Diabetic retinopathy (DR) is the most common eye disease and the leading cause of blindness in U.S. adults, according to the National Eye Institute. Currently there are no proven therapies that slow the progression of DR, but according to a new study published in JAMA Ophthalmology, a low dose of doxycycline may do just that.

The research

Doxycycline is used to treat bacterial infections and is in the class of tetracycline antibiotics. This class of antibiotics has been shown to reduce inflammation, and the study looked at whether a low dose of doxycycline could potentially suppress the neuroinflammatory component of DR.

The 24-month trial included participants with either type 1 or type 2 diabetes who were affected by non-proliferative DR or non-high-risk proliferative DR. Participants were given a low daily dose of doxycycline for the period of the trial. Researchers measured:

  • Frequency doubling perimetry (FDP), a measure of inner retinal function

  • Contrast sensitivity

  • Visual acuity

  • Quality of life

  • Retinal thickening

  • Macular thickness

  • Retinal vessel diameters

The results

At the end of the trial, the participants treated with doxycycline had a significantly higher average of frequency doubling perimetry foveal sensitivity. Changes among the other measures were insignificant.

“To our knowledge, this is the first observation suggesting a link between a low-dose oral anti-inflammatory agent and subclinical improvement in inner retinal function. Oral doxycycline may be a promising therapeutic strategy targeting the inflammatory component of DR,” the study says. “Furthermore, study results suggest that FDP, which primarily measures inner retinal function, is responsive to intervention and may be a useful clinical trial end point for proof-of-concept studies in patients with DR.”

It’s not likely that doxycycline will be used in daily practice until further studies can confirm the results. The study's limitations included a small sample size of 30 patients. But researchers hope this research opens the door for larger trials to investigate the role of inflammation in DR.

To learn more on this topic:
Preventing Diabetic Retinopathy
Regular Exams Will Guard Against Retinopathy
7 Symptoms of Diabetic Retinopathy You Shouldn't Ignore