Diabetes causes blindness through a condition called diabetic retinopathy. Basically, diabetes interferes with the blood supply to the eye, which in turn damages a very important component of the eye called the retina. This results in reduced vision and possibly blindness.
The retina consists of tissue on the inner lining of the eye surface. This tissue is sensitive to light. The function of the retina can be compared to that of a film camera. The optics of the eye create a visual image on the retina of whatever the eye is looking at. This is how we see the world. The retina is also full of tiny blood vessels, which, if damaged, can cause vision problems.
The Retina And Diabetes
People with type 1 or type 2 diabetes may experience fluctuations in blood sugar and blood pressure levels. These fluctuations contribute to diabetic retinopathy, whereby the tiny blood vessels in the eye, called the capillaries, become weak and fragile and possibly break. The capillaries then loose fluid, which runs into another part of the eye called the macula. The macula is located close to the retina and controls precise vision. Some of the capillaries can even become completely sealed off, and this deprives the retina of the blood it needs to function properly. These events led to a deterioration in eye sight.
As diabetic retinopathy progresses, new capillaries begin growing in the eyes to try and compensate for the lack of blood getting to the retina. But these capillaries are also weak and break very easily. This causes bleeding in the eye, which leads to a major reduction in vision, and possibly blindness. In some cases, the retina actually separates from the wall of the eye.
Diabetes patients should go for regular eye examinations and report any changes in their vision to their doctor. Symptoms of oncoming diabetic blindness include:
Sudden loss of vision
Seeing dark spots in front of the eyes
Having trouble focusing when reading
Seeing rings around lights
Only advanced or severe cases of diabetic retinopathy require treatment. In the early stages of the condition, good management of blood sugar and blood pressure levels through correct diet, medication and exercise may be enough to keep the condition under control. It is not a foregone conclusion that a diabetes patient with diabetic retinopathy will eventually become blind, or even partially blind.
In more serious cases where further action is needed to prevent vision loss, one or several of the following treatments may be recommended:
Laser surgery - to stop fluid from leaking into the macular, and/or seal to the leaking blood vessels in the retina. This in turn prevents new, weak capillaries from growing to make up for a lack of retinal blood supply. If the retina has detached from the eye wall, it can be reattached through laser surgery.
Steroid injections into the eye - these injections can reduce fluid leaks into the retina. Steroid injections may need to be repeated at regular intervals or used in combination with laser surgery to achieve the desired result.
Cryotherapy - cryotherapy basically means freezing the blood vessels in the eye. This shrinks the abnormal capillaries that have developed in the eye, and helps the retina to reattach to the eye wall.
Likelihood Of Diabetic Eye Problems
Diabetes patients in the United States are reasonably likely to suffer from diabetic retinopathy, but this doesn't mean that they will eventually lose their sight. Approximately 40% of North American diabetes patients will develop some form of this eye condition, but many of them will prevent any worsening of the problem by managing their diabetes correctly. The longer a patient has diabetes, the more likely he is to develop eyesight problems. One study has found that 80% of patients who have had diabetes for 15 years suffer from diabetic retinopathy. Diabetics are also prone to other eye conditions such as glaucoma and cataracts.