Macular Degeneration – Symptoms, Risk Factors, and Treatment

Age-related macular degeneration is considered to be the leading cause of legal blindness in Australia, accounting for half of all cases of blindness. Unfortunately, the vision loss caused by macular degeneration is irreversible and there is currently no cure that can guarantee to halt the progression of any vision damage.

However, there are some steps that can be taken to reduce your risk of developing the disease or suffering further vision loss in the presence of existing macular degeneration. 

What is Macular Degeneration? 

The macula is the anatomical part of the eye responsible for your central vision. The retina is the sensory layer of tissue lining the inside of the eyeball; the macula is a part of this that contains the highest density of photoreceptors, the sensory cells that detect and respond to light before the signals are converted to neural impulses that are then sent onward to the brain for visual processing. 

Macular degeneration is a disease that results in damage to the retinal tissues that support the high-energy function of these photoreceptor cells, known as the retinal pigment epithelium. Although there is still much more to understand about exactly why and how the damage occurs, we know that during age-related macular degeneration, metabolic waste material known as drusen begins to accumulate beneath the retinal pigment epithelium, interfering with the health and function of these tissues.

The resultant effect is that the photoreceptor layer, dependent on a healthy retinal pigment epithelium, also becomes damaged, leading to the characteristic macular degeneration symptoms of central vision deterioration. In more advanced stages of macular degeneration, known as the neovascular form, new blood vessels form under the retina, which is fragile and can leak blood and fluid, causing severe retinal damage and vision loss. 

There are several risk factors associated with the development of age-related macular degeneration. Some of these are modifiable lifestyle choices while others are simply the luck of the draw. 

• Age – the risk of macular degeneration increases with increasing age
• Family history of the disease – those with an immediate family member with macular degeneration are 50% more likely to develop the condition themselves
• Smoking – cigarette smoking has been linked with a 3 to 4 times increased risk of developing macular degeneration compared to a non-smoker, and smokers are also at risk of encountering the disease 5 to 10 years earlier than a non-smoker with all other things being equal 
• Systemic conditions – certain diseases, such as obesity and hypertension, have been linked to an increased risk of macular degeneration  

Macular Degeneration Symptoms

In most cases, macular degeneration symptoms occur gradually, and an individual with the disease may not even be aware of any changes to their vision for years. Macular degeneration symptoms can also be non-specific, meaning that they are not unique to macular degeneration and may be dismissed by a patient thinking they simply need an updated spectacle prescription.

Typically, macular degeneration symptoms can include: 

• Blurring of your central vision – this may not be immediately identifiable, but instead you may first begin to become aware of increasing difficulty with specific tasks that require detailed vision, such as reading text or recognising faces from a distance 
• Distortion in your vision – because of the formation of drusen disrupts the uniform, smooth layers of retinal tissues, you may see straight lines as wavy or curved
• Dark patches in your vision – significant areas of photoreceptor damage and death will result in complete loss of vision in that particular area of your retina, which you may perceive as a black hole in your field of view
• Sudden loss of central vision – in the case of wet macular degeneration, the loss of sight can be quite dramatic if a large retinal bleed were to occur 

Your peripheral vision is likely to remain unaffected. Macular degeneration symptoms can differ in severity between the eyes, and in some cases may only present in one eye while the other eye experiences no issues at all. 

Treatment

Currently, there is no treatment for dry macular degeneration. Management is aimed at addressing modifiable factors such as cigarette smoking and cardiovascular disease in an effort to slow the rate of vision deterioration. There are also nutritional factors that have been shown to be beneficial for the health of the macula, such as increasing your dietary intake of the antioxidants zeaxanthin and lutein. 

For the wet form of macular degeneration, modern therapies are most commonly in the form of an injection of medication into the eye rather than retinal surgery. These medications are known as anti-vascular endothelial growth factor (anti-VEGF) drugs and are designed to block the proteins produced by the retina in wet macular degeneration that trigger the formation of new blood vessels.

Laser retinal surgery procedures such as photodynamic therapy are very rarely used in the modern management of macular degeneration nowadays; in specific cases it may be used as an adjunct treatment if the condition cannot be controlled entirely with anti-VEGF injections.

Another type of laser retinal surgery known as laser photocoagulation employs the use of a high-energy thermal laser that aims to destroy and seal leaking blood vessels. However, this treatment also results in damage to the surrounding retina and so is only used in the minority of cases where the formation of new blood vessels occurs in the retina some distance away from the crucial central vision. 

As early intervention can help to identify what steps can be taken to reduce your risk of progressive vision loss from macular degeneration, it’s important to maintain regular eye examinations with your eyecare provider. 

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

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