Intravitreal anti-VEGF injections
Intravitreal anti-VEGF injections are a treatment modality for several eye diseases involving ischaemia of the intraocular structures. This ischaemia leads to an excessive release of growth factors, the most aggressive of which is vascular endothelial growth factor – VEGF. VEGF is released by the lining (endothelium) of the retinal vessels and by the retinal pigment epithelium, and it is responsible for the formation of new, defective blood vessels in the retina and choroid as the body attempts to make up for the oxygen deficit. These defective vessels then grow into the retina, and possibly into the vitreous, and leak blood plasma proteins and lipids, or even whole blood, into these structures, thereby disabling them. These deposits can later organise into fibrotic membranes (choroidal neovascular membrane – CNV), which in the end stages turn into firm scars (disciform scars). As these diseases predominantly affect the yellow spot of the retina (the macula), the site of the sharpest (central) vision, they are devastating for the patient's sight.
Anti-VEGF agents used in ophthalmology are still under development, and two of them have emerged as the most effective and are now used worldwide:
Avastin (ranibizumab) and Lucentis (bevacizumab).
Given that Avastin is 40 times cheaper and that studies have confirmed its efficacy to be the same as that of Lucentis, Avastin is the one now widely used, including at renowned centres around the world.
It is used to treat the following eye diseases:
The injection is usually given under topical (eye-drop) anaesthesia only, under sterile conditions. It is administered into the vitreous in the outer part of the eye, through the conjunctiva and sclera, about 3–4 mm from the edge of the cornea. After the injection, the intraocular findings and intraocular pressure are checked with a special lens, and antibiotic drops must be applied to the treated eye for 3 days. Unfortunately, a single injection is usually not enough for the disease to regress, so an initial course of usually 3 injections about 6 weeks apart is necessary, followed by further injections as needed. 10% of patients are so-called non-responders, i.e. they do not respond to treatment. This procedure cannot cure the disease; it can only stabilise it or slow its progression.
Like every medical procedure, this one also carries risks of possible complications, but the incidence of the more serious ones in particular (intraocular inflammation, retinal detachment) is low. They include:
Occasional systemic adverse effects of Avastin treatment, as described in cancer patients (a rise in blood pressure, heart failure, stomach pain, pain when urinating, delayed wound healing), are rare when it is administered locally into the eye.
Intraocular injections of corticosteroid preparations (triamcinolone, Ozurdex) are not as effective as anti-VEGF agents, as this is a highly non-specific treatment.
Anti-VEGF agents used in ophthalmology are still under development, and two of them have emerged as the most effective and are now used worldwide:
Avastin (ranibizumab) and Lucentis (bevacizumab).
Given that Avastin is 40 times cheaper and that studies have confirmed its efficacy to be the same as that of Lucentis, Avastin is the one now widely used, including at renowned centres around the world.
AVASTIN (ranibizumab)
Avastin is a humanised monoclonal IgG antibody which uses its two binding sites to bind the released VEGF, thereby preventing its negative effects. It was originally used in oncology to treat cancer of the colon, lung and kidney and glioblastoma (a malignant brain tumour), at a dose of 5 mg/kg. Its use in ophthalmology was later confirmed as well. It is administered as an injection into the eye (vitreous) at a dose of 1.25 mg/0.05 ml of solution. This is a so-called off-label treatment, i.e. one not primarily intended for use in ophthalmology; however, this treatment is now routinely used worldwide.It is used to treat the following eye diseases:
- Wet age-related macular degeneration – the most common use. This treatment can also be combined with photodynamic laser therapy (PDT).
- Central retinal vein occlusion with macular involvement – can also be combined with diode or argon laser treatment.
- Diabetic macular oedema – can also be combined with diode or argon laser treatment.
- Devastating intraocular inflammation (uveitis).
- Wet myopic maculopathy (in high myopia).
- Retinopathy of prematurity (ROP) – immature retinas of premature babies. Can be combined with laser treatment or cryotherapy.
- Certain specific rare chorioretinal diseases.
The injection is usually given under topical (eye-drop) anaesthesia only, under sterile conditions. It is administered into the vitreous in the outer part of the eye, through the conjunctiva and sclera, about 3–4 mm from the edge of the cornea. After the injection, the intraocular findings and intraocular pressure are checked with a special lens, and antibiotic drops must be applied to the treated eye for 3 days. Unfortunately, a single injection is usually not enough for the disease to regress, so an initial course of usually 3 injections about 6 weeks apart is necessary, followed by further injections as needed. 10% of patients are so-called non-responders, i.e. they do not respond to treatment. This procedure cannot cure the disease; it can only stabilise it or slow its progression.
Like every medical procedure, this one also carries risks of possible complications, but the incidence of the more serious ones in particular (intraocular inflammation, retinal detachment) is low. They include:
- a rise in intraocular pressure after the injection
- eye pain
- temporary deterioration of vision
- vitreous haemorrhage
- introduction of infection into the eye
- retinal detachment.
Occasional systemic adverse effects of Avastin treatment, as described in cancer patients (a rise in blood pressure, heart failure, stomach pain, pain when urinating, delayed wound healing), are rare when it is administered locally into the eye.
Intraocular injections of corticosteroid preparations (triamcinolone, Ozurdex) are not as effective as anti-VEGF agents, as this is a highly non-specific treatment.
