Diabetic Retinopathy

• Macular Oedema – swelling of the retinal tissues at the central part of the retina (macula) due to leakage of damaged small blood vessels (capillaries). If the very centre of the macula involved this can result in a reduction in central vision.
• Macular Ischaemia – loss of capillaries at the macula can lead to irreversible central visual deterioration.
• Proliferative Diabetic Retinopathy – as capillaries are lost, the retina progressively becomes ischaemic (lacking adequate blood supply). This can lead to the stimulation of new blood vessel growth which unfortunately does not restore the normal blood supply but rather leads to the growth of small fragile blood vessels on the surface of the retina. These new vessels can bleed into the vitreous gel in the centre of the eye (“vitreous haemorrhage”) leading to loss of vision. The new vessels can also lay down scar tissue which can contract and cause permanent visual loss due to tractional retinal detachment if not treated with surgery.

Patients with both Type 1 and Type 2 diabetes mellitus are at risk of developing diabetic retinopathy. The longer a person has diabetes and the poorer the blood sugar control over this time, the higher their risk of retinopathy. Other risk factors include poor control of blood pressure (hypertension) and blood lipids (cholesterol and triglycerides).

To reduce the risk of developing diabetic retinopathy a close relationship with your GP or endocrinologist is recommended with the aim of tight glycemic (blood sugar) control as well as good control of blood pressure and blood lipids. Regular exercise is important in all patients and weight loss is particularly beneficial in patients with Type 2 diabetes.

In the early stages of the disease there are usually no symptoms. For this reason, regular eye examinations are required to detect the development of these changes. As the severity of retinopathy progresses it may become apparent to the patient by way of blurred vision or floaters.

Diabetic retinopathy is detected by a comprehensive dilated retinal examination in conjunction with Optical Coherence Tomography (OCT) scanning of the macula. Changes over time can be documented by retinal photography. Fluorescein angiography is a dye test used to directly visualize the degree of damage to the retinal blood vessels and is often used in the management of diabetic retinopathy.

• Macular Oedema – Treatment may be required for cases where swelling of the retina involves the centre of the macula or is threatening the centre of the macula. Milder cases may be observed. Intravitreal anti-VEGF injection therapy with drugs including Lucentis (ranibizumab), Eylea (aflbercept), and Vabysmo (faricimab) is the mainstay of therapy. In some cases steroid injections such as Triescence (triamcinolone) or Ozurdex (dexamethasone) may be also be required. Focal laser therapy may be appropriate in select cases with leakage originating well away from the centre of the macula.
• Macular Ischaemia – No treatment is possible.
• Proliferative Diabetic Retinopathy – The aim of treatment is to cause shrinkage (regression) of the abnormal new blood vessels. This reduces the risk of vitreous haemorrhages which are often slow to clear, and prevents the development of severe vision loss that can result from scar tissue on the retina. The main treatment modalities are:
  Panretinal Photocoagulation (PRP) Laser treatment – laser treatment is applied to the peripheral retina that has suffered significant loss of capillaries and perfusion (blood supply).
  Intravitreal anti-VEGF injection therapy – works rapidly to shrink abnormal new vessels.
  Vitrectomy surgery in advanced cases to clear a vitreous hemorrhage or treat retinal scar tissue.

Untreated diabetic retinopathy can result in permanent vision loss. Regular eye examinations will reduce the risk of vision loss by detecting signs of early diabetic retinopathy whilst at a treatable stage.