Can diabetes make you go blind?
The simple answer to this is yes, definitely.
The good news is this is rare nowadays and I will discuss why this is.
We should discuss how diabetes affects your eyes and in particular how it affects your retina.
Diabetes mellitus is a condition that leads to a rise in the sugar levels in your bloodstream. This can cause symptoms such as excessive thirst, excessive nocturnal urination and tiredness.
Over the longer term, high sugar levels in your blood stream can damage small blood vessels in your kidneys and eyes and damage nerves in your feet.
Diabetes can cause cataracts and damage to the retina. The retina is the layer coating the back of the eye. It picks up light signals and converts them to electrical signals. It then passes these signals to your brain for vision processing.
The retina is a delicate structure. It relies on high amounts of oxygen (via blood) to the eye.
High blood sugar levels can damage the small blood vessels of the retina. This can lead to a lack of blood supply to the retina.
This can also lead to leaking fluid in the central part of the retina called the macula. The macula is the area responsible for central vision and it is the area we use for most visual tasks.
If there is severe damage to the blood vessels of the retina, this may cause severe oxygen starvation. Then, new abnormal blood vessels can start to grow in the retina. Your vision at this stage may be completely normal.
If these grow undetected, they can bleed into the cavity of the eye (the vitreous). Patients will experience severe blurring of the vision. They might only be able to make out shapes rather than seeing any useful.
With time this blood within the vitreous can clot, shrink and cause scarring at the back of the eye. The vision becomes poor at this stage. Patients see movements in front of them but little detail.
With continued scarring, the retina starts to lift off the back of the eye. We call this a retinal detachment. At this stage, the retina cannot function well at all. Patients tend to see light coming into the eye but little else.
If this continues, many patients lose complete sight in that eye.
We call this scenario end stage proliferative diabetic retinopathy.
If you have leaking blood vessels in the macula, it can have a variable effect on your vision. We call this diabetic maculopathy.
If the leakage within the macula is mild, it will have little effect on your vision.
Generally the more fluid that accumulates within the macula, the worse the vision.
Oxygen starvation to the central macula can also occur. This leads to poor central vision. We call this diabetic macular ischaemia.
Patients with severe diabetic macular oedema or diabetic macular ischaemia do not tend to lose all their vision. They tend to keep some peripheral vision. Yet, some of these patients also tend to get proliferative diabetic retinopathy. If advanced, this can lead to total blindness.
Eyes can become blind and painful if abnormal new blood vessels grow at the front of the eye. This is a condition known as neovascular glaucoma. This condition is a result of severe oxygen starvation to the retina. Some unfortunate patients choose to have their eye removed if they cannot control the pain with drops or tablets. We can replace the natural eye with a prosthetic eye.
The good news is that we can prevent blindness from diabetes. We have a successful and ongoing screening programme in the UK. We’ve designed it to reduce the number of people going blind from diabetes.
If you have diabetes and live in the UK, the NHS will invite you to this screening programme. We’ll take photographs of the retina to detect early changes of diabetic retinopathy.
If we deem these sight threatening, we will refer you to a hospital so an ophthalmologist (an eye doctor) can examine your eyes. They’ll be able to assess the extent of the damage to your eye.
They will also tell you whether you need preventative treatment for proliferative diabetic maculopathy. They might also suggest treatment for diabetic macular oedema with intravitreal injections or laser.
With regular screening, check-ups and early treatment, diabetic retinopathy doesn’t always lead to blindness.
Patients that are at most risk are those who don’t attend their diabetic screening or hospital appointments. This may be because some patients think nothing is wrong with their eyes.
Some patients with advanced diabetic retinopathy have normal vision. So, I always urge people to get checked on a regular basis even if they have no symptoms. International patients often don’t have the benefit of a diabetic screening programme. I urge those patients to get checked on a regular basis.