Small blood vessels throughout the body, including the eye, are affected by diabetes. The blood vessels can either be damaged or obstructed.
When ocular blood vessels are damaged, blood and fluid leak into the surrounding retina (i.e. retinal haemorrhage). Depending on the location and severity of the haemorrhage floaters may appear, vision may reduce dramatically or there may be no symptoms.
Blood vessel obstruction can lead to a number of complications. The area/s usually supplied by the blocked vessels undergoes reduced blood flow and if this occurs at the macular, central vision is affected. More issues can occur in response to blood vessel closure if it is widespread as oxygen supply to the retina is reduced overall. To compensate for this lack of oxygen the eye “grows” new blood vessels (called neovascularisation). The new vessels are fragile and leaky meaning they bleed into surrounding tissue. If this goes untreated a cascade of events occurs. Unchecked bleeding is followed by retinal scarring which can pull the retina away from the back of the eye, a “tractional retinal detachment”. Another complication can be growth of new fragile blood vessels in the drainage channels of the eye. This blocks fluid outflow from the eye leading to increased pressure in the eye. This process is called neovascular glaucoma.
· How long you have had diabetes
· How well the diabetes is controlled
· Systemic hypertension (high blood pressure)
· Systemic hyperlipidaemia (high cholesterol, triglycerides)
In decades past it wasn’t uncommon for people to go blind after a lifetime of having diabetes. Due to major advances in treatment and earlier diagnosis, visual prognosis is much better today.
Management and Treatment
Good diabetes control, maintaining normal blood pressure, keeping low blood cholesterol and triglyceride levels are extremely important measures to be taking to avoid sight threatening diabetic retinopathy (DR).
At an eye examination you can expect a number of tests to be performed including measurement of vision, prescription and intra-ocular pressure. Assessment of the anterior (front) of the eye as well as the retina will also be performed. To get a better view of the health of your eyes your optometrist / ophthalmologist will probably put drops in your eyes to dilate your pupils. Other tests including retinal photography, OCT (scan of layers in retina), fluorescein angiography (imaging of blood flow through retinal vessels) can be needed.
The aim of treatment can be to improve vision or stabilize disease progression and prevent further loss of vision. The three main methods of treating diabetic retinopathy (DR) are laser, intra-vitreal injection and surgery.
If your optometrist detects any significant diabetic retinopathy they will refer you to an ophthalmologist for further investigation and treatment, as required.
Regular eye exams are important – appropriate screening, follow up examinations and timely treatment can reduce the risk of severe vision loss or blindness by more than 90%. Ensure you always attend appointments with your optometrist or ophthalmologist in the recommended timeframe. If you ever experience a reduction in your vision or a sudden onset of floaters or spots in front of your vision see your ophthalmologist or optometrist immediately.