Pathological Myopia: Causes, Complications, Diagnosis, and Management

Introduction

Pathological myopia, also called degenerative myopia or malignant myopia, is a severe form of myopia associated with progressive elongation of the eyeball and structural changes in the retina, choroid, sclera, and optic nerve.

Unlike ordinary myopia, pathological myopia can continue to progress and may cause permanent visual impairment. It is particularly important because complications such as myopic maculopathy, posterior staphyloma, retinal detachment, and myopic choroidal neovascularization (CNV) can threaten central or peripheral vision.

Early detection, regular retinal monitoring, and appropriate treatment of complications are essential for protecting vision.

What Is Pathological Myopia?

Pathological myopia is a high and usually progressive form of myopia associated with abnormal elongation of the axial length of the eye and degenerative changes in the posterior segment.

High myopia is commonly defined as a refractive error of approximately −6.00 diopters (D) or more, while an axial length of 26 mm or greater is often used as an important anatomical marker.

However, pathological myopia is not defined simply by the strength of the spectacle prescription. The presence of characteristic structural changes and complications is particularly important.

Pathological Myopia vs Simple Myopia

Simple myopia:

• Usually develops during childhood or adolescence
• Often stabilizes in early adulthood
• Distance vision is blurred
• Usually corrected effectively with spectacles or contact lenses
• Does not necessarily cause retinal degeneration

Pathological myopia:

• Associated with excessive axial elongation
• May continue progressing
• Causes stretching and degeneration of ocular tissues
• Can produce retinal and macular complications
• May lead to irreversible visual loss

How Does Pathological Myopia Develop?

In a normal eye, the optical system focuses incoming light onto the retina.

In myopia, the eye is longer than normal or its refractive power is too strong, causing light to focus in front of the retina.

In pathological myopia, progressive axial elongation places mechanical stress on the tissues at the back of the eye.

This stretching can affect:

• Retina
• Choroid
• Retinal pigment epithelium (RPE)
• Bruch's membrane
• Sclera
• Optic nerve
• Macula

Over time, these changes can produce degenerative lesions and sight-threatening complications.

Causes and Risk Factors of Pathological Myopia

Pathological myopia is multifactorial. Both genetic and environmental factors can contribute.

1. Genetic Factors

A strong family history of high myopia increases the likelihood of developing severe myopia.

Multiple genetic factors influence:

• Eye growth
• Scleral remodeling
• Retinal development
• Axial elongation

Children with highly myopic parents may have a greater risk of developing significant myopia.

2. Excessive Axial Elongation

The most important structural factor is progressive enlargement of the eye's axial length.

As the globe becomes longer:

• The retina becomes stretched.
• The choroid becomes thinner.
• The sclera undergoes remodeling.
• The posterior pole may become distorted.

This creates the foundation for many complications of pathological myopia.

3. Early-Onset Myopia

Myopia that begins at a young age is more likely to become severe.

Early-onset myopia provides more time for the eye to elongate during childhood and adolescence.

4. Environmental Factors

Environmental factors associated with myopia development and progression include:

• Excessive near work
• Limited outdoor exposure
• Prolonged educational activities
• Extensive digital device use

These factors are particularly relevant to childhood myopia.

Symptoms of Pathological Myopia

Symptoms depend on the severity of myopia and the presence of complications.

Common symptoms include:

• Severe blurred distance vision
• Difficulty seeing without correction
• Distorted central vision
• Reduced visual acuity
• Difficulty seeing in low light
• Increased floaters
• Flashes of light
• Difficulty recognizing faces
• Difficulty reading
• Metamorphopsia

Some retinal complications may initially produce few symptoms, which is why regular retinal examinations are important.

Major Complications of Pathological Myopia

Pathological myopia can affect almost every structure of the posterior eye.

1. Myopic Maculopathy

Myopic maculopathy is one of the most important causes of visual impairment in pathological myopia.

Degenerative changes can affect the macula and lead to progressive central vision loss.

Clinical changes may include:

• RPE abnormalities
• Chorioretinal atrophy
• Patchy atrophy
• Macular atrophy
• Lacquer cracks
• Fuchs' spot

2. Posterior Staphyloma

A posterior staphyloma occurs when the posterior wall of the eyeball develops an abnormal outward protrusion.

It is strongly associated with pathological myopia.

Posterior staphyloma can distort:

• Retina
• Choroid
• Macula
• Optic disc

This distortion may contribute to progressive visual dysfunction.

3. Lacquer Cracks

Lacquer cracks are breaks or disruptions involving Bruch's membrane.

They appear as yellowish linear lesions in the posterior pole.

