Central vision, which depends on an eye structure called the macula, is what allows us to notice details and perform daily activities such as reading a book, driving, or even recognizing a person’s face. This type of vision is affected when a disorder known as macular degeneration occurs, a disease that affects older people most and ends up causing vision loss.

In this article we explain what macular degeneration is, what the two most common forms are and the symptoms associated with each. In addition, we tell you what the main risk factors are that lead to the appearance and development of this eye disease, as well as the treatments currently available.

What is macular degeneration?

Macular degeneration, also called age-related macular degeneration, is an inherited neurodegenerative eye disorder that gradually affects central vision, which is the vision that depends on the macula and provides us with the visual acuity needed to perform tasks such as driving, reading or recognizing a person’s face.

The macula is a tiny part of the eye, in the form of a yellowish spot (due to the high concentration of two pigments that give it that color), which is located in the central area of the retina. It is composed of the fovea, located inside the macula and responsible for the perception of colors; and the foveola, located inside the fovea, is what allows us to have maximum visual acuity.

In macular degeneration, as its name suggests, there is a progressive deterioration of the macula, which is what allows us to perceive details and movement , so people who suffer from this condition end up suffering significant loss of vision, especially related to fine details, either near or far.

This loss of central vision leads to a number of negative consequences in the daily lives of people with this condition, who are usually older. Macular degeneration is considered one of the main causes of blindness and low vision, and at the moment there is no known cure.

Currently, this disease affects 1.5% of the population , and if only people over 50 are considered, the prevalence increases to 5.3%. We will now look at the two main forms of macular degeneration.

Types and their symptoms

There are two types of macular degeneration: dry, which is the more common of the two; and wet, which is less frequent but more serious. Let’s take a closer look at what each one consists of.

Dry or atrophic macular degeneration

Dry macular degeneration is the most common type, accounting for 85% of all cases. The photoreceptors of the macula (the light-sensitive cells) and the retinal pigment epithelium deteriorate progressively, and deposits or extracellular waste products called drusen are formed.

The presence of drusen in the retina is relatively normal after the age of 45, and very common in people over 65. However, an increase in the amount and size of drusen is usually the first sign of possible macular degeneration. The result is blurred or spotty vision and loss of central vision.

Dry macular degeneration evolves slowly over time and develops in three stages:

Early stage

Presence of small and medium sized drusas, without loss of vision or symptoms .

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Middle stage

The person has medium to large drusen, and vision may appear with spots in the center of the visual field . Sometimes the subject may need more light for tasks that require attention to detail.

Advanced stage

Presence of multiple drusen deposits, destruction of retinal pigment epithelium and macula photoreceptor cells At this stage, blurred vision and, eventually, loss of vision occurs.

Wet or oozing macular degeneration

Wet or exudative macular degeneration is the least common form (about 15% of cases) but the most serious. It occurs when the blood vessels (which form the neovascular membrane) behind the macula begin to grow abnormally, causing fluid and blood to leak. These exudations end up causing scarring and, consequently, macular damage.

In this form of macular degeneration, loss of central vision occurs rapidly. It does not develop in stages, as with the dry form, and the damage is more severe. The most common initial symptom is seeing the straight lines deformed s, as if they had a wavy silhouette. Vision can become blurred or be lost completely in a very short period of time (days or weeks).

There are two subtypes of wet macular degeneration : the occult, which occurs due to fluid leaks and the growth of new blood vessels under the retina, and causes a milder loss of vision; and the classic, which is more severe in terms of vision loss and occurs because the growth of blood vessels and scarring generates large debris, responsible for the injury to the macula.

Risk factors

The main risk factor for macular degeneration is age, since for people over 50 the probability of suffering from this disease increases considerably. Other relevant factors that may increase the risk of this disorder include the following:

Family and genetic history

Macular degeneration is hereditary and several genes have been identified that may be involved in the development of the disorder, so the risk increases if you have a directly related family member who suffers from the disease .

2. Obesity

According to research, people suffering from obesity have a higher risk of passing from the early and middle stage to the advanced stage of
illness.

3. Smoking

Exposure to cigarette smoke on a regular basis increases the risk of disease, and patients who smoke respond less well to treatment .

4. Race

Caucasians are at greater risk for muscle degeneration than other races, such as African Americans.

5. Cardiovascular diseases and hypertension

There is a link between diseases affecting the heart or hypertension and macular degeneration.

6. Sex

Women are more likely to suffer from macular degeneration than men.

Treatment

Currently, there is no treatment that can prevent vision loss from dry macular degeneration when it reaches the most advanced stage. However, it is possible to stop or prevent the disease from progressing from the early stage to more advanced stages by using high doses of antioxidants and minerals such as zinc, according to the indications of the National Institute of Ophthalmology.

There are several therapeutic alternatives for treating wet macular degeneration: laser surgery, used to destroy the blood vessels that cause macular damage; photodynamic therapy, which involves injecting a substance into the body and then activating it by shining a light on the blood vessels in the eye; and injections into the eye with anti-VEGF drugs, which remove growth factors that promote the development of abnormal blood vessels.

However, macular degeneration and associated vision loss can continue to progress, even when treatment is in place. At the moment, there is no known cure or fully effective treatment , but research continues.

Bibliographic references:

  • Chávez Pardo, I., González Varona, D., & de Miranda Remedios, D. I. (2008). Age-related macular degeneration. Revista Archivo Médico de Camagüey, 12(2), 0-0.

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  • Curcio, C. A., Medeiros, N. E., & Millican, C. L. (1996). Photoreceptor loss in age-related macular degeneration. Investigative ophthalmology & visual science, 37(7), 1236-1249.
  • Flores-Moreno, S., & Bautista-Paloma, J. (2008). Treatment of age-related macular degeneration: a pending subject. Archives of the Spanish Society of Ophthalmology, 83(7), 405-406.