Background: Many people with diabetes have macular edema (swelling) at the back of the eye.
Macular edema can cause loss of vision. Studies suggest that inflammation may be involved in
the swelling. A drug called dextromethorphan may help prevent the inflammation and the
swelling. Dextromethorphan is approved for use as a cough medicine, but it has not been
studied to see if it can help in diabetic macular edema.
Objectives: To see if dextromethorphan can help treat diabetic macular edema.
Eligibility: Individuals at least 18 years of age who have diabetic macular edema in at least
one eye.
Design:
- This study lasts 2 years, and will require at least 14 visits to the National Eye
Institute outpatient clinic. Study visits will be every month for the first 2 months and
then every other month. Each visit will take about 2 to 4 hours.
- Participants will be screened with a physical exam, medical history, eye exam, and blood
tests. One eye with macular edema will be chosen as the study eye for testing.
- Participants will take dextromethorphan twice a day, about 12 hours apart, for 2 years.
A study diary will help keep track of the date, time, and number of pills taken.
- Participants will have study visits once a month for the first 2 months and then every
other month for the rest of the study. Each study visit will involve eye exams and blood
and urine tests.
- Four months after starting the study medication, participants may have laser surgery or
other treatments for the macular edema, if it is needed.