The number one killer that endangers the eyesight of the elderly - macular degeneration!

Author: Ma Zhizhong, Chief Physician, Peking University Third Hospital

Reviewer: Tian Bei, Chief Physician, Beijing Tongren Hospital, Capital Medical University

During routine physical examinations, we often hear questions about macula. Macula is not a disease. Everyone has a macula in their eyes. The macula is a very important structure in the eye.

So what exactly is the macula? And what is macular degeneration?

1. What is the macula?

Under normal circumstances, the eye is a spherical structure with an important layer of tissue inside that is responsible for receiving and processing light signals, called the retina. The macula is part of the retina, located at the posterior pole of the fundus, the center of the retina. It is the thinnest and most visually sensitive area on the retina, and is also the most special and important part of the retinal tissue.

Figure 1 Original copyright image, no permission to reprint

The macula is equivalent to the central processor of the retina. It is the place where the photoreceptor cells are most concentrated. There are three types of cone cells: L-type, which is sensitive to red light; M-type, which is sensitive to green light; and S-type, which is sensitive to blue light. The macula has three major functions, namely light perception, color perception, and shape perception. When light enters the eyeball and is projected on the fovea in the macula, a clear and accurate image can be formed. In other words, the macula is indispensable for our ability to see the colorful world.

The macula plays a decisive role in the quality of vision. If there is a problem with the macula, vision will be significantly affected, manifested as decreased vision, visual distortion, central dark spots, etc. Many diseases can occur in the macula, such as macular edema, macular holes, macular degeneration, and macular damage.

2. What is macular degeneration?

The macula has a very high demand for oxygen and nutrition. With age, as well as the influence of various factors such as bad living habits and living environment, malnutrition, chronic light damage, etc., the macula in the retina atrophies or metabolism becomes abnormal, leading to structural changes and functional decline in the macula, resulting in abnormal vision. This is macular degeneration.

Macular degeneration is closely related to heredity. It is called a multi-gene genetic disease and is inherited in the family. For example, if the father or grandfather has had age-related macular degeneration, the offspring are more likely to develop it and have a greater genetic susceptibility.

Age-related macular degeneration is very common. The incidence rate gradually increases after the age of 55, and the older you are, the higher the incidence rate of macular degeneration. Age-related macular degeneration has a particularly serious impact on vision and is irreversible. It is the number one killer that affects vision in people over 60 years old.

Age-related macular degeneration is divided into dry and wet forms. Dry macular degeneration usually develops slowly, with a slow onset, and the vision of both eyes gradually deteriorates, with little impact on vision. In the early stages, yellow-white, circular exudates of varying sizes appear in the macula and posterior pole of the eye, called drusen. In the late stages, the pigmentation of the macula becomes disordered and atrophies.

Wet macular degeneration develops rapidly and starts relatively quickly. Vision may drop sharply in a few months or even a few days. In the early stage, new blood vessels invade the macular area, the fundus is dark red, and there may even be dark black hemorrhages. The macular area may bulge. When there is a large amount of bleeding, the blood may break through the retina and enter the vitreous body, causing vitreous hemorrhage. In the late stage, the hemorrhage under the macula becomes organized and forms a discoid scar.

Figure 2 Original copyright image, no permission to reprint

Simply put, wet macular degeneration is the most serious and fastest-acting threat to vision.

3. What tests can be used to diagnose macular degeneration?

When elderly people experience decreased vision and macular degeneration is suspected, they generally need to undergo vision tests, fundus examinations, optical coherence tomography (OCT), and fluorescent angiography.

Visual acuity test to understand the degree of vision loss. Fundus examination is mainly done by directly observing whether pathological changes occur in the fundus through an ophthalmoscope. Optical coherence tomography (OCT) is a tomographic scan of the retina, which can determine whether there are changes such as new blood vessels, edema, and hemorrhage in the macula. Fluorescein angiography is an intravenous injection of fluorescein to color the new blood vessels in the macula to determine whether there is leakage.

Currently, the most effective and simplest examination method is OCT examination, which has a diagnosis rate of 100%, is very accurate, inexpensive, and painless. It is an ophthalmic CT examination.

In special circumstances, such as when the vision is not particularly clear and it is difficult to judge whether the lesion is stable or unstable, fundus fluorescein angiography can be performed to clarify the situation.