Thirty years ago, the chances of going blind within five years of being diagnosed with severe diabetic retinopathy were no better than 50%. Today,early diagnosis, management and treatment of diabetic retinopathy gives a highly likely chance of saving sight.
How do you know?
The early (non-proliferative) stages of diabetic retinopathy usually have no symptoms and progressive damage occurs before any change to vision.
Once the disease reaches the proliferative stage, vision loss can occur rapidly and can be permanent.
This makes it essential for all those living with diabetes to have a comprehensive dilated eye examination at least every two years, or more often if recommended, and to follow professional advice to reduce the risks of diabetic retinopathy.
Once diagnosed with diabetic retinopathy, there is a need to be checked at least every 12 months, and possibly as often as 3-monthly, depending on the level of disease.
Regardless of whether or not a diagnosis of diabetic retinopathy has been made, it is important to visit an eye specialist or an optometrist as soon as possible if there are any sudden changes in vision.
The following symptoms may not necessarily be signs of diabetic retinopathy, but should always be checked:
dark spots or holes in the visual field
blurred, distorted, dim or double vision
difficulty seeing at night, or increased sensitivity to lights and glare
frequent changes in glasses prescription
bright haloes around lights
flashes and large “floaters” (floaters are specks in the form of dots, circles, lines or cobwebs that move across the field of vision. These will be most noticeable when looking at a white wall or clear sky).
The longer you have had diabetes, the higher the chance that you will get retinopathy. Even if your eye test results have always been clear, do not stop having regular eye checks.
An optometrist or eye specialist will use several tests when diagnosing diabetic retinopathy.
Visual acuity testing
The visual acuity chart measures sight at various distances. From a specified distance, the eye specialist or the optometrist will ask that progressivelysmaller rows of capital letters be read aloud.
Ophthalmoscopy and slit-lamp examination
Microscope-like viewing instruments will be used to view the retina for the following signs of diabetic retinopathy:
Leaking blood vessels with small haemorrhages on the retina
Swelling and inflammation (edema)
Fatty yellow deposits (exudates)
Fuzzy white ‘cotton-wool spots’ that indicate areas where tissue has died and become opaque
Before this examination, the eye care professional should dilate (enlarge) the pupils using eye drops. This gives a better view of the retina at the back of the eye but may cause vision to be blurry for a few hours. It is unwise to drive while the vision is blurry, so arrange how to get home before the appointment. In some patients a photograph of the retina may be taken without pupil dilation.
After the use of some anaesthetic drops, the eye care professional may use a tonometer to measure intraocular pressure which is the pressure of fluids inside the eye.
Additional testing may be undertaken, if appropriate, including:
Optical coherence tomography (OCT) scan: a non-invasive procedure that produces high-resolution images of cross-sections of the retina, allowing its thickness to be measured. This test can also show abnormal fluid build-up in and under the retina.
Fluorescein angiogram: for people with leaking blood vessels or macular edema, an eye specialist may perform a fluorescein angiogram. Fluorescein dye is injected into a vein in the arm and is taken up by vessels of the eye. This identifies any leaking vessels in the retina.