Diabetes and your eyes

Did you know that the effects of diabetes are the leading cause of blindness in Canada?

Diabetes is the most common cause of new blindness in North America and current estimates say that two million Canadians have some form of diabetic retinopathy. With education and crucial eye care it is possible to reduce and prevent devastating vision loss. This article will help you understand how diabetes can affect the eye and your role in managing this important aspect of your health.

Diabetes is the name of a condition that results from the body’s inability to process the glucose (sugar) created by food. Lack of adequate insulin production, or poor response to insulin by the body’s cells results in high blood glucose, and if untreated with diet and lifestyle or medical intervention this can cause a host of serious health problems.

Diabetic retinopathy is the most severe of all diabetic eye conditions. High levels of glucose in the blood can compromise small blood vessels in the body and cause them to leak fluid and blood. Diabetic retinopathy occurs when the affected vessels are in the back area of the eye, called the retina.

The retina contains light detecting cells called rods and cones. It also is home to the macula, where all colour and detail vision is detected. The leaking blood and fluid make oxygen delivery less efficient and release chemicals in the blood which promote abnormal new vessel growth, and even more leaking.

The result: swelling, loss of vision and in the worse case, scarring that destroys the retina permanently. Catching diabetic retinopathy early is the key. Technologies such as digital retinal imaging can aid your eye doctor in tracking changes in the back of the eye in order to determine if interventions are working. Treatment for advanced stages of diabetic retinopathy include using a laser to seal leaking blood vessels or to minimize functioning parts of the retina so less oxygen is required. The best way to deal with diabetic retinopathy is by preventing it with careful blood glucose control.

Diabetics are also at high risk for developing early cataracts. Excessive blood glucose can impact the clear cells that make up the lens inside the eye that focuses the light onto the retina. A cataract forms when the clear lens becomes cloudy and opaque causing vision to become blurry and dull especially at night or in low lighting. Cataracts will eventually require surgery to remove the natural lens and replace it with an artificial one. It is important to note that wearing Sunglasses with 100% UV protection can help slow the onset of cataracts. If you are not sure if your sunglasses are providing appropriate UV protection, ask your optometrist to analyze and verify them for you.

Glaucoma is a disease that causes a gradual loss of peripheral or side vision over a number of years. This vision loss occurs because of damage or degeneration of the optic nerve, which connects the eye and brain. Optic nerve damage is the result of reduced blood supply, which is why we see increased risk of glaucoma in diabetics. Sudden onsets of glaucoma occur when the circulation and drainage system in the front half of the eye become clogged. Pressure builds dangerously as natural fluids, called aqueous humour, are unable to drain. The disruption to the aqueous circulation system and spike in pressure in the eye is a result of chemicals released from leaking vessels and causing new vessel growth.

The level of glucose or sugar in the blood is the most important aspect of diabetes to control. With uncontrolled high levels of blood glucose many tissues can take on fluid causing shape changes. In the eye, shape changes will cause a prescription change, making current glasses or contact lenses blurry. It is not uncommon for diabetics with poor blood glucose control to have fluctuating vision as the eye shape changes. This makes purchasing glasses or contacts more challenging as the prescription may not be the same from day to day.

Diabetes is a pervasive condition that impacts many aspects of your health. By keeping the blood glucose levels under control through medications, diet and exercise a diabetic can not only help their body health but they can stabilize their vision and prevent blindness. Most provincial health care plans recognize the risk diabetes plays in eye health and will cover most of the testing necessary to ensure proper diabetic eye care. Type 1 or 2 diabetics, with good control of blood glucose levels, should be seen by an optometrist or ophthalmologist every 6 months to 1 year. If there are signs of changes in the eye health more frequent visits may be necessary.

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