Craig Blackwell, MD
Ophthalmology

Santa Cruz, CA
Diplomate: American Board of Ophthalmology
Fellow: American Academy of Ophthalmology

Welcome to the Website of Craig Blackwell, MD

An Ophthalmology Practice in Santa Cruz, CA

Diabetic Retinopathy

Diabetic Retinopathy

In addition to the text here there is a video presentation at the following link:

Video: Diabetes and the Eye

Diabetes is a disease in which abnormally high blood sugar content damages blood vessels throughout the body. Specifically, damage occurs to the fine capillary vessels that deliver oxygen and nutrients to the tissues and pick up waste products. The retina is a privileged location where we can directly observe the health of the capillary vessels, both to monitor the status of the retina, and to get an idea of the circulation to other organs, like the heart, kidneys and brain.

Diabetic Retinopathy. Mild.
The white arrow is pointing at a ring of “exudates.” The yellow spots are the lipid part of the leaking serum and mark the edge of an area of edema.
The black arrow is pointing at a small hemorrhage.


Diabetic Retinopathy. Moderate severity.
Compared to the first photo note the increased number and density of exudates and hemorrhages.

The first stage of damage from diabetes is the vessels become leaky. The clear serum part of the blood leaks into the retina. Excess free fluid in tissue where it doesn’t belong is called edema. If there is edema in the center part of the retina it will reduce vision. If it is there for a significant period of time it will scramble the finely organized structure of the retina and even if the edema eventually clears it will leave permanently reduced vision. If edema is detected in a timely fashion the leaking area can be identified and cauterized with a laser or cleared by other methods.

The second stage of damage is when the vessels close down and no longer supply blood to the retina. Besides reducing function, in this situation the retina that has impaired blood supply sends out a chemical messenger that stimulates the growth of new blood vessels (Vascular Endothelial Growth Factor, VEGF). In principle, that sounds like a good idea, but in practice it turns out badly. The new vessels are fragile, and have a strong tendency to bleed and bring scar tissue into the eye. This is the more ominous stage. Treatment becomes more involved and difficult and the success rate drops significantly.

Keys to success:

  • Maintain the best, most consistent, control possible over blood sugar and blood pressure.
  • Have regular retina checks. If there are complications they are much more successfully treated if caught early.