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This disease develops slowly, so we often don’t notice in time that something is wrong with our eyesight. And DME is the leading cause of reduced visual acuity in patients with diabetes.
Joanna Lewandowska, editor-in-chief of Warsaw Press: Doctor, what is diabetic macular edema (DME) and what symptoms accompany it?
Prof. dr hab. Sławomir Teper, President of the Polish Diabetes SocietyDiabetic macular edema (DME) is the leading cause of markedly reduced visual acuity in diabetic patients. The disease progresses slowly and the patient often does not notice that the vision initially deteriorates slightly, while the amount of exudate gradually builds up in the central retina (macula). Macular swelling can be spongy, where the spot becomes uniformly thick, or cystoid, where fluid-filled cysts form. As a result of increasing edema, the retinal tissue undergoes remodeling and degeneration, which is functionally manifested by further deterioration of visual acuity, sometimes to the level of functional blindness. Due to the fact that the central part of the retina is affected by the disease, patients have the greatest problem with near vision, and thus with everyday functioning – they lose the ability to read, check the time on the watch, make tea, use basic devices, etc. Advanced diabetic macular edema gives symptoms similar to a disease that remains the leading cause of blindness in Poland – the neovascular form of age-related macular degeneration (AMD) and results in an equally strong deterioration of the quality of life.
What are the disease statistics?
In younger people, DME predates AMD as the leading cause of functional blindness. Diabetes mellitus and its complications are a growing epidemic. This also applies to diabetic macular edema. Although precise epidemiological data are not available in Poland, they can be estimated. In the countries of our region, from> 4% (Lithuania) to even 12% (Bosnia and Herzegovina) of the population suffers from diabetes. Across Europe, it is almost 60 million people. Over the course of life, 1/3 of people with diabetes will develop diabetic retinopathy. In contrast, 1/3 of people with diabetic retinopathy will develop macular edema. It is worth noting that the primary risk factor is simply the duration of diabetes. Before the introduction of insulin therapy, diabetic retinopathy was not observed – patients did not live with the disease long enough to cause changes in the retina. Although proper diabetes care delays the development of retinopathy (keeping the percentage of glycosylated hemoglobin below 7% chronically), many people cannot avoid it. Over a two-year period without treatment, 50% of DME patients lose two lines on ophthalmic charts. The rate of progression is slower than with neovascular AMD, but due to the progressive nature of retinopathy, visual acuity may eventually be lower and even be associated with complete blindness in some patients.
How is diabetic macular edema (DME) diagnosed and why is this diagnosis crucial for the patient’s therapeutic process?
Many countries have an ophthalmic screening system for diabetic patients. This is due to the economic calculation – quick implementation of treatment is cheaper and more effective, and patients remain fit. A situation should not be allowed when the swelling is so intense that the treatment does not bring the expected results due to the destruction of the macular structure. Often the disease does not progress the same in both eyes. A person with diabetes does not notice any deterioration because they are looking with both eyes. Meanwhile, diabetes often affects young, working people who have many years of life ahead of them. The consequence of untreated treatment is the final cessation of professional work and often the necessity to use the care of third parties, so also for social and economic reasons, this group of patients should be especially taken care of.
The basic diagnostic method is fundus examination by an ophthalmologist, which should be supplemented, if necessary, with additional examinations. Accurate determination of the thickness of the retina and the presence of even a minimal swelling is possible thanks to the use of optical coherence tomography (OCT) – a non-invasive method that includes allows to obtain sections of the retina. If peripheral retinal ischemia is suspected, wide-angle fluorescein angiography can also be performed.
What are the treatment options for patients with DME?
Over the past decade, there has been a revolution in the treatment of DME. Inhibitors of vascular endothelial growth factor (VEGF), a cytokine responsible for many disease processes, when it is secreted in excess, have appeared on the market. Increased VEGF concentration is noted in both neovascular AMD and DME, as well as in several other ophthalmic diseases. VEGF inhibitors have become the first-line drugs in DME, gradually replacing the previous gold standard of macular laser therapy. Using this method, in a focal or scattered way, we direct the laser beam into the macula and make successive pulses, the energy of which is concentrated in the area of the pigment epithelium, affecting the local metabolism of the retina. The intention of the ophthalmologist is then to keep the macular center in the best condition and to limit the secretion of VEGF.
What is anti-VEGF treatment?
Currently, VEGF inhibitors are administered by injection into the eyeball. The treatment regimens differ slightly depending on the selected preparation, but the principle is the same – the injections, initially administered monthly, are designed to relieve the swelling, and the subsequent, less frequently administered, prevent its re-development. While the number of injections is the highest in the first year, it drops significantly in the following year and treatment may be stopped in some patients. The physician decides about the need for administration based on the clinical condition, with particular emphasis on macular OCT. Although many patients are afraid of intravitreal injections, the risks associated with them are low and local anesthesia is comfortable. It happens that we perform several dozen such injections on one day, which is a certain logistical challenge. Research on other routes of administration of anti-VEGF drugs is ongoing. Perhaps in the future there will be effective preparations in drops or implants.
What is the reason for the advantage of anti-VEGF treatment over laser therapy?
The use of classic laser therapy leads to tissue coagulation, and thus is associated with the destruction of cells and the formation of scars in the retina, which can no longer perceive light stimuli. The swelling reduction is less than with VEGF inhibitors. This treatment is therefore less effective than anti-VEGF therapy and is associated with possible scotomas in the visual field. It serves more to preserve already reduced visual acuity than to improve it.
Laser therapy, which covers the entire macular area available by this method, cannot be repeated and is irreversible – the traces of laser impacts remain for life.
For these reasons, it is now a complementary method. Anti-VEGF therapy improves vision, leaving the retina intact. Recently, we also use micropulse lasers, which also do not damage the tissue. Such laser therapy can be repeated without harming the retina. Its efficacy is lower than that of VEGF inhibitors, but it can be expected that in the future the combination of micropulses and anti-VEGF preparations will become the first line treatment.
Doctor – is it available to patients in Poland?
All modern drugs are available in Poland. The only limitation in patients with DME is their very limited reimbursement. The costs associated with the use of VEGF inhibitors are high and constitute an insurmountable barrier for many people. For about a year, the AMD drug program has been operating in our country, which has allowed several thousand people to receive optimal therapy. It should be noted that the frequency of injections forced by the program is its great advantage – the payer has control over the quality of treatment, thanks to which we can be sure that our common money is not wasted. We look forward to starting a similar program in DME. We also hope for the popularization of micropulse lasers, which should be appreciated by the public payer.
Today, diabetic patients have the right to expect an ophthalmologist to fight to maintain full visual acuity – early detection of changes (screening) and appropriate, quickly implemented treatment make it possible.
Prof. dr hab. Sławomir Teper, President of the Polish Diabetes Society
Medonet is the patron of the “Diabetes under control” campaign.