Berkeley - Small, barely detectable, changes
in the retina may predict the onset of vision loss in people
with diabetes and allow early treatment, if a study beginning
this summer at the University of California, Berkeley's School
of Optometry, is successful.
Preliminary tests have found a striking relationship between
these small changes and existing eye damage. Under the leadership
of optometry professor Anthony Adams, the school has now
launched a $1.6 million research project to study these
changes in people with diabetes.
Subjects are being recruited who have the disease but little
evidence yet of eye complications, said Adams, who will
complete in August a nine-year term as dean of the school.
Some 44 patients have already been enrolled; researchers
would like to enroll 100 or more adults under the age of
65 with good vision.
They will be followed for four years with the most advanced
techniques for measuring the health of the retina. Those
who develop eye problems will be referred for eye care that
could prevent severe vision loss.
Eye complications caused by diabetes are the leading cause
of blindness in the United States among adults ages 25-74.
The changes being studied are tiny alterations in the electrical
signals detected from patches of the retina, which contains
cells that transfer information from the eye's cones to
the brain. Declines in the size and speed of those tiny
signals correlate with eye complications in diabetics, said
Adams, whose research team first noted this in the retinas
of eight patients two years ago.
To the surprise of the researchers, they also discovered
tiny alternations in some patches of retina where no eye
complications were seen.
"We need to find out if these changes develop into a condition
called 'diabetic retinopathy'," said Adams. "We need enough
patients to know that our preliminary findings are not a
He said it is hoped the study will pinpoint those places
in the back of the eye that develop "retinal edema," leakage
of fluid into the retina, a leading cause of vision loss,
and "capillary dropout" where tiny blood vessels that supply
oxygen and nutrients to the eye collapse.
Laser treatment, if applied early enough, can slow the
progression of the disease. Good control of blood sugar
levels through medication, diet and exercise can significantly
slow or minimize it, said researcher Marilyn Schneck, a
principal investigator on the UC Berkeley study.
Even then, a significant number of diabetics may lose vision
despite their best efforts, said Schneck.
Subjects in the study are brought to a room in the optometry
school called "the Sugar Shack." There Schneck has studied
the relationship between sugar levels and eye responses
for the last 14 years. For this study she applies a technique
called the "multifocal electroretinogram" (M-ERG) that can
detect tiny electrical signals from specific areas of the
retina and display them in colorful computer graphics highlighting
the retinal changes.
Information on how
to participate in the diabetes study