What are eye/intravitreal injections for?
Intravitreal injection is given into the eye near the retina. Retina is the neural layer on the back of the eye. Diabetic retinopathy and AMD (age-related macular degeneration) are two common conditions affecting the retina.
Eye drops cannot treat these conditions because the required concentration of drugs does not reach the back of the eye. For the drugs to reach the retinal layer, we need to inject them into the vitreous cavity. Vitreous fills the eye the way air fills a football. The diseased retina gets adequate concentration of the drug if we inject it into the vitreous.
The drugs used in intravitreal injections reduce the inflammation and inhibit the growth of abnormal vessels. They also reduce the swelling of the central part of retina called macula (macular edema).
What is the difference between subconjunctival and intravitreal injection?
As mentioned above, intravitreal drugs are injected into the vitreous cavity. Subconjunctival injections are given under a thin layer called conjunctiva at the surface of the eye covering the sclera (the white part of the eye).
What is an anti-VEGF agent?
VEGF stands for Vascular Endothelial Growth Factor. Anti-VEGF agents are the drugs which act against the VEGFs and inhibit the growth of the new abnormal vessels. This prevents leaking from the vessels, abnormal proliferation and scarring of retina.
Bevacizumab (Avastin) and Ranibizumab (Lucentis) are two commonly used anti-VEGF agents.
Ophthalmologists use anti-VEGF intravitreal injections for the following eye conditions:
- Wet AMD
- Diabetic macular edema (DME)
- Diabetic retinopathy with DME
- Macular edema following retinal vein occlusion (RVO)
- Any type of choroidal neovascularisation (CNV)
What is intravitreal Avastin injection for?
Avastin is the brand name of the drug Bevacizumab. It is an anti-VEGF agent which prevents the growth of abnormal and leaking vessels. Avastin is used for AMD, diabetic retinopathy and other eye conditions as mentioned in the list above.
Avastin is cheaper than Lucentis. It is given less often and has fewer systemic side effects that Lucentis.
What are the side effects of the drug Avastin?
After you receive an intravitreal injection, you may feel mild pain and redness of the eye. You may become sensitive to light for some time and may experience a foreign body sensation. You may also notice blurred vision and double vision.
In addition to the symptoms in the eye, you might feel generalized weakness, pain in abdomen and nausea.
Infection of the eye, detachment of retina and cataract is possible with all intravitreal injections. The chances of such complications are rare though.
What is Lucentis eye treatment?
Lucentis is a brand name of Ranibizumab intravitreal injection. Its chemical structure differs from that of Avastin. Lucentis is a monoclonal antibody fragment while Avastin is a complete antibody.
The cost of Lucentis injection is much more than that of Avastin.
What is eylea injection?
Eylea is a brand name of Aflibercept. Its mechanism of action is different from those of Avastin and Lucentis. It is a decoy or ‘bait’ receptor which binds with vascular endothelial growth factors with greater affinity reducing their effects significantly.
Currently, Eylea injection is not the intravitreal injection of first choice. It is used for the same eye conditions as listed above.
What is Macugen intravitreal injection?
Macugen is the brand name of Pegaptanib. It is biochemically different from Avastin and Lucentis. Although it was the first anti-VEGF treatment to get approval from FDA, it is not as frequently used as other anti-VEGF treatments.
Do injections into the eye hurt?
No. Before giving intravitreal injection, anesthetic eye drops are put in the eye to numb it so that you don’t feel any pain. After the injection, when the effect of anesthetic eye drop wears off, you may feel mild sensation which is caused by the antiseptic used to clean the eye.