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Anti VEGF Therapy

VEGF (vascular endothelial growth factor) is a substance that has many functions in the body. It is a provoking factor in many retinal diseases causing abnormal blood vessel development (choroidal neovascular membranes – CNVM) beneath the retina in macular degeneration and other retinal diseases, promoting leakage of retinal blood vessels causing macular edema (swelling) in diabetic retinopathy as well as retinal vein occlusions.

AntiVEGF therapy involves injection into the eye of medications that block the action of VEGF. This seals off abnormal leaky blood vessels and eliminates retinal swelling which can help recover vision in patients with diabetic macular edema, retinal edema from vein occlusions, and CNVM from age related macular degeneration as well as other causes.

There are two antiVEGF medications in Canada that are used for eye diseases. Lucentis (ranabizumab) is the only available drug of this class specifically developed and approved for use in the eye. Avastin (bevacizumab) works in the same manner as Lucentis but is not specifically approved for use in the eye. It has been approved to be used intravenously as a treatment for certain types of cancer. Retinal specialists have used avastin by injection into the eye for several years with good results and studies have shown this to have vision results similar to lucentis treatment. Delivering medication directly in to the eye allows use of very small doses and minimizes any medication effects elsewhere in the body. There is a low risk of side effects in the body with injection of these medications into the eye. It has been shown that after injection into the eye, avastin has more effect on VEGF levels in the body than lucentis and this potentially could mean increased risk. Extensive use in clinical practice has shown serious side effects to be rare.

AntiVEGF therapy is initially given as monthly injections of medication into the affected eye. A loading phase of 3 treatments on monthly interval is performed initially after which treatment is adjusted based on the response. When the eye condition is stabilized, treatment can be stopped but close ongoing monitoring is required for possible recurrence of the active eye disease. For some, ongoing treatment is needed to maintain control of the disease and the treatment interval is modified as needed to maintain control but can be as frequent as monthly.

Intravitreal injection of medications involves injection through the white of the eye (the sclera). This is a very effective way of providing medication to treat eye disease and allows use of very small doses to limit the rest of the body’s exposure to the medications. The injecton is performed with topical anesthetic (eye drops) to numb the surface of the eye. Topical antiseptic (iodine based eye drops) are applied to reduce risk of infection, an eyelid spreader is used to hold the eyelid open. The injection is brief and although there is usually some sensation, the discomfort is mild and brief. Afterwards when the numbing has worn off, the eye may feel quite irritated - (burning, gravelly sensation) for the evening after the injection and possibly still the next day – this is likely from irritation from the antiseptic. Frequent lubricating tear drops can be soothing during this time.

Infection inside the eye is a rare but potentially very serious complication of injection medication into the eye. It occurs less than 1 in 1000 injections. Progressive worsening of pain developing after treatment along with general progressive blurring of vision can be a sign of infection and this requires emergency reassessment of the eye and prompt treatment.

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