Lacquer cracks are clinically important because they may predispose to the development of myopic choroidal neovascularization.

4. Myopic Choroidal Neovascularization

Myopic CNV is one of the most important vision-threatening complications.

Abnormal blood vessels grow beneath or around the retina.

These vessels can leak:

• Blood
• Fluid

This may cause:

• Sudden reduction in vision
• Metamorphopsia
• Central scotoma
• Macular hemorrhage

If untreated, permanent macular damage may occur.

5. Retinal Detachment

Severe axial elongation increases mechanical stress on the peripheral retina.

This can contribute to:

• Retinal tears
• Retinal holes
• Rhegmatogenous retinal detachment

Warning Symptoms

Patients should seek urgent ophthalmic evaluation if they develop:

• Sudden increase in floaters
• Flashes of light
• A dark curtain or shadow
• Sudden loss of peripheral vision

6. Myopic Macular Hole

Severe myopia can increase tractional forces around the macula.

This may result in:

• Foveal deformation
• Foveoschisis
• Macular hole
• Retinal detachment associated with a macular hole

7. Myopic Traction Maculopathy

Progressive stretching of the posterior eye can produce tractional abnormalities involving the macula.

It may include:

• Foveoschisis
• Retinal thickening
• Lamellar macular holes
• Macular holes
• Tractional retinal detachment

Optical coherence tomography (OCT) is particularly useful for identifying these changes.

8. Optic Nerve Changes

Pathological myopia can alter the appearance of the optic nerve.

Possible findings include:

• Tilted optic disc
• Peripapillary atrophy
• Optic disc deformation

These changes can sometimes make glaucoma assessment more difficult.

9. Glaucoma

Highly myopic eyes may have an increased risk of glaucoma.

Diagnosis can be challenging because:

• The optic disc may be tilted.
• OCT measurements may be atypical.
• Visual field defects can overlap with myopic changes.

Therefore, glaucoma evaluation should consider multiple clinical parameters rather than relying on a single test.

10. Cataract

People with high myopia may have an increased risk of developing certain types of cataract.

Cataract can further reduce visual acuity and increase visual disability.

Diagnosis of Pathological Myopia

A comprehensive ophthalmic examination is essential.

1. Visual Acuity Testing

Measures the patient's ability to see at different distances.

Both uncorrected and best-corrected visual acuity may be documented.

2. Refraction

Determines the degree of myopia.

Refraction may be performed using:

• Autorefraction
• Retinoscopy
• Subjective refraction

3. Axial Length Measurement

Axial length is an important marker of ocular elongation.

It can be measured using optical biometry or other biometry techniques.

Serial measurements are useful for monitoring progression.

4. Dilated Fundus Examination

A dilated retinal examination helps identify:

• Retinal degeneration
• Lacquer cracks
• Peripheral retinal lesions
• Macular abnormalities
• Retinal tears
• Posterior staphyloma-related changes

5. Optical Coherence Tomography (OCT)

OCT provides high-resolution cross-sectional images of the retina.

It is particularly useful for detecting:

• Macular atrophy
• Foveoschisis
• Macular holes
• Subretinal fluid
• Retinal traction
• Choroidal neovascularization

6. Optical Coherence Tomography Angiography

OCTA can help identify abnormal retinal and choroidal vascular networks without intravenous dye.

It may be useful in evaluating suspected myopic CNV.

7. Fundus Photography

Serial photographs can help monitor progressive retinal and macular changes.

8. Fundus Fluorescein Angiography

Fluorescein angiography may be used when choroidal neovascularization is suspected and helps identify leakage from abnormal vessels.

Management of Pathological Myopia

There is currently no simple treatment that can reverse all structural changes caused by pathological myopia.

Management focuses on:

1. Correcting refractive error
2. Controlling myopia progression when possible
3. Detecting complications early
4. Treating sight-threatening complications
5. Monitoring retinal health

1. Spectacles

High-index spectacle lenses can provide optical correction.

Advantages include:

• Non-invasive
• Safe
• Easy to maintain

However, very high prescriptions can produce thicker lenses and optical distortions.

2. Contact Lenses

Contact lenses may provide better optical correction for some patients with high myopia.

Potential benefits include:

• Wider visual field
• Reduced image-size differences
• Better cosmetic appearance

Proper hygiene and professional fitting are essential.

3. Myopia Control

In children and adolescents with progressing myopia, strategies may be used to slow axial elongation.

Options may include:

• Low-dose atropine
• Myopia-control spectacle lenses
• Multifocal contact lenses
• Orthokeratology
• Increased outdoor activity

The appropriate approach depends on age, rate of progression, axial length, and clinical circumstances.

