Diabetic eye disease

How does diabetes affect the eye?

Over time, diabetes can affect the integrity of small blood vessels in various parts of the body – but especially in the eye, the kidney, and in the peripheral nervous system.

In the eye, diabetes can cause any one or more of the following:

leakage of fluid at the macula (the part of the retina responsible for your central vision)
deposition of proteins and lipids in the retina (known as exudates)
loss of blood supply to the macula
retinal haemorrhages
retinal nerve fibre layer infarcts (“cotton wool spots”)
growth of abnormal blood vessels
vitreous haemorrhage
secondary (rubeotic) glaucoma
cataract

These images show the are the right and left retina of a patient with diabetic retinopathy. There are retinal haemorrhages (red patches), exudate deposition (yellow patches) and in the right eye there is growth of new blood vessels together with previous laser treatment scars.

Any of these conditions can lead to loss of vision – until recently, diabetes mellitus was the leading cause of blind registrations in the UK in adults under the age of 65 years.

All patients with diabetes need to have periodic retinal examinations, and the frequency of follow-up required will depend on the findings at initial examination.

What tests are available for diabetic retinopathy?

Colour fundus photography (see above) is helpful for documenting the state of the retina at any point in time. OCT scanning is helpful for diagnosing and monitoring macular swelling in diabetes. Fluorescein angiography (FFA) is helpful for delineating areas of loss of blood supply, assessing suitability for macular laser treatment, and looking for new abnormal blood vessels.

This is an early frame from a FFA test in a patient with diabetes. It demonstrates several abnormalities that can help guide diagnosis and treatment, including small bright white spots (microaneurysms), an enlarged and irregular dark zone in the middle of the macula (foveal avascular zone), and a bright area to the left demonstrating leaking dye (new abnormal blood vessel growth).

What treatment is available for diabetic eye disease?

New (abnormal) blood vessels growing on the retina (retinal neovascularisation) is usually treated with panretinal laser. This treatment causes regression of the abnormal vessels, reducing the chance that they will break and cause vitreous haemorrhage.

This is a montage colour image of an eye with diabetic retinopathy which Mr Shah has freshly treated with panretinal photocoagulation (PRP) laser. The laser treatments are visible as light grey spots.

Diabetic macular oedema can be treated with any of the following three modalities:

macular laser
intravitreal injections of anti-VEGF
intravitreal steroid implant

Each option has its own advantages and disadvantages and sometimes a combination of more than one treatment is chosen. This is a constantly evolving area and retinal specialists are often modifying their approach to managing this condition every several months, based on the latest data from large clinical trials.

Mr Anish Shah FRCOphth

Diabetic eye disease

One thought on “Diabetic eye disease”