Dangers of Diabetes to the Eye

Dr. Mukesh Aggarwal of the Eye Clinic & Laser Institute explains how diabetes can affect the eyes

Diabetes is a disease that affects more than 20 million people worldwide, and is the leading cause of blindness of people younger than 65. For many suffering from diabetes, this blindness is irreversible.

“Diabetes is a disease where the pancreas produces little or no insulin,” explains Mukesh Aggarwal, M.D. of the Eye Clinic & Laser Institute, which operates five offices on the Space Coast. “Insulin is an important hormone in that it controls the amount of glucose or sugar in the blood. This glucose or sugar is our body’s main source of fuel for the cells in the body.”

Dr. Aggarwal graduated from the Institute of Medical Science and then served an internship at Philadelphia Hospital. He completed three years of residency in ophthalmology at Albert Einstein College of Medicine in New York. He currently is a fellow of the American Academy of Ophthalmology, a fellow of the American Academy of Cosmetic Surgery and is a member of the American Society of Cataract and Refractive Surgery.


It is because every cell in the body uses glucose for fuel that having diabetes can be so devastating to the organs and tissues of the body if not kept under control. The disease can affect every single small and large blood vessel.

Diabetes is known to increase a person’s risk of heart disease, stroke, kidney failure and other circulatory system abnormalities, especially in the legs. It also may damage the nerves in the body causing problems with sensation.

The disease also can cause a wide range of problems that affect the eyes. Diabetes can cause reversible, temporary blurring of vision, or if uncontrolled, may cause severe and oftentimes permanent vision loss. Diabetes also is known to increase the risk of developing other eye conditions such as cataracts, macular degeneration and glaucoma.

“Diabetes can affect the eye in many different ways,” explains Dr. Aggarwal. “First and foremost, the unusual fluctuations in the blood glucose levels can affect the lens inside the eye, which may result in blurring of vision that may come and go throughout the day as the level of glucose in the blood goes up and down. Secondly, this fluctuation in the blood sugar can cause a cataract to grow at a quicker rate of speed, much sooner than it would for someone who has normal blood sugar. And last but not least, the most serious affect is on the network of blood vessels that supply the retina.”


Severe diabetic eye disease occurs in persons who have had diabetes for many years and have had little or poor control of blood sugars for an extended period of time. Dr. Aggarwal explains that uncontrolled blood glucose diminishes the vision in several ways. One may develop diabetic macular edema, which occurs when fluid leaks into the macula, the central part of the retina that allows people to see fine detail. When the fluid leaks into the macula it causes it to swell, which in turn thickens and elevates it.

Diabetic macular edema may develop at any stage of diabetic retinopathy, but most frequently occurs along with proliferative diabetic retinopathy. It may be treated with an intra-vitreal injection of a medication.

“Uncontrolled blood sugars can also cause proliferation or damage to all the small and large blood vessels in the body,” adds Dr. Aggarwal. “These blood vessels cannot adequately supply the retina with the nutrients and oxygen it needs, so in turn it grows new blood vessels.” These newly formed blood vessels are fragile and can leak blood into the jelly-like vitreous humor inside the eye and then into the retina itself, he adds, explaining that these hemorrhages can cause vision loss and permanent low vision. These new blood vessels are many times accompanied by scar tissue that can contract and tug on the retina and cause a retinal detachment.


In the non-proliferative or background diabetic retinopathy, the vision is not diminished in any way and there may be no symptoms. There may even be tiny weakened blood vessels that cause tiny bulges or micro-aneurysms. The more severe type, however, is proliferative diabetic retinopathy in which blood vessels are bleeding out into the vitreous and into the retina. This type can cause blurry vision, or even spots or areas of diminishing vision.

Generally, treatment for background diabetic retinopathy includes keeping control of blood sugar levels, keeping blood pressure within a normal target range, limiting blood cholesterol and exercising regularly. However, once the disease has progressed to proliferative diabetic retinopathy, it is important to have an appropriate course of treatment. Dr. Aggarwal says that in many instances the first course of treatment is laser therapy that only requires topical anesthetic. “This laser aims to cauterize the leaking blood vessels in hopes to stabilize the vision, not restore the vision that has already been lost,” he explains.

“When the abnormal blood vessel growth caused by diabetes begins to break or leak and cause a hemorrhage into the jelly-like vitreous, this decreases the vision by blocking the light from focusing on the retina,” says Dr. Aggarwal. When this happens, a patient may choose to have a vitrectomy, or have the vitreous suctioned out and replaced by a neutral saline solution to maintain the shape of the eyeball. Over time the body will replace the neutral saline with new vitreous.

New or abnormal blood vessel growth is caused by a vascular endothelial growth factor (VEGF). Another course of treatment is to give an intra-vitreal injection of a medication that is an anti-VEGF. This will in turn block the VEGF which will reduce the growth of the abnormal or new blood vessels and slow the leakage. It also helps to slow the loss of vision.

“Diabetes is a serious disease that should not be taken lightly,” warns Dr. Aggarwal, who explains that a person can have it for years and never even know it. That’s why it’s important to have a physical yearly and have a dilated eye exam yearly.

“It is important for one to keep the blood sugars under control and exercise and eat right,” says Dr. Aggarwal. “Once the diabetes has begun to affect the eyes, the course of treatment plays an important role in maintaining the person’s vision and preventing any loss or any further loss of vision.”

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