Summary of Diabetic Eye Diseases
- Diabetic eye disease is a set of eye conditions that affect individuals with diabetes.
- Diabetic retinopathy is the most common cause of vision loss among individuals with diabetes, and a leading cause of blindness among working-age adults.
- It involves changes to retinal blood vessels, leading to bleeding or fluid leakage, and eventually distorting vision.
- Diabetic Macular Edema (DME) is a consequence of diabetic retinopathy that causes swelling in the centre of the retina.
- Effective management of diabetes through consistent medication adherence, physical activity, and a healthy diet can prevent or delay vision loss.
- Because diabetic retinopathy often goes unnoticed until vision loss occurs, individuals with diabetes should undergo a comprehensive dilated eye exam at least once a year.
- Early detection, timely treatment and appropriate follow-up care of diabetic eye disease can protect against vision loss.
- Diabetic retinopathy can be treated with several therapies, either used alone or in combination.
- Common diabetic eye diseases include diabetic retinopathy DME), cataract and glaucoma.
What Causes Diabetic Retinopathy?
Chronically high blood sugar from diabetes is associated with damage in the
tiny blood vessels in the retina, leading to diabetic retinopathy. The retina is
responsible for detecting light and transmitting signals through the optic nerve
to the brain. In diabetic retinopathy, blood vessels in the retina leaks fluid
or bleeds, distorting vision. In its most advanced stage, new abnormal blood
vessels grow on the surface of the retina, leading to scarring and cell loss in
the retina.
Diabetic Retinopathy May Progress Through Four Stages:
- Mild non-proliferative retinopathy. This initial stage involves small areas of balloon-like swelling in the retina's tiny blood vessels, known as microaneurysms. These microaneurysms may leak fluid into the retina.
- Moderate non-proliferative retinopathy. As the disease progresses, blood vessels that nourish the retina may swell and distort, leading to their impaired ability to transport blood. These changes contribute to the development of DME.
- Severe non-proliferative retinopathy. More blood vessels become blocked, depriving blood supply to areas of the retina. These areas secrete growth factors signalling the retina to generate new blood vessels.
What is Diabetic Macular Edema (DME)?
DME is the build-up of fluid (edema) in a region of the retina called
the macula, a crucial region of the retina responsible for sharp,
straight-ahead vision used in activities like reading, recognising faces and
driving. Among individuals with diabetic retinopathy, DME is the most prevalent
cause of vision loss, affecting approximately half of all people with diabetic
retinopathy. While DME is more likely to develop as diabetic retinopathy
advances, it can occur at any stage of the disease.
Who is at Risk for Diabetic Retinopathy?
Individuals with all types of diabetes (type 1, type 2 and gestational)
are at risk of diabetic retinopathy, with the likelihood increasing with the
duration of diabetes. Women who develop or experience diabetes during pregnancy
may face rapid onset or worsening of diabetic retinopathy.
Symptoms and Detection
What are the symptoms of diabetic retinopathy and DME?
The early stages of diabetic retinopathy usually do not present any symptoms. The disease often progresses unnoticed until it affects vision. Bleeding from abnormal retinal blood vessels can cause the appearance of "floating" spots, which may resolve on their own. However, without prompt treatment, bleeding often recurs, increasing the risk of permanent vision loss. If DME occurs, it can cause blurred vision.
How are Diabetic Retinopathy and DME Detected?
Diabetic retinopathy and DME are detected through a comprehensive
dilated eye exam, which includes:- Visual acuity testing: This test measures the ability to discern objects at varying distances using an eye chart.
- Tonometry: A procedure for measuring intraocular pressure.
- Pupil dilation: Eye drops are administered to enlarge the pupil, enabling an examination of the retina and optic nerve.
- Optical coherence tomography (OCT): Employing light waves (in contrast to ultrasound's sound waves), this method captures intricate images of internal tissues, including those of the eye.
