“We were kind of astounded by this—it’s a very unrecognized phenomenon,” said Richard Leigh, MD, assistant clinical investigator at the National Institute of Neurological Disorders and Stroke (NINDS). Dr. Leigh and his co-researchers had discovered that gadolinium, used in brain scans for stroke patients, sometimes leaks into eyes—literally highlighting abnormalities. The finding could lead to more accurate stroke treatment.
The researchers performed MRI scans on 167 stroke patients on admission to the hospital without administering gadolinium and compared those scans to scans taken using gadolinium 2 hours and 24 hours later.
They found that the gadolinium made some eyes glow brightly, marking the location of brain damage. It appeared that the stroke could compromise the blood-ocular barrier. “It looks like the stroke is influencing the eye, and so the eye is reflective of what is going on in the brain,” said Dr. Leigh.
In about three-fourths of patients, gadolinium leaked into the eyes on 1 of the scans: 66% in the 2-hour scan (typically leaking in the aqueous chamber, in the front of the eye) and 75% in the 24-hour scan (typically in in the vitreous chamber, in the back of the eye).
Older patients, those with hypertension and those with brighter spots on their brain scans (associated with brain aging) were more likely to show gadolinium in the vitreous chamber at 24 hours. In a minority of patients, both eye chambers showed gadolinium at 2 hours. In those patients, stroke tended to affect a larger portion of the brain and cause more damage to the blood-brain barrier than did strokes in patients with a slower pattern of gadolinium leakage or no leakage. The researchers observed the phenomenon in both untreated patients and in those who received tPA.
The findings raise the possibility that clinicians could administer a substance to patients that would collect in the eye, like gadolinium, and quickly yield information about the stroke without the need for an MRI, the researchers say. “It’s much easier for us to look inside somebody’s eye than to look into somebody’s brain,” Dr. Leigh said. “So if the eye truly is a window to the brain, we can use one to learn about the other.”