Myopic macular degeneration: a vision threatening complication of nearsightedness

By ClearSight, 22 February, 2024

Controlling nearsightedness is crucial due to myopia’s potential long-term consequences, including myopic macular degeneration (MMD). Start early.

Have you ever wondered why it’s crucial to slow or halt the progression of nearsightedness in children? After all, it is likely that you can correct their eyesight to perfect 20/20 vision with glasses, contacts, or even laser surgery once they grow up.

It turns out that nearsightedness may raise the risk of vision-threatening eye problems later in life, including myopic macular degeneration, retinal detachment, glaucoma, and cataracts. In support of Low Vision Awareness Month, let’s delve into one of these conditions: myopic macular degeneration.

Navigating key terms in myopic macular degeneration

Myopic macular degeneration (MMD) is a condition that is becoming better understood through ongoing research. Here are some important terms and definitions you should know before starting.

Myopia: This is a common refractive error where distant objects appear blurry. It happens most commonly when the eyeball is too long or, in some cases, when the cornea is too curved, causing light to focus in front of the retina instead of on it.

High Myopia: This is a more severe form of myopia, typically defined as more than -5.00 to -6.00 diopters (D). It is often confused with pathologic myopia, which is when there are degenerative changes in the back of the eye.

Pathologic Myopia: This occurs when the eye grows too long, leading to changes in the back of the eye. These changes can cause issues like blurry vision, difficulty seeing in low light, and even vision loss.

Myopic Macular Degeneration (MMD): Also known as myopic maculopathy (MM), MMD is one of the most common types of pathologic myopia. It occurs when the retina cells responsible for sharp, detailed vision in the eye start to die, leading to a gradual loss of central vision.

Myopic Chorioretinal Neovascularization (myopic CNV): This is also referred to as myopic macular neovascularization (MNV) in many research publications. It occurs when new blood vessels grow abnormally under the macula. As blood and fluid leak into the macula, it damages the retina cells, leading to vision loss. Because of this, it is also referred to as the wet type of MMD.

Causes of myopic macular degeneration

Myopic macular degeneration, a condition affecting the macula, the central part of the retina, can lead to blurry or distorted vision, dark spots in the field of view, and a gradual decline in visual acuity.

A commonly asked question by worried parents is, does it mean my child may be at risk of becoming blind? Contrary to the detrimental impression, this condition does not cause complete blindness but rather impairs central vision (like the above picture). The confusion often stems from the term "legal blindness," which is used to determine eligibility for driving or disability insurance – a visual acuity of worse than 20/200 or field of vision that is less than 20 degrees.

The exact cause of myopic macular degeneration remains unclear. Several factors are thought to contribute to its development. These include the elongation of the eye, thinning at the back of the eye, cracks in the retina, and protrusion or bulging of the back part of the eye.¹ However, it is important to know that early detection and intervention can help manage and potentially prevent irreversible vision loss due to MMD.

How may myopia increase the risk of myopic macular degeneration?

Research showed that the risk of developing myopic maculopathy increases with the severity of myopia. For instance, individuals with a spherical error (SPH) ranging from -1.00 to -3.00 diopters (D) face a risk of 2.2 times higher than those without myopia. This risk escalates significantly for those with higher degrees of myopia: from 9.7 times for SPH between -3.00 to -5.00 D, to a staggering 348.6 times for those with over -9.00 D.²

Degree of Myopia (SPH)	Risk of Myopic Maculopathy
-1.00 to -3.00 D	2.2 times higher
-3.00 to -5.00 D	9.7 times higher
-5.00 to -7.00 D	40.6 times higher
-7.00 to -9.00 D	126.8 times higher
More than -9.00 D	348.6 times higher

Moreover, age is also a significant risk factor, particularly for individuals aged 50 or older with high myopia. Since most people’s myopia stabilizes in their twenties, regular eye check-ups with eye doctors and keeping an eye on the condition is important.

Furthermore, studies revealed disparities in the prevalence of pathologic myopia across different ethnic groups and regions. In Asian populations, approximately 1-3% were affected by pathologic myopia, with it being identified as the primary cause of blindness (legal) in several Asian countries. Conversely, in Western countries, it ranked as the third leading cause of blindness.

Can myopic macular degeneration be prevented?

Myopic macular degeneration is vision-threatening, and managing myopia's progression from a young age may reduce its risk. However, this can be challenging because it requires parental awareness and commitment, as children are typically too young to understand or afford the necessary interventions.

Fortunately, recent years have seen significant advancements in our understanding of myopia, leading to the development of interventions that can slow down or halt myopia progression. Medical interventions may include atropine eye drops, myopia-control glasses, or contact lenses. Moreover, research has also indicated lifestyle interventions to be helpful, for example, more outdoor time , regular eye breaks (five-minute breaks every 30- 60 mins), and appropriate screen distance.

It's crucial to note, however, that most myopia control treatments in the US have not yet received FDA approval and are used off-label. This includes atropine and myopia-control glasses. Therefore, you should collaborate closely with eye care professionals to discuss these interventions thoroughly, making an informed decision that is best suited for your child's needs.

Can myopic macular degeneration be treated?

Myopic CNV, a severe subtype of this condition, is characterized by the growth of new blood vessels from the weakened area in the back of the eye. A study estimated that 5-10% of eyes with myopic macular degeneration were at risk of developing myopic CNV.

Once active myopic CNV is diagnosed, prompt treatment should be initiated as soon as possible. Anti-VEGF therapies, the current standard of care, have shown good efficacy in treating myopic CNV and may restore some or most of the vision loss if treated early. This indicates that early detection and intervention may help patients reduce the likelihood of permanent vision impairment.

Key takeaway

Understanding the importance of managing and controlling nearsightedness in children is crucial due to its potential long-term consequences, including myopic macular degeneration (MMD). MMD may lead to loss of central vision and is correlated with the severity of myopia. While the exact cause remains unclear, factors such as eye elongation and thinning at the back of the eye contribute to its development. Preventing MMD involves controlling myopia progression from a young age. It is important to have eye examinations regularly since early diagnosis and prompt treatment could result in the most favorable treatment outcomes.

So, start early for the future of your child's eye health.

Want to stay connected on the newest happening? Join me

Facebook group: www.facebook.com/groups/myopia/

Pinterest board: https://www.pinterest.com/clearsightcorner/