Treatment of Pathological Myopia Complications

Anti-VEGF Therapy for Myopic CNV

Anti-vascular endothelial growth factor (anti-VEGF) injections are the main treatment for active myopic choroidal neovascularization.

They work by reducing abnormal blood-vessel growth and leakage.

Treatment can improve or stabilize vision in many patients when initiated appropriately.

Surgical Treatment

Surgery may be required for certain advanced complications.

Examples include:

• Retinal detachment
• Macular hole
• Tractional maculopathy
• Severe vitreoretinal abnormalities

Procedures may include:

• Vitrectomy
• Retinal detachment repair
• Macular surgery
• Other vitreoretinal procedures

The specific procedure depends on the underlying pathology.

Can Pathological Myopia Be Prevented?

Complete prevention is not always possible because genetic factors play an important role.

However, controlling childhood myopia progression may reduce the risk of developing very high myopia.

Helpful measures include:

Encourage Outdoor Activity

Regular outdoor time is associated with a lower risk of myopia development in children.

Reduce Excessive Near Work

Encourage children to take regular breaks during prolonged reading or screen use.

Maintain Appropriate Working Distance

Books and digital devices should not be held extremely close to the face.

Regular Eye Examinations

Children with progressive myopia should undergo periodic assessment of:

• Refraction
• Visual acuity
• Axial length
• Retinal health

Pathological Myopia vs High Myopia

These terms are related but not identical.

High myopia generally refers to a high degree of refractive error, commonly around −6.00 D or more.

Pathological myopia refers to high/progressive myopia associated with characteristic structural changes or complications of the posterior eye.

Therefore, a person can have high myopia without having significant pathological changes, while pathological myopia is defined by the presence of degenerative ocular changes rather than prescription alone.

Prognosis

The prognosis varies considerably.

Some people with high myopia maintain good vision throughout life, while others develop progressive retinal or macular complications.

The risk of visual impairment increases when pathological changes such as:

• Macular atrophy
• Myopic CNV
• Posterior staphyloma
• Retinal detachment
• Myopic traction maculopathy

are present.

Regular monitoring allows complications to be detected and treated as early as possible.

When Should a Patient Seek Urgent Care?

A person with high or pathological myopia should seek urgent ophthalmic assessment if they experience:

• Sudden flashes of light
• A sudden increase in floaters
• Curtain-like shadow over vision
• Sudden central vision loss
• New distortion of straight lines
• Sudden decrease in visual acuity

These symptoms may indicate retinal detachment or other retinal complications.

Frequently Asked Questions About Pathological Myopia

Is pathological myopia the same as high myopia?

No. High myopia describes a high degree of refractive error, whereas pathological myopia involves structural and degenerative changes associated with excessive axial elongation.

Can pathological myopia be cured?

There is currently no treatment that completely reverses the underlying structural elongation and degeneration. However, vision can often be corrected, progression can be managed, and complications can be treated.

Can pathological myopia cause blindness?

Severe complications can cause significant and sometimes permanent vision loss. Early detection and treatment are therefore extremely important.

Can LASIK treat pathological myopia?

Refractive surgery can reduce dependence on glasses in selected patients, but it does not reverse retinal or macular changes caused by pathological myopia. Retinal health must be assessed carefully before considering surgery.

Does pathological myopia get worse with age?

Pathological changes may progress over time in some individuals. Regular retinal monitoring is important even when the spectacle prescription appears stable.

Key Takeaways

• Pathological myopia is more than a high spectacle prescription.
• Excessive axial elongation is a major underlying mechanism.
• It can cause progressive changes in the retina, choroid, sclera, and macula.
• Important complications include myopic maculopathy, posterior staphyloma, lacquer cracks, myopic CNV, retinal detachment, and traction maculopathy.
• OCT, fundus examination, fundus photography, and axial-length measurement are valuable monitoring tools.
• Anti-VEGF treatment is important for active myopic CNV.
• Vitreoretinal surgery may be required for selected retinal and macular complications.
• Children with progressing myopia may benefit from evidence-based myopia-control strategies.
• Sudden flashes, floaters, curtain-like vision, or sudden vision loss require urgent retinal evaluation.

Conclusion

Pathological myopia is a serious form of high myopia characterized by excessive axial elongation and progressive structural changes in the posterior segment of the eye. Although the refractive error itself can usually be corrected with spectacles or contact lenses, the associated retinal and macular complications require long-term ophthalmic monitoring.

Early identification of pathological changes, regular retinal examinations, appropriate myopia-control strategies in younger patients, and timely treatment of complications such as myopic choroidal neovascularization and retinal detachment can help preserve vision and improve long-term outcomes.