosed with glaucoma, he became suspicious that perhaps they had another syndrome.

"I started to see a lot of Chinese men with advanced glaucoma at a young age," said Singh. "Many of them were terrified. Most were otherwise healthy and active and thus were surprised that they had this disease."

Singh noticed that not only were these patients young Chinese males, but almost all were nearsighted and many had normal eye pressure. Most glaucoma patients have high eye pressure, which is thought to lead to optic nerve damage. To see so many similar patients including many with normal pressure was unusual.

"It would be equivalent to someone having a heart attack when they have normal cholesterol," he said.

The combination of similarities among the patients led Singh to question whether these individuals, including some as young as 25, had glaucoma rather than another syndrome. So instead of the normal, aggressive course of treatment for young glaucoma patients - including surgery - Singh kept most of the patients on low doses of pressure-lowering eye drops as a precaution. As he suspected, none of the patients progressed toward blindness during the course of the study.

Singh began sharing his experience with doctors around the world and found he was not the only one with patients with these symptoms. Frequently, he said, a doctor in an online forum would describe a puzzling case of a young man with unexplained glaucoma. Singh would respond, "Is he nearsighted and is he Chinese?" and the doctor would respond, "How did you know?"

Singh said he thinks that optic nerve damage in these patients is caused by their nearsightedness, and that others have reported that nearsightedness is increasing in the Chinese population.

Nearsightedness is caused by a lengthening of the eye, and Singh and colleagues suggested in the paper that stretching the eye can damage the optic nerve. Since nearsightedness rarely gets worse in people after their 30s, the optic nerve damage may ultimately slow or stabilize in such patients.

"Some might say that by classic definitions, all of these patients have glaucoma," said Singh, because they meet the optic nerve damage criteria for the disease. But a second criterion for glaucoma is that it leads to progressive vision loss, especially if not adequately treated.

The cluster of patients did not appear to be headed for blindness over the seven years they were followed. But Singh calls the findings preliminary, and said further studies are needed. "If they don't appear to be progressing toward blindness right now," he said, "they shouldn't be treated as if they have a blinding condition, especially since surgery is associated with significant risks."

Singh hopes his paper acts as a warning to doctors to look closely at this population when diagnosing glaucoma, so they won't rush patients to surgery when it's not needed. "I would say tread gently with that population," he noted.

In addition to the cluster of young Chinese men mentioned in the paper, Singh has also observed this condition in Chinese women. To determine exactly how prevalent this condition is, Singh and colleagues are now surveying young individuals of Chinese ancestry in the Stanford community. While it is too early to make definitive conclusions regarding this study, the group has preliminarily found a surprisingly high prevalence of optic nerve damage. "Our suspicion is that this is an epidemic," he said. But only time will tell whether these individuals have glaucoma.

Singh hopes, eventually, to explain why this condition appears more often in people of Chinese ancestry relative to other populations, and whether there is a gender difference. For now, he wonders whether the syndrome is related to reports from other researchers of a recent surge in nearsightedness among the Chinese.

"The next step is to try to learn more about the natural history and genetics of this condition," said Singh, "and see whether there are subsets of the population more prone to it."

Co-authors on the study included Stanford ophthalmology residents Amish Doshi, MD, and Lorianna Lombardi, MD, as well as former Stanford residents Ken Kreidl, MD, and Douglas Sakamoto, MD. Results are published in the March issue of Ophthalmology.