Age-related macular degeneration, from causes to therapies

On the causes of age-related macular degeneration there are not yet many certainties. We know, however, that something can be done in terms of prevention.

We talk about it with Leonardo Mastropasqua, ophthalmologist at the University of G. D’Annunzio, Chieti Pescara.

Age-related macular degeneration: what is it and what forms exist?

It is a pathology that involves the central area of the retina (macula), causing an irreversible reduction in distinct vision. It is the leading cause of blindness in industrialized countries after the age of 50 and is the cause of about 5% of global blindness. AMD is classified into a “dry” (non-exudative) form and a “wet” form (exudative or neovascular). The dry or atrophic form (80% of cases) is characterized by a progressive thinning of the central retina, with the death of light-sensitive nerve cells (photoreceptors) and the formation of a macular scar. In the exudative form (20% of cases) new abnormal capillaries form at the level of the macula with a very fragile wall which, breaking, cause the passage of plasma (the liquid part of the blood) in the retina or extravasation of blood. The persistence of new vessels and repeated bleeding at the level of the macula can cause a retinal scar with irreversible damage to the retina. Both forms are preceded by an early form of AMD characterized by the presence of rounded deposits of waste material under the retina (drusen).

What are the causes?

The causes of AMD have not yet been proven, but several risk factors have been identified: age over 50-55 years, female sex, cigarette smoking, alcohol abuse, diabetes mellitus, sedentary lifestyle, diet low in vitamins and unsaturated fatty acids (omega-3), arterial hypertension, coagulation disorders , prolonged and repeated exposure to very intense light sources. From a genetic point of view, numerous genes have been found associated with the risk of contracting it.

What are the first alarm bells?

Reduced visual acuity is the main symptom of the two forms of AMD, with a loss of the central part of the visual field (portion of space perceived by a motionless eye). The vision of crooked lines (metamorphopsias) is usually not present in the early stages. It usually manifests itself in the most advanced exudative forms due to the presence of retinal lifts.

What are the therapies for AMD?

For the dry form, there are preventive therapeutic measures that slow down its progression. A diet rich in antioxidants (fruits and vegetables or food supplements) is advisable, which can help fight the formation of free radicals. Under study for the atrophic form there are some drugs for intravitreal use (lampalizumab) able to block the inflammation that seems to be at the base of the disease. For the wet form there are photodynamic therapy and intravitreal injections with drugs that counteract the growth of abnormal vessels (anti-VEGF). Photodynamic therapy is based on a particular type of laser that activates an intravenously injected substance (verteporphyrin) allowing the occlusion of only abnormal vessels without damage to the surrounding retina. The most used anti-VEGF drugs in injection therapy are aflibercept, ranibizumab, bevacizumab and pegaptanib sodium: they have shown excellent results especially with repeated injections. In most cases they slow down the evolution of the disease and improve vision.

What are the benefits of the latest anti-VEGF drug approved in Italy?

Aflibercept, the latest drug approved for the intravitreal treatment of AMD, has shown equal efficacy compared to other anti-VEGF in controlling the disease with fewer injections. The lower need for injections is related to the longer duration of action of the drug and the ability to block more substances (VEGFA, VEGFB, PlGF) related to the growth of abnormal vessels. The reduced number of injections improves patient compliance with treatment and makes therapy more effective.