Definition

Age-related macular degeneration (AMD) is the major cause of severe and irreversible visual reduction in individuals over the age of 65. It is a condition that affects the central portion of the retina, the macula, the site of distinct vision. AMD is commonly classified using the terms “early” (or dry) and “evolved” (in the exudative or neovascular, and atrophic forms).

Symptomatology

The main symptoms to be attributed to the presence of macular degeneration are represented by the appearance of image distortion (metamorphopia), by the vision of a central fixed spot (scotoma), by a reduction in visual acuity often associated with altered color vision and, frequently, by the vision of small images (micropsy).  Image distortion is often the first and most alarming symptom of macular degeneration, or it is also a warning sign of the reactivation of a pre-existing lesion in already affected patients. Patients with early AMD have retinal lesions, such as drusen and areas of altered pigmentation (predominantly hyperpigmentation), but almost always maintain a good level of visual acuity.

Evolved or neovascular AMD causes severe loss of visual ability, leading to the formation of a central scotoma (central zone of blindness) secondary to the formation of new vessels near or in the center of the macula. The risk factors currently known, in addition to advancing age, are represented by: cigarette smoking (risk 3 times higher than in non-smokers), familiarity (risk 4 times higher in blood relatives of subjects affected by the disease), sex (higher prevalence in women), race and ethnicity (higher prevalence in white race), refractive error (for each diopter of hypermetropia there is a 5% increased risk of developing AMD), iris color (eyes with dark irises rich in melanin and therefore well pigmented would seem more protected from oxidative damage induced by light), cataract (subjects with a history of cataract surgery have a statistically significant risk of progression or development of advanced AMD), arterial hypertension, alcohol consumption, exposure to sunlight.

Diagnostics

The diagnosis of macular degeneration is made through the evaluation of subjective symptoms reported by the patient, through the observation of characteristic lesions on ophthalmoscopic examination of the ocular fundus and thanks to the help of now consolidated imaging techniques such as fluorescent angiography (FAG), indocyanine green angiography (ICG) and Optical coherence tomography (OCT and Angio OCT).
Each of these methods allows, in fact, the visualization of the specific characteristics of the type of lesion, their classification and monitoring over time, thus being extremely useful also for the evaluation of the effectiveness of any treatment.
It is therefore useful to provide the patient with early AMD with a self-test – the Amsler test – an easy-to-execute test that allows to highlight the onset of this symptom and to monitor its progress over time.
The examination is performed using a square grid pattern placed at the distance of 30 cm that must be observed with the best correction for reading. After covering one eye with the hand, with the uncovered eye the patient must fix the central black spot of the reticle. If the surrounding lines appear wavy, deformed, or discontinuous, the patient should contact an eye doctor immediately.

Therapy

Prevention is the first step in the treatment of macular diseases.  For some years now, there has been an increasing use of anti-angiogenic drugs in the treatment of AMD. These drugs act by inhibiting VEGF (Vascular Endothelial Growth Factor), the growth factor underlying the development of the new vessels responsible for the most advanced and aggressive forms of the disease, thus preventing its growth.
Photodynamic therapy, on the other hand, is among the first therapies created for the treatment of neovascular AMD, still used today only in some and particular forms of neovascularization, especially for the treatment of so-called "polypoidal" forms alone or in combination therapy with anti-VEGF drugs.
There is also Laser Thermal Therapy (Photocoagulation), used only for the treatment of some forms of macular degeneration, intended only for those cases in which the lesion appears localized outside the central portion of the macula (extrafoveal neovascularizations).
Finally, there is surgical therapy: in recent years, some surgical techniques have been used in patients with exudative macular degeneration, particularly macular translocation and sub-macular surgery. However, due to the high risks of these techniques and the difficulty of performing surgical procedures, they are unlikely to become common in the treatment of these diseases, even if future research on selected patients more convincingly demonstrates their benefits.