Bevacizumab in Eye Disease vs Cancer: — Same Drug, Very Different Dose

Both conditions can involve abnormal blood vessel growth driven by the same protein, called VEGF. In cancer, tumours release VEGF to build their own blood supply. In certain eye conditions — such as wet age-related macular degeneration and diabetic macular edema — VEGF causes blood vessels to leak or grow abnormally under the retina.

Bevacizumab blocks VEGF in both settings. Because the conditions are in completely different parts of the body, the way the drug is delivered is completely different.

Same drug, same mechanism — but the dose, the route, the specialist managing your treatment, and the side effects you need to watch for are all different depending on which condition is being treated.

For conditions such as wet age-related macular degeneration, diabetic macular edema, and retinal vein occlusion, bevacizumab is injected directly into the eye by an ophthalmologist. The dose is very small compared to cancer treatment.

Because the drug stays within the eye, it does not cause the whole-body side effects associated with the cancer infusion. After an injection you may notice temporary blurring, mild discomfort, or a feeling of pressure. These usually settle within a day.

One side effect that needs urgent attention: if your eye becomes increasingly red, painful, or blurred in the days after an injection, contact your ophthalmologist the same day. This can be a sign of infection inside the eye and needs prompt treatment.

Your ophthalmologist will schedule follow-up visits to decide whether further injections are needed based on how your eye is responding.

For cancer, bevacizumab is given as an intravenous infusion — a drip through a vein — usually alongside chemotherapy. The dose is far larger than the eye injection and circulates through the whole body. At CION, it is given as day care.

It is used in several cancer types, including colorectal cancer, certain lung cancers, ovarian and cervical cancers, and glioblastoma, among others. Your oncologist will explain why it has been chosen for your specific diagnosis.

Because it works throughout the body, its side effects differ from those of the eye injection. Raised blood pressure and protein in the urine are among the more common ones, and your team will monitor both at each visit. Wound healing is slower on bevacizumab, so it is usually paused before planned surgery.

Tell your team immediately if you develop a sudden severe headache, chest pain, breathlessness, leg swelling, or any unusual bleeding. These are not common, but they need same-day assessment.