About myopic macular degeneration
Myopic macular degeneration (also known as MMD) can occur if you’re very short-sighted due to elongation of the eyeball. The stretching of the retina due to the elongation of the eye can result in tears in the macula area. It can also cause bleeding beneath the retina.
What is myopia?
Myopia is often also referred to as short-sightedness. Myopia occurs when the eyeball has grown too long. This means your eye isn’t able to focus light on the retina. As a result, vision is blurry in the distance but clear up close. It’s a very common condition. However, for most people, contact lenses or glasses will make vision clear.
The power of the glasses or contact lenses used to correct vision blur is measured in a unit call dioptres (D). So, the higher the number, the more myopic you are. High myopia is usually over -6.00 D.
Problems associated with high myopia
People with high myopia are at risk of pathological myopia. That’s where permanent degenerative changes can occur to the retina, due to elongation of the eye. Any of these degenerative changes can include the macula. Where they do, it’s called myopic macular degeneration.
These degenerative changes can include:
The stretching of the retina in myopia causes the retina to become thinner which can lead to areas of retinal atrophy (breakdown) and associated vision loss. Retinal atrophy can occur anywhere on the retina. If it happens in the central macula area, it can affect central vision.
As the eye stretches it can cause breaks to appear in a layer between the retina and the choroid called Bruch’s membrane. These breaks can also appear in the macula. They’re called lacquer cracks. Lacquer cracks also may be associated with choroidal neovascularisation. Retinal haemorrhages can also occur even without the presence of choroidal neovascularisation.
New blood vessels can grow in areas of atrophy or lacquer cracks and can involve the macula. This is known as choroidal neovascularisation (CNV). The new blood vessels are fragile with leaky walls and can lead to scarring and vision loss.
People with high myopia are at increased risk of retinal detachment due to the eye elongation and subsequent stretching of the retina. The most common symptoms are the sudden onset of flashes and floaters. Some people may also notice reduced vision or a curtain or shadow in the affected eye. Retinal tears are generally fixed with laser and retinal detachments normally require surgery.
Glasses and contact lenses are very effective in managing the blurriness caused by myopia in most cases. But they don’t reduce the impact of high myopia on the eye.
Unfortunately, the higher the level of myopia, the greater the risk of additional damage occurring to the retina due to the elongation of the eye. If your retina has been damaged, then you may need more than glasses to help you see better.
There’s ongoing research into the management of myopia in children to reduce the progression of eye elongation and therefore retinal damage with age. Therapies include the use of eye drops, speciality hard and soft contact lenses, and glasses.
Myopic macular degeneration treatment
If you have myopic macular degeneration, you need to be monitored regularly. Make sure you head to your eye health professional as soon as possible if you notice any sudden changes in vision or any new symptoms.
However, not all the eye changes that occur in pathological myopia can be treated.
If choroidal neovascularisation occurs, you may be treated with anti-vascular endothelial growth factor (anti-VEGF) eye injections or laser. But that will depend on the location.
You should always discuss the appropriate treatment with your eye health professional, to make sure you understand the options available.
Monitoring myopic macular degeneration
Even if your vision appears stable, it’s essential that you have a comprehensive eye exam at least once a year. Your eye health professional may recommend more frequent eye exams, so always follow their recommendations.
Managing vision loss
If you experience vision loss as macular myopic macular degeneration progresses, a key priority is maintaining quality of life and independence. Macular Disease Foundation Australia has resources that may help.