A routine eye examination can show many things, from a minor change in a prescription or the need for a different contact lens solution, to a condition that may be life-changing or even life-threatening. One optometrist found this out first hand when he did what he does every day, an eye examination. But this was no ordinary examination. When he looked into his 48-year old patient’s eyes, he noticed that blood and other fluids were leaking out of the tiny blood vessels at the back of her eyes. He suspected that this was a sign of diabetes, referred her for further testing, and his suspicion was confirmed.

Why are our eyes so vulnerable? Small blood vessels and nerves are very sensitive to changes in blood sugar levels in the body. As sugar levels rise in the blood of someone with diabetes, nerves and blood vessels are damaged. While this happens everywhere in the body, it is not visible because skin and bones block our view. Our eyes, on the other hand, provide an unobstructed view where the damage done to the delicate blood vessels and nerves in the retina can easily be seen by an optometrist, who is often the first professional to notice these changes.

Diabetic eye disease comprises a group of eye conditions that affect people with diabetes. These conditions include diabetic retinopathy, diabetic macular edema (DME), cataract, and glaucoma, all of which have the potential to cause severe vision loss.

Diabetic Retinopathy

Over a prolonged period of time, high blood sugar levels from diabetes damage the tiny blood vessels in the retina, causing them to leak fluid or blood and distort vision.  Diabetic retinopathy may progress through four stages. In mild non-proliferative retinopathy, the earliest stage of the disease, small areas of swelling or micro-aneurysms may leak fluid onto the retina. As the disease progresses to moderate non-proliferative retinopathy the blood vessels may swell and distort, and begin to lose their ability to transport blood and essential nutrients to the retina. Severe non-proliferative retinopathy occurs as many more blood vessels are blocked, depriving areas of the retina of blood supply. These areas signal the retina to grow new blood vessels, leading to proliferative diabetic retinopathy as new blood vessels grow along the inside surface of the retina and into the vitreous gel, the fluid that fills the eye. These new blood vessels are fragile, making them more likely to leak, bleed or break. Resultant scar tissue can contract and cause retinal detachment, the pulling away of the retina from the back of the eye. If left untreated, this can lead to permanent vision loss.

Symptoms of Diabetic Retinopathy

In the early stages of diabetic retinopathy there are usually no symptoms. The disease progresses until it affects vision, at which stage it is often quite advanced. Changes in vision may be so gradual that they go unnoticed for some time. Blurred vision is often one of the first warning signs of diabetes. When other symptoms are present they may include floaters and flashes, poor night vision, sensitivity to light and glare, distortion of vision, and frequent changes in prescriptions for glasses. Some of these symptoms may indicate eye conditions other than diabetes, and need to be investigated. It is important to have a comprehensive eye examination if any changes in vision are noticed, and particularly if diabetes has been diagnosed.

Blurred vision may occur when insulin treatment for diabetes is started, but this should resolve once blood sugar levels stabilise.

“My vision changes along with my blood sugar levels. Some days I can see better than others.”  This comment by a person with diabetic retinopathy is typical of the nature of this eye condition.

Diagnosis of Diabetic Retinopathy

The optometrist will do a thorough eye examination, which includes visual acuity testing to assess clarity of vision at different distances and tonometry to measure pressure inside the eyes. The pupils may be dilated with eye drops, to allow the optometrist to examine the retina and optic nerve at the back of the eyes. He will check for changes to blood vessels, leaking blood vessels, and damage to the optic nerve which carries signals from the eye to the brain. If severe retinopathy is suspected, referral for further testing by an ophthalmologist may be necessary.

Treatment of Diabetic Retinopathy

The key to successful treatment is early detection! Although treatment cannot restore lost vision, it can slow the progression of the condition and prevent it from getting worse. Depending on the stage of the disease, treatment may include laser therapy to minimise leakage from blood vessels and reduce the proliferation of new blood vessels, or surgery to repair the most severe damage.

Control of blood sugar levels and maintaining a healthy lifestyle are fundamental to treatment, as expressed by someone with diabetes. “I learned that if I do everything I'm supposed to do, my vision seems to stabilise. My diabetes is now under control, and I'm able to use my magnifier, so I can see to test my sugar.”

Diabetic Macular Edema

Diabetic macular edema, a consequence of diabetic retinopathy, occurs when the macula, the central area of the retina, swells from the build-up of leaking fluid. The result is the loss of central vision. It is the most common cause of vision loss among people with diabetic retinopathy.

Symptoms of Diabetic Macular Edema

Initially, it may be asymptomatic, with symptoms being noticed only once the condition has progressed to the point that changes in vision occur. When symptoms are evident, they are similar to those of diabetic retinopathy, and may also include wavy vision and changes in the perception of colour.

Diagnosis of Macular Edema

A comprehensive dilated eye examination is essential. As well as assessing visual acuity, eye pressure, and examining the back of the eye for blood vessel and nerve changes, the optometrist will notice that areas of the retina reveal spaces filled with fluid.

Treatment of Diabetic Macular Edema

The therapies for treatment of macular edema may be used separately or in combination. Treatment options include anti-VEGF injections into the back of the eyes to block the protein which stimulates the growth of abnormal blood vessels, steroid injections into the eyes to reduce the leaking of fluid, and laser therapy to seal leaking blood vessels and reduce swelling. In advanced proliferative diabetic retinopathy, surgery may be performed to replace the gel-like fluid in the eye with a clear solution. Some of these therapies may require more than one administration over a period of time.


Although aging is the primary risk factor for the development of cataracts, people with diabetes tend to develop cataracts at a younger age and more rapidly than those without diabetes. With the clouding of the lens of the eye, symptoms may include blurry vision, double vision, sensitivity to light, halos around lights, faded colours, and frequent changes to the prescription for glasses or contact lenses.


Glaucoma is a group of diseases that damage the eye’s optic nerve due to elevated pressure within the eyes. While it can affect anyone, the risk for glaucoma is doubled for people with diabetes. People with diabetes may also have a less common form of glaucoma, neovascular glaucoma, which develops as a complication of severe diabetic retinopathy.  Symptoms of glaucoma include loss of peripheral vision or tunnel vision, halos around lights, reddening of the eyes, and eye pain.

ABC Reminder of Diabetic Eye Disease

ASYMPTOMATIC – there are usually no symptoms in the early stages of the disease. If you know you have diabetes, don’t wait for symptoms to appear.

BOOK AN APPOINTMENT – Visit your optometrist for a dilated eye examination when diabetes is diagnosed, and at least once a year thereafter, or as often as your optometrist recommends. Early detection is the key to minimising visual complications of diabetes.

CONTROL YOUR BLOOD SUGAR LEVELS – While diabetic eye disease can be treated, treatment goes hand in hand with management of blood sugar levels and maintaining a healthy lifestyle.

14th November 2017