Anti-VEGF Therapy for Wet AMD: Ranibizumab, Aflibercept, Faricimab & OCT Fluid
The Angiogenic Storm: Choroidal Neovascularization (CNV)
When soft drusen and Bruch's membrane calcification starve the retinal pigment epithelium of oxygen, ischemic RPE cells secrete massive quantities of Vascular Endothelial Growth Factor A (VEGF-A).
VEGF-A binds to VEGFR-2 receptor tyrosine kinases on choroidal endothelial cells, stimulating Choroidal Neovascularization (CNV):
These fragile, immature vessels lack tight zonula occludens junctions. They leak serum, lipids, and blood directly into the sub-retinal and intra-retinal space, physically detaching photoreceptors from their nourishing base.
The Molecular Inhibitors: Ranibizumab to Faricimab
Intravitreal anti-VEGF agents neutralize this angiogenic cascade:
- Ranibizumab (Lucentis, 48 kDa Fab fragment): Binds all active isoforms of VEGF-A with high affinity.
- Aflibercept (Eylea, 115 kDa recombinant fusion decoy protein): Combines binding domains of VEGFR-1 and VEGFR-2 fused to human IgG1 Fc, delivering a 100-fold higher binding affinity than ranibizumab and binding Placental Growth Factor (PlGF).
- Faricimab (Vabysmo, 150 kDa Bispecific Antibody): The newest breakthrough—simultaneously neutralizing VEGF-A and Angiopoietin-2 (Ang-2). Inhibiting Ang-2 restores vascular stability, enabling injection intervals to extend safely up to 16 weeks!
OCT Metrology: Monitoring IRF, SRF, and SHRM
On monthly SD-OCT scans, retinal specialists guide treatment by tracking fluid compartments:
- Intraretinal Fluid (IRF): Cystoid spaces within retinal layers; highly neurotoxic to photoreceptors; must be completely dried.
- Subretinal Fluid (SRF): Fluid pooled between photoreceptor outer segments and RPE; moderate tolerance under treat-and-extend protocols.
- Subretinal Hyperreflective Material (SHRM): Precursor to fibrous disciform scarring; requires aggressive anti-VEGF suppression.
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