Diabetes and the Eye

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Diabetes is a disease that has grown and spread exponentially in the last 20 years, reaching epidemic proportions. Yet, many people do not know how devastating it can be and the effects it can have on the eye.

Background:

There are 2 main types of diabetes:

• Type 1 (Insulin dependent):
• Early onset (usually by teenage years)
• Autoimmune disease - the body attacks itself and causes destruction of the cells that make insulin
• Insulin is the chemical which promotes uptake of sugars from the blood into muscle and other tissues
• Treated with insulin replacement
• Can lead to death if not treated

• Type 2 (Non-insulin dependent):
• Later onset (usually over the age of 40)
• Body tissues develop resistance to insulin
• Very commonly associated with sedentary lifestyle, high fat diets, and obesity (No surprise its huge in North America!)
• Treatment:
• Early/mild: weight loss, diet changes, and exercise
• Moderate: All of the above plus oral meds that encourage glucose uptake
• Severe: All of the above plus insulin
• Significantly increases risk of heart attack, stroke, and kidney failure

The end result for both, if not well controlled, is high sugar (glucose) levels in the blood stream.

Normal blood sugar levels:

• Healthy patients should have glucose levels of approx 4 mM
• Diabetic patients are instructed to try to maintain them below 6 mM
• Uncontrolled diabetics often have glucose levels of 15-20 mM (if not higher)
  

The Eye:
While high sugar levels in the blood can affect the structure and function of cells and chemicals, the main concern in the eye is loss of integrity of the blood vessel walls.

The tiny retinal blood vessels can become leaky, thus allowing fluid, blood, and proteins to seep into the retina. If left uncontrolled, this can result in any combination of the following:

• Diabetic retinopathy:
• bleeding in the back of the eye, including leakage into the vitreous gel thus causing loss of vision
• lack of blood and oxygen delivery to areas of the retina
• death of retinal tissue - permanent loss of vision
• development of new, weaker blood vessels (neovascularization) which can cause further leaking and fibrosis of the retina
• Macular edema
  
• swelling of the macula (central part of retina) causing decrease of vision
• Retinal detachment:
• Fluid leakage behind the retina or fibrosis due to new blood vessels causing it to be pulled away
• Neovascular glaucoma:
• Due to the lack of oxygen delivery, new blood vessels begin to grow at the front of the eye and block the drainage of fluid causing increased pressure in the eye which can result in damage to the optic nerve - yet another way to cause vision loss
  

If the diabetes is adequately treated, some of the milder problems can be reversed and vision may be restored.

If you have diabetes, or know someone who does, it is very important to keep in mind the effect it can have on your eyes. Regular, annual eye exams are imperative and are no less than the standard of care of diabetic patients.

If there are any questions please feel free to ask. And as usual, please forward this information on to anyone who may find it useful.

Thanks for reading.