10 key points in the treatment of diabetic macular oedema
Macular oedema is the inflammation and accumulation of fluid in the macula, the part of the eye responsible for central and pinpoint vision
1. Good metabolic control
The basis of any treatment in diabetic patients is to exert control over the levels of glycosylated haemoglobin, blood pressure and hyperlipidaemia (cholesterol). This notably reduces the risk of not only systemic complications but also ocular ones.
2. Exercise and diet
Moderate exercise and a balanced, varied diet reduce the risk of complications in diabetic patients. As people used to say, “wear out your shoes and go easy on the stews.”.
3. Anti-angiogenic injections
The first line of ocular treatment for diabetic macular oedema (DMO) is the administration of intravitreal anti-angiogenic injections. These are drugs that reduce the concentration of a protein, vascular endothelial growth factor (VEGF), which is responsible for the increase in the permeability of retinal vessels and for fluid accumulation in the macula. In most cases, the treatment reduces DMO and improves visual acuity (1).
4. Effect on diabetic retinopathy
With anti-angiogenic treatment, almost a third of patients improve their diabetic retinopathy. Therefore, it not only controls DMO but also the base eye disease.
Given that inflammation plays a part in diabetic macular oedema, above all in the long-duration type, the administration of intravitreal corticosteroids can reduce the retinal increase over some months with a single injection (2). This is the second line of treatment, particularly in patients without glaucoma, who have undergone operations on cataracts that do not respond to anti-angiogenics and who have high cardiovascular risk.
6. Laser photocoagulation
This is the classic treatment for diabetic macular oedema. A thermal laser is applied to microaneurysms (small protuberances in the vessel wall from where the liquid causing the oedema is often filtered) in order to burn them. Currently, it is only used on patients with very specific characteristics, given that the outcome has been improved by anti-angiogenic drugs.
7. Micropulse laser
A micropulsed laser, despite using a laser source, does not produce any thermal effect by heating tissue, unlike the conventional thermal laser. This laser uses a coherent light emitted intermittently (3). It is extremely safe; in fact, following treatment it gives no indication that it has been used although its effect takes time to appear.
Indicated when the oedema is caused by adhesions between the vitreous and the macula, detaching it from its normal position. The technique of choice is pars plana vitrectomy (in which the membranes causing tractions are removed). Prior or subsequent use of injections is not contraindicated.
9. When should treatment start?
Once the oedema is causing vision loss and a significant increase in the macular. The outcomes are better when the treatment starts before irreversible damage occurs in the delicate structure of the retina.
10. For how long?
Diabetic macular oedema treatment needs to be aggressive in the first two years. Over time, the number of injections administered falls drastically and from the third year many patients have their diabetic macular oedema under control with either one injection or none.
1. Diabetic Retinopathy Clinical Research Network. Aflibercept, bevacizumab, or ranibizumab for diabetic macular edema- N Engl J Med 2015; 372: 1193-203.
2. Boyer DS et al. Three-year, randomized, sham-controlled trial of dexamethasone intravitreal implant in patients with diabetic macular edema. Ophthalmology 2014; 121: 1904-14.
3. Luttrull JK et al. Safety of transfoveal subthreshold diode micropulse laser for fovea-involving diabetic macular edema in eyes with good visual acuity. Retina 2014; 34: 2010-20.