How Does Diabetes Affect the Eye

Early Symptoms of Diabetic Eye Disease

Patients with diabetes are often unaware of any ocular involvement because they maintain good vision.  However, even when there are no pathologic clinical findings within the eye, diabetics can experience changes in their vision during episodes of high blood sugar levels.  When the blood sugar is elevated there is a change in metabolism within the lens as well as a change in osmolarity.  Together they result in a swelling of the lens which then compromises the eye’s ability to focus.  Generally the changes are moderate and vision returns to normal in 4 to 6 weeks, however if they are severe, it may take several months for the vision to recover, once the blood sugar has returned to a normal level.

Later Changes In The Eye From Diabetes

Clinical changes within the eye generally takes 10 to 15 years to manifest themselves, longer in those diabetics who are well controlled. When they do occur, vision may still be normal   because the center of vision, the macula, is spared.  There can be retinal hemorrhages and exudates, even abnormal vascular formations and new vessel growth, and the  diabetic can continue to experience good vision as long as the macular is still functioning well. As the macula becomes involved, it will begin to swell.  This results in not only decreased vision but a loss in ability to distinguish contrast in colors.   With the formation of abnormal vessels, there is a high risk of bleeding into the eye.  Depending upon the severity of the bleeding, symptoms will vary from a generalized haziness to large areas of darkness to just light perception.  Further, as is characteristic of its natural history, these abnormal vessels will proliferate then regress forming scar tissue wich leads to traction on the retina. This traction can then result in a detachment of the retina, including the macula.  The outcome is a significant decrease in vision, both central and peripheral.

What to Do For Diabetic Eye Disease

Because diabetic eye disease is generally slowly progressive and a consequence of poor diabetic control, it is important tightly control blood sugar levels in the normal range and to recognize the early eye symptoms, before vision is put at risk.  Early treatment has the best chance of not only slowing the progression of vision loss, but also reversing the diabetic changes.  Therefore, early recognition and treatment of diabetic eye disease will preserve eye sight and significantly improve long-term quality of life.


Mel Chen, MD

Retinal Specialist

Sarasota Retina Institute

Sarasota, Florida


  1. […]  Macular edema is defined as an abnormal macular thickening and excess fluid in the extracellular space of the retina. It is considered the leading cause of vision loss in the developed world in the working age population. […]

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