What is Degenerative Myopia?

Myopia, or nearsightedness, is a common condition that is typically corrected using glasses or contact lenses.

However, in some cases, myopia can develop into degenerative myopia which is a medical condition and may require additional treatments.

Basics of Myopia

Myopia occurs when the eye is too long, or the power of the eye is too strong. In either case, the eye is unable to focus an image clearly when looking in the distance.

This gives the term “nearsightedness” as a person with myopia is able to see things up close clearly.

To correct myopia, glasses or contact lenses with a negative dioptric power can be prescribed by an eye doctor.

Physiology of Degenerative Myopia

Not all people who require glasses to see clearly in the distance are at risk of developing degenerative myopia, in fact, the vast majority are at little to no risk of developing degenerative myopia.

For a person to develop degenerative myopia, the refractive power of the eye must be at least a -6.00D power or the eye itself must be 26 millimeters long.

For a case to be classified as degenerative myopia, there must be progressive alteration to the globe, the actual eyeball, as opposed to only changes in the strength of the eye.

Both of these conditions are rather extreme and unlikely to develop if not present by adolescence.

When Degenerative Myopia Develops

Most cases of degenerative myopia convert from traditional myopia in the teenage years.

Once the conversion to degenerative myopia occurs, the condition can continue to worsen for decades and may only stabilize in the fifth or sixth decade of life.

How Does Degenerative Myopia Affect the Eye?

Other than causing the eye to be longer or stronger than normal, degenerative myopia can affect the back portion of the eye – the retina – in many ways.

Common retinal findings are a malinserted optic disc, peripapillary atrophy, or a posterior staphyloma.

More severe associated retinal findings include a retinal detachment, retinal degeneration, or choroidal neovascularization.

Degenerative Myopia and Retinal Detachments

In degenerative myopia, the eye is elongated, and the retina becomes very stretched in the back of the eye.

The stretching of the retina can result in breaks or tears in the retina. These breaks can cause the retina to become detached from the eye.

Retinal detachments can cause sudden loss of vision and if the retinal detachment is not repaired, it can cause permanent blindness in an eye.

Degenerative Myopia and Retinal Degeneration

Degenerative myopia is associated with several forms of retinal degeneration. Retinal degeneration occurs when a portion of the retina becomes damaged and the tissue at that area dies.

In most retinal degeneration, the damage occurs in the periphery and has only mild impact on vision.

But in some retinal degeneration that is associated with degenerative myopia, the damage occurs near the center of the back of the eye where vision is more affected.

There are treatments to prevent retinal degeneration from worsening but any vision that is lost or damaged will be permanent.

Degenerative Myopia and Choroidal Neovascularization

Among the most severe complications of degenerative myopia is choroidal neovascularization.

Choroidal neovascularization results from new blood vessels growing in the back of the eye and causing damage to the existing blood supply in the eye.

Additionally, these new blood vessels are leaky and unstable and can result in damage to the retina around them.

In cases of choroidal neovascularization, injections of anti-VEGF medications can provide the best outcome and prevent loss of vision permanently.

How to Detect and Prevent Degenerative Myopia

Early and yearly eye exams are important for all ages, especially children. In cases of high myopia, some form of myopia control may be used to slow the progression of the myopia and reduce the risk of developing degenerative myopia.

There are several options available for myopia control, but none can guarantee to prevent any progression of myopia but reducing the progression will significantly reduce the risk of degenerative myopia later in life as well.