High-myopia retinal risk

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Myopia brings distant images to a focus in front of the retina when accommodation is relaxed. Many affected eyes are longer than average, although refractive power also contributes. The International Myopia Institute uses a spherical equivalent of minus six dioptres or more negative to define high myopia. This is a classification threshold, not a biological boundary at which risk suddenly appears.

Pathological myopia is a different concept: structural damage involving the posterior segment, such as characteristic myopic macular degeneration or posterior staphyloma. Some highly myopic people retain excellent corrected vision without these changes; structural disease can also occur without meeting the numerical high-myopia threshold. Clinical assessment therefore combines the original prescription, ocular anatomy, current symptoms and observed lesions.

Key points

High myopia is a refractive category; pathological myopia describes structural posterior eye disease.
The International Myopia Institute defines high myopia as spherical equivalent at or below minus six dioptres.
Correction with glasses, contact lenses or corneal laser surgery does not reverse an elongated globe.
New peripheral symptoms suggest vitreoretinal traction; new central distortion suggests macular involvement.
A normal central acuity result cannot exclude a peripheral retinal tear.
Treat the demonstrated complication and tailor surveillance to the person's actual retinal findings.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Axial elongation

An elongated globe is an important cause of high myopia. Its posterior tissues experience altered geometry and mechanical stress, creating vulnerability that persists even when optical correction provides a sharply focused image.

Refractive and inherited contributions

Corneal and lenticular power influence measured refraction alongside axial length. Early severe myopia, relevant family history or additional systemic findings may justify specialist consideration of an inherited ocular or connective-tissue disorder.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Peripheral vitreoretinal stress
Changes in vitreous attachment and peripheral retinal structure can predispose to traction and retinal breaks. Fluid passing through a full-thickness break may separate the sensory retina from its supporting pigment epithelium.
2
Posterior structural deformation
Posterior staphyloma represents a localised outward deformation of the eye wall. Associated retinal and choroidal changes may impair macular function, with atrophy, tractional distortion or other structural complications developing in different combinations.
3
Myopic neovascularisation
Abnormal vessels may develop near the macula and leak or bleed. Damage to central retinal architecture produces distortion and reduced reading vision; subsequent scarring or atrophy may limit recovery even after vascular activity is controlled.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Recover the original ocular history

Ask about the strongest previous prescription, childhood onset, contact lenses, corneal refractive surgery and cataract operations. A current near-zero prescription after surgery can conceal a long-standing elongated eye. Record previous retinal tears, detachment, treatment and relevant findings in the fellow eye.

Separate peripheral from central change

Brief peripheral flashes and new mobile specks point towards vitreoretinal events. Bent lines, altered letter shapes or a stationary central patch suggest macular dysfunction. Ask the person to compare eyes separately; a good fellow eye can conceal substantial unilateral deterioration.

Examine beyond acuity

Measure corrected vision in each eye and document whether the current result differs from the person's usual function. Examine pupils, fields and the anterior segment as appropriate, then arrange an adequate dilated posterior examination. Good chart vision does not establish peripheral retinal safety.

Distinguish abnormal anatomy from active disease

Document the appearance and location of atrophy, pigment changes, peripheral lesions and any posterior staphyloma. New haemorrhage or fluid has different implications from stable longstanding changes. Compare previous images when available rather than assuming that every myopic-looking feature is progressing.

Red flags requiring action

A new fixed peripheral shadow or rapidly enlarging curtain requires emergency retinal assessment.
Sudden flashes accompanied by many new floaters require examination for a retinal break.
New central distortion, a dark reading spot or unexplained central blur warrants urgent macular assessment.
A sudden change after trauma or ocular surgery must not be attributed to the existing refractive error.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
Refraction and relevant biometryFirst step
Why
Characterise optical error and recover evidence of axial elongation.
Interpretation and limitations
Spherical equivalent combines spherical power with half the cylindrical power. Refraction classifies myopia but cannot by itself diagnose pathological myopia; a post-refractive-surgery measurement may understate the original anatomical risk.
02
Dilated retinal examination
Why
Assess peripheral breaks and posterior structural complications directly.
Interpretation and limitations
New flashes or floaters require a sufficiently complete peripheral examination by a competent practitioner. A central photograph or reassuring macular scan cannot exclude an anterior peripheral retinal tear.
03
Macular optical coherence tomography
Why
Identify anatomical explanations for new central visual symptoms.
Interpretation and limitations
OCT can demonstrate traction, retinal layer separation, macular holes and fluid associated with neovascular activity. The specialist integrates the scan with examination and may use angiographic testing when lesion activity or mechanism remains uncertain.
04
Targeted glaucoma assessment
Why
Investigate suspicious optic nerve findings or functional visual loss.
Interpretation and limitations
Interpret pressure, disc appearance, visual fields and retinal nerve imaging together. Myopic anatomy can create segmentation or normative-database errors; repeat reliable measurements and longitudinal comparison are more informative than accepting a colour-coded scan result uncritically.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Uncorrected optical blur

An outdated prescription can reduce distance clarity without causing retinal disease. Improvement with refraction is useful, but a coincidental refractive error does not adequately explain new flashes, a fixed field defect or central distortion.