During this examination, the doctor checks the retina for:
- Changes in blood vessels
- Signs of leaking blood vessels, such as fatty deposits
- Swelling of the macula, indicative of DME
- Changes in the lens
- Damage to nerve tissue
Should DME or severe diabetic retinopathy be suspected, a fluorescein
angiogram may be conducted. This involves the injection of a fluorescent dye is
injected into the bloodstream, typically via an arm vein. Images of the retinal
blood vessels are captured as the dye circulates to the eye.
Prevention and Treatment
Vision impairment from diabetic retinopathy can often be irreversible. However, early detection and treatment can reduce the risk of blindness by 95%. Diabetic retinopathy frequently presents no early symptoms, hence individuals with diabetes are advised to undergo a comprehensive dilated eye exam at least once a year. Those diagnosed with diabetic retinopathy may require more frequent examinations. Pregnant women with diabetes should have an exam as soon as possible, with additional assessments during pregnancy as necessary.
Managing diabetes effectively can delay the onset and progression of diabetic retinopathy. Studies also indicate that controlling high blood pressure and cholesterol levels can reduce the risk of vision loss among individuals affected by diabetes.
Treatment for diabetic retinopathy typically commences when the condition progresses to proliferative diabetic retinopathy (PDR), or when DME is present. patients with severe non-PDR, at high risk of evolving into PDR, might need eye exams every two to four months.
How is DME Treated?
DME treatment encompasses various therapies, either used independently or in combination:
Anti-Angiogenesis Injection Therapy
Anti-VEGF (vascular endothelial growth factor) medications, such as Avastin (bevacizumab), Lucentis (ranibizumab) and Eylea (aflibercept), are administered via injections into the vitreous gel. These drugs obstruct VEGF, a protein that can prompt the growth and fluid leakage of abnormal blood vessels.
Focal/grid macular laser surgery
This surgery involves creating small laser burns on leaking blood vessels near the centre of the macula. The procedure, typically completed in one session, helps to reduce fluid leakage and retinal swelling. Some patients might require additional treatments. The laser surgery may precede, coincide with, or follow anti-VEGF injections based on the patient's response to the therapy.
Corticosteroids
Corticosteroids, either injected or implanted into the eye, are sometimes utilised alone or in combination with other treatments. The Ozurdex (dexamethasone) implant releases a sustained dose of corticosteroids to suppress DME. However, corticosteroids increase the risk of cataract progression and glaucoma. Patients undergoing this treatment require regular monitoring for increased eye pressure and glaucoma development.
How is Proliferative Diabetic Retinopathy (PDR) Treated?
Historically, PDR has been treated using scatter laser therapy, or
panretinal photocoagulation. This involves creating 2000 to 3000 tiny laser
burns on peripheral retinal areas to shrink abnormal blood vessels. While often
completed in one session, multiple sessions may be necessary. This treatment can
preserve central vision but might affect peripheral, colour and night vision.
Scatter laser surgery is most effective before the onset of bleeding in new,
fragile blood vessels. Recent studies have shown the efficacy of anti-VEGF
treatments in managing not only DME but also PDR, making it an increasingly preferred
initial treatment option.
What is a Vitrectomy?
Vitrectomy involves surgically removing the vitreous gel from the centre of the eye, typically to address severe bleeding. Performed under local or general anaesthesia, the procedure uses ports for instrument insertion, like a vitrector, for suction and cutting. A saline solution replaces the removed vitreous to maintain eye pressure.
After treatment, the eye may be patched for a period, and it's common to experience redness and soreness. Eye drops have are prescribed to reduce inflammation and infection risk. If both eyes require vitrectomy, the second procedure is usually scheduled after the first eye has recovered.
What if Treatment Doesn’t Improve Vision?
If treatments don't improve vision, the eye doctor can assist in
locating low vision and rehabilitation services. They can also recommend
devices to optimise the use of remaining vision.