Diabetic retinopathy occurs when changes in blood glucose levels cause changes in retinal blood vessels.
Retinopathy is the most common form of diabetic eye disease and usually only affects people who’ve had diabetes for a long time. It can result in blindness. Retinopathy can affect type 1 and type 2 diabetics. The longer you’re diabetic the greater the risk of developing retinopathy and it becomes particularly dangerous if left untreated. A yearly dilated eye exam is recommended for all those diagnosed with diabetes to check for diabetic retinopathy.
Over time, prolonged elevated blood glucose levels damage the small blood vessels within the retina. This may cause bleeding and swelling of the retina. This can lead to a reduced oxygen supply to the retina, which can also cause the growth of abnormal blood vessels on the surface of the retina. These vessels will swell, leading to macular oedema (swelling), and leak fluid into the rear of the eye.
Over time diabetic retinopathy progresses and becomes a more serious issue, going from background retinopathy to causing significant vision problems and eventually blindness. This is why yearly eye tests are important, when you’ve been diagnosed with diabetes and if you notice any changes to your vision.
If any of the below conditions affect you, you should consider a dilated eye exam with your optician.
Risk factors include:
- Poor control of your blood glucose levels.
- Protein present in your urine (your GP will do a test for this)
- Elevated blood pressure
- Prolonged diabetes
- High cholesterol (triglycerides) in the blood
- Increased swellings (feet, legs, hands)
- Pregnancy (not gestational diabetes)
Long-term good blood glucose level management helps to reduce the risk of developing diabetic retinopathy.
There are three different types of diabetic retinopathy:
- Background retinopathy or simple retinopathy is tiny swellings within the walls of blood vessels. These are known as blebs and appear as small dots on the retina, usually accompanied by yellow patches. This is exudate, blood proteins leaking from the blood vessels. This condition needs to be monitored by an ophthalmologist. Background retinopathy has no treatment but patients will need regular eye examinations. Like many conditions of this nature, the early stages of diabetic retinopathy may occur without symptoms and without pain. An actual influence on the vision won’t occur until the disease has advanced to diabetic maculopathy.
- Diabetic maculopathy: The macula is a central area of the retina responsible for high definition vision, and this stage refers to the progression of background retinopathy into the macula. It’s characterised by oedema, hard exudates, micro aneurysms and ischaemia in the macular area. If the oedema is severe visual acuity will be reduced, a blue-yellow colour vision defect is usually noted before the loss of acuity. Management involves laser photocoagulation (tiny burns that destroy small areas of retina). This is usually painless and has no side effects, but can influence night driving and peripheral vision. This type of laser treatment for diabetic retinopathy won’t improve vision, but it can prevent deterioration.
- Proliferative retinopathy is an advanced stage of diabetic retinopathy in which the retina becomes blocked causing the growth of abnormal blood vessels. These can then bleed into the eyes, causing the retina to detach, and seriously damage vision. If left untreated, this can cause blindness. In the case of a vitreous haemorrhage, this loss of vision can be instant. Serious diabetes retinopathy cases may need eye surgery. This is usually diagnosed due to bleeding in the eye, late-stage proliferative retinopathy or ineffective laser treatment. This type of diabetic retinopathy eye surgery is called vitrectomy. Proliferative retinopathy is also treated with lasers, with a scattering over the whole retina. This destroys the starved area of the retina.
To reduce your risk you can take a few precautions:
- Take a dilated eye examination once a year. Your GP and Diabetic Nurse specialist will recommend this.
- Manage your diabetes strictly through medication, insulin, diet and exercise.
- Regularly check your cardiac health and risks, blood pressure and cholesterol levels.
- Test your blood glucose levels regularly. Notify your GP or Diabetic Nurse specialist if there are problems.
Glaucoma can affect those with diabetes and non-diabetics alike. It can be a complication of diabetes if retinopathy develops. Those who develop diabetic retinopathy have an increased risk of developing glaucoma.
Glaucoma is caused by an excess fluid pressing on the nerve at the back of the eye. This occurs when the small amount of fluid the eye produces in its middle chamber, which flows around the lens of the eye into the front chamber is unable to drain. The fluid should drain from the eye using a drainage network and will enter the bloodstream. If the drainage system becomes blocked, the fluid is trapped in the eye and this causes the pressure in the eye to build up and press on the nerve at the rear of the eye, leading to glaucoma. This nerve may become damaged in time. In a person with diabetic retinopathy, the growth of new blood vessels in the eye is thought to block the drainage of the fluid.
Glaucoma has very few symptoms in its early stage, so people may be unaware that something is wrong with them. As someone with diabetes, an optometrist or another eye specialist should test you for glaucoma at least once each year. This is usually done with regular eye tests.
Glaucoma may be diagnosed by an optometrist by measuring your eye pressure, checking the eye at the optic nerve, and testing the field of your vision. Experts will quickly be able to determine if you have glaucoma.
Glaucoma is treated using beta blocker eye drops including betaxalol, teoptic (cartelol), or timolol. If this isn’t effective, laser treatment is another option.
Laser treatment can be used to open up the blocked drainage tubes within your eye. This is called laser trabeculoplasty. An alternative to laser trabeculoplasty is cyclodiode laser treatment. This is done by destroying some of the tissue in the eye that produces the aqueous humour. It creates less fluid in the eye, which in turn reduces the intraocular pressure.
Laser treatments are usually quick and painless, although during the procedure you may feel a brief twinge of pain or heat. You may still need to use eye drops after having laser treatment.
Any damage to the eye caused by glaucoma cannot be repaired.