Myopic macular traction

Vitreoretinal forces can distort or split retinal layers and may accompany a macular hole or local detachment. Optical coherence tomography characterises this anatomy; management differs from treatment of an active neovascular lesion.

Other macular and optic disease

Cataract, glaucoma and non-myopic retinal disorders can coexist with high myopia. Attributing every visual complaint or abnormal scan to the prescription can obscure a second treatable cause of reduced vision.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01Acute peripheral symptomsExclude a retinal breakFirst stepNew flashes, a shower of floaters or a peripheral shadow develops.

1Arrange urgent dilated retinal assessment, using emergency same-day access for suspected tear or detachment.
2Record acuity, symptom onset, field change and relevant prior surgery without delaying referral.
3Ensure written return advice and a clear follow-up plan after the examining clinician establishes the findings.

02New central symptomsIdentify an active macular complicationNew distortion, central scotoma or unexplained central acuity loss occurs.

1Arrange prompt urgent retinal assessment instead of simply prescribing stronger spectacles.
2Use examination and macular imaging to distinguish active neovascularisation from traction, atrophy and other causes.
3Offer lesion-specific specialist treatment and explain which components of visual loss may be reversible.

03Stable high myopiaMaintain proportionate surveillance and independenceThe person has stable vision without a new retinal symptom.

1Agree review frequency from ocular findings, previous events and the eye-care team's assessment.
2Explain warning symptoms in language the person can recognise and provide an accessible route for urgent reassessment.
3Address optical correction, task lighting, protective eyewear and rehabilitation according to functional need.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

Suppresses abnormal vascular activity when a retinal specialist identifies treatable myopic neovascularisation. NICE TA298 supports ranibizumab for this indication within its recommendation conditions; product selection follows the commissioned pathway.

Ranibizumab for active myopic choroidal neovascularisation

For the Lucentis 10 mg/mL product, an ophthalmologist administers 0.5 mg in 0.05 mL intravitreally. Subsequent injections depend on disease activity; doses into the same eye must be at least four weeks apart. Myopic neovascularisation does not require an automatic fixed three-injection course.

Exclude ocular or periocular infection and active severe intraocular inflammation. Monitor intraocular pressure and optic nerve perfusion, and provide urgent post-injection pain, redness or declining-vision instructions. Discuss previous stroke or TIA and pregnancy plans; avoid pregnancy exposure unless benefit outweighs risk, wait at least three months after the last dose before conception, and breastfeeding is not recommended during Lucentis treatment. Arrange monitoring during the first week after injection for infection, alongside the immediate pressure and perfusion checks. Use effective contraception during treatment.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Retinal detachment

A retinal break can lead to progressive separation and permanent visual loss, particularly if central retinal function becomes involved. Successful refractive correction does not remove the need to recognise warning symptoms promptly.

Central visual impairment

Myopic macular atrophy, neovascular scarring and tractional changes may compromise reading and face recognition. Optical aids and rehabilitation remain useful when residual structural damage limits the benefit of disease-specific treatment.

Complex glaucoma assessment

Myopic disc shape and retinal anatomy can complicate interpretation of nerve imaging and visual fields. Glaucoma assessment requires correlation between examination, reliable functional testing and change over time rather than an isolated automated label.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Record baseline corrected acuity, relevant peripheral findings and macular imaging so that future change can be assessed against the individual eye.
Review the effectiveness of optical correction while keeping retinal surveillance distinct from refraction alone.
After neovascular treatment, assess symptoms, vision and anatomical activity; recurrence can require further injections despite a previous good response.
If structural visual loss persists, arrange low-vision support and assess reading, work, mobility and driving needs rather than waiting for complete disease resolution.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Refractive surgery changes the optics

Corneal laser treatment can greatly reduce spectacle dependence without shortening an elongated globe. Patients may understandably believe that their myopia has been removed; explain that previous retinal risk remains relevant to new symptoms and future eye examinations.

Not every peripheral lesion needs identical treatment

Decisions about a peripheral degeneration, hole or tear depend on symptoms, traction, lesion characteristics and the wider retinal history. Prescription strength alone does not determine whether prophylactic laser is appropriate. A symptomatic lesion needs timely specialist assessment rather than a blanket treatment promise.

Useful surveillance has a clear purpose

An individual with stable high myopia and preserved function has different needs from someone with previous detachment, active macular disease or difficult-to-interpret glaucoma tests. Explain what each planned visit is monitoring and which changes should bring the next appointment forward.

Activity advice should preserve function

Discuss eye protection for contact-risk activities and occupational hazards. Tailor restrictions to a recent retinal event or an operation and the treating team's advice; avoid presenting high myopia alone as a reason for lifelong inactivity or dependence.

11Common pitfallsFrequent interpretation and management errors.

01
Assuming that unaided normal vision after laser correction means the eye no longer carries its previous anatomical retinal risk.
02
Calling every eye beyond minus six dioptres pathological without examining for structural posterior disease.
03
Treating new central distortion as an ordinary spectacle change without considering an active macular complication.
04
Using a reassuring OCT image of the macula to exclude a peripheral retinal break.
05
Promising that anti-VEGF treatment will reverse established atrophy or every cause of myopic visual loss.