Mini-Strokes May Cause Vision Loss

July 8 -- TUESDAY, July 7 (HealthDay News) -- A study of people who suffer the mini-strokes called silent cerebral infarcts could help explain the medical mystery of normal-tension glaucoma, Hong Kong ophthalmologists report.

Glaucoma is the progressive loss of vision caused by deterioration of the optic nerves, which carry signals from the eyes to the brain. It is customarily attributed to abnormally high pressure of the fluid in the eye. But glaucoma can occur in some people who have normal intraocular pressure, a phenomenon that puzzles eye doctors.

The Hong Kong study of 286 people with normal-tension glaucoma found a high incidence of silent cerebral infarcts among those whose loss of vision progressed more rapidly. The finding is in the July issue of Ophthalmology.

"We feel that our study does cast light on the pathogenesis of normal-tension glaucoma," said the study's lead author, Dr. Dexter Y.L. Leung, deputy coordinator of the glaucoma service at Hong Kong Eye Hospital. "We postulate that vascular [blood vessel] risk factors may be interacting with intraocular pressure in causing glaucoma optic neuropathy."

The study found that 29.6 percent of people with silent cerebral infarcts -- symptomless blockages of small brain arteries -- experienced steady deterioration of their vision, whereas such infarcts occurred in only 15.3 percent of those whose glaucoma-caused vision loss did not progress.

All study participants were Chinese, Leung noted. "We feel that a similar silent cerebral infarct-glaucoma relationship is likely to be applicable to other ethnic groups than the Chinese, but more studies are needed to confirm that," he said.

Doctors treating people with normal-tension glaucoma should consider obtaining brain images to determine whether silent infarcts have occurred, Leung said. There has been a debate about whether doing neuroimaging to detect abnormal growths within the brain is worthwhile, he said.