What is the treatment for Myopic Choroidal Neovascularization (CNVM)?

Myopic Choroidal Neovascularization (mCNV): Definition and Treatment

What is Myopic CNVM?

Myopic choroidal neovascularization (mCNV) is the most common sight-threatening complication of pathologic myopia, characterized by abnormal blood vessel growth from the choroid through Bruch's membrane into the subretinal space, leading to sudden central vision loss that progresses to irreversible macular atrophy and fibrosis within 5 years if untreated. 1, 2

Clinical Characteristics

• mCNV typically presents with sudden onset of central vision loss in highly myopic patients, distinguishing it from the gradual vision changes seen in other myopic complications 2
• The condition affects approximately 5-11% of patients with pathologic myopia and carries a 35% risk of bilateral involvement within 8 years 2
• Natural history without treatment results in expanding macular atrophy and/or fibrosis, causing permanent vision loss 3, 1

Diagnostic Approach

• Fluorescein angiography (FA) is required to confirm the diagnosis before initiating treatment 2
• Optical coherence tomography (OCT) provides high-resolution cross-sectional imaging to assess intra- or subretinal fluid and monitor disease activity 4
• OCT angiography (OCTA) is a non-invasive technique for visualizing the neovascular network 5
• Indocyanine green angiography (ICGA) may be helpful when polypoidal components are suspected 5

First-Line Treatment: Anti-VEGF Therapy

Intravitreal anti-VEGF agents are the recommended first-line treatment for mCNV and should be initiated promptly upon diagnosis confirmation. 4, 6, 1, 2

FDA-Approved Anti-VEGF Agents

• Ranibizumab (0.5 mg) is FDA-approved specifically for myopic CNV 4
• In the pivotal mCNV trial, ranibizumab demonstrated mean visual acuity improvement of +12.1 to +12.5 ETDRS letters at 3 months, compared to +1.4 letters with photodynamic therapy (PDT) 4
• 37-40% of ranibizumab-treated patients gained ≥15 letters versus 14.5% with PDT 4

Treatment Regimen

Two evidence-based retreatment strategies are equally effective: 4

1. Vision stability-guided: Retreat when best-corrected visual acuity (BCVA) changes compared to the two preceding monthly values (mean 2.5 injections over 3 months)
2. Disease activity-guided: Retreat when BCVA decreases with intra/subretinal fluid or active leakage on OCT/FA compared to previous visit (mean 1.8 injections over 3 months)

• 41% of patients required only 1-3 injections with no further treatment needed 4
• Early treatment is critical to avoid late-stage complications including irreversible macular atrophy 3, 1

Comparative Efficacy

Bevacizumab and ranibizumab demonstrate equivalent efficacy with moderate certainty of evidence 7

• At 1 year, bevacizumab and ranibizumab showed no significant difference in visual outcomes (MD -0.02 logMAR, 95% CI -0.11 to 0.06) 7
• Anti-VEGF therapy is superior to PDT at 1 year (mean improvement -0.14 logMAR, equivalent to 7 ETDRS letters better, 95% CI -0.20 to -0.08) 7
• At 2 years, anti-VEGF maintained superiority over PDT (mean improvement -0.26 logMAR, equivalent to 13 ETDRS letters better) 7
• Aflibercept showed significant benefit versus sham at 1 year (MD -0.19 logMAR, equivalent to 9 ETDRS letters) 7

Alternative Treatments (Historical Context)

Photodynamic Therapy (PDT)

PDT is no longer recommended as first-line therapy but may be considered in anti-VEGF resistant cases, though evidence is limited 6

• The effectiveness of laser photocoagulation for myopic CNV has not been established, with one guideline noting potential vision-threatening complications from enlargement of atrophic laser scars 5
• PDT involves systemic administration of verteporfin followed by nonthermal light application to the macular pathology 5

Laser Photocoagulation

Laser photocoagulation is inferior to anti-VEGF therapy and not recommended 7

• Bevacizumab showed superior outcomes compared to laser at 1 year (MD -0.22 logMAR) and 2 years (MD -0.29 logMAR) 7

Safety Profile

Anti-VEGF therapy for mCNV has a favorable safety profile with rare adverse events: 7

• Systemic serious adverse events occurred in 4.2% (15/359) of anti-VEGF treated patients versus 0% in controls (RR 4.50,95% CI 0.60 to 33.99, very low-certainty evidence) 7
• Ocular adverse events occurred in 1.4% (5/359) of anti-VEGF treated patients (RR 1.82,95% CI 0.23 to 14.71, very low-certainty evidence) 7
• No cases of endophthalmitis, retinal detachment, or mortality were reported in the included trials 7
• Patients should be counseled about endophthalmitis and retinal vasculitis risk and instructed to seek immediate care if the eye becomes red, painful, light-sensitive, or vision changes 4

Long-Term Outcomes

Early anti-VEGF treatment achieves visual improvement for up to 4 years and stabilization up to 6 years, preventing late-stage complications 1

• Visual gains are maintained with appropriate monitoring and retreatment based on disease activity 3, 1
• Continued monitoring is required to assess progression or recurrence 2

Special Considerations

Differential Diagnosis in Young Patients

In patients under 50 years with mCNV, consider alternative etiologies: 8

• Ocular histoplasmosis syndrome should be considered in young patients with monocular macular CNV 8
• Idiopathic CNV represents cases without identifiable underlying pathology and requires anti-VEGF therapy 9, 8
• Age-related macular degeneration is exceedingly rare in patients under 45 years (affects only 4.8% of white Americans aged 45+) 8
• Inflammatory conditions like multifocal choroiditis typically affect women under 50 years 8

CNV with Fibrosis

Patients with documented CNVM showing fibrosed RPE elevation require ongoing suppression to prevent vision-threatening reactivation 9

• Exam findings such as "grey-green RPE elevation now fibrosed" indicate evolution of the neovascular process requiring continued anti-VEGF treatment 9