Ranibizumab

Ranibizumab is an antibody fragment directed at Vascular endothelial growth factor A (VEGF-A), given by intravitreal injection for retinal disease driven by pathological neovascularization and vascular leakage. It is a Fab rather than a whole antibody, and the missing Fc region is the design: without it the molecule is smaller, penetrates the retina readily, and is cleared from the systemic circulation quickly once it leaves the eye, limiting suppression of VEGF elsewhere in the body. It shares a parent antibody with bevacizumab, which is used off-label for the same indications at a fraction of the cost — a comparison settled by head-to-head trials showing similar visual outcomes, and one that continues to shape practice worldwide.

Blocking VEGF-A removes the principal driver of both new vessel growth and the vascular permeability that produces macular oedema. That accounts for its use in neovascular Age-related macular degeneration, myopic choroidal neovascularization, Diabetic macular oedema, diabetic retinopathy and macular oedema following retinal vein occlusion. It is not standard Therapy in central serous chorioretinopathy, where the underlying process is choroidal rather than VEGF-driven, unless secondary choroidal neovascularization has developed.

The practical constraints are the injections themselves. Effect duration is short, so treatment began as monthly dosing and has moved to treat-and-extend regimens that individualize the interval, with longer-acting agents such as aflibercept and faricimab and a refillable port delivery implant developed to reduce the burden. Each injection carries a small risk of endophthalmitis, retinal detachment and intraocular pressure rise, and biosimilars have entered the market as patents expired. Current research concerns variability in response between patients, long-term outcomes over years of repeated treatment, and intraocular pharmacokinetics — how long a given dose actually suppresses VEGF within the eye.