What is High Myopia

High myopia, often defined as a refractive error of -6.00 diopters or more or an axial length of 26 millimeters or greater, is a significant vision condition that increases the risk of sight-threatening eye diseases. Unlike common nearsightedness, high myopia involves structural changes to the eyeball that can lead to long-term complications, making regular monitoring by an eye care professional essential.

What is the definition and pathophysiology of high myopia?

High myopia is a severe form of nearsightedness where the eyeball grows too long from front to back (axial elongation). This excessive growth causes light to focus in front of the retina rather than directly on it, resulting in blurred distance vision. Beyond simple refractive error, high myopia often involves the thinning and stretching of the retina, choroid, and sclera. This structural stretching is the primary mechanism that differentiates high myopia from low or moderate nearsightedness, as it creates a vulnerability to retinal detachment, myopic macular degeneration, and glaucoma.

What are the primary classifications and subtypes of high myopia?

Clinicians generally categorize high myopia into two main types to guide management and prognosis:

• Simple High Myopia: Often develops during childhood or adolescence and stabilizes in adulthood. It is primarily driven by a combination of genetic predisposition and environmental factors.


• Pathological (Degenerative) Myopia: This is a more severe form characterized by progressive axial elongation that continues into adulthood. It is defined by the presence of chorioretinal lesions, staphyloma (a bulging of the eye wall), or other degenerative changes that can lead to permanent vision loss.

How common is high myopia and who is affected?

The prevalence of high myopia is rising globally, with current estimates suggesting it affects approximately 2-5% of the global population, though regional variation is significant. It is typically diagnosed in childhood or early adolescence, though the degenerative form may progress throughout a patient's life. While there is no major gender disparity, geographic factors play a massive role; East Asian populations, for example, have reported significantly higher rates of high myopia compared to other ethnic groups. Currently, 78 people with high myopia have joined the DiseaseMaps community to share their experiences, highlighting the importance of peer support in managing the psychological and practical challenges of the condition.

What differentiates high myopia from standard nearsightedness?

While standard nearsightedness (low myopia) is usually a manageable refractive issue corrected with glasses or contacts, high myopia is considered a systemic ocular health risk. Key differences include:

1. Axial Length: In high myopia, the eye exceeds 26mm in length, which physically stretches the internal tissues of the eye.


2. Structural Integrity: The retina in a highly myopic eye is often thinner and more prone to tears or detachments.


3. Disease Risk: Patients are at a statistically higher risk for developing myopic maculopathy, which can lead to central vision loss that cannot be fully corrected with lenses.

Next steps

• Schedule a comprehensive dilated eye exam with an optometrist or ophthalmologist at least annually to monitor retinal health.


• Discuss myopia control strategies with your specialist, such as atropine drops, orthokeratology (Ortho-K), or special contact lenses, especially for younger patients.


• Join the DiseaseMaps.org community to connect with other members who share your experience and exchange information on managing the impact of high myopia.


• Educate yourself on the warning signs of retinal detachment, such as a sudden increase in floaters or "curtain-like" shadows in your vision.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD) - Myopia.


• Orphanet: Portal for rare diseases and orphan drugs.


• OMIM (Online Mendelian Inheritance in Man): Entry for Myopia.


• International Myopia Institute: Clinical guidelines and research reports.