This is an injection into the vitreous, which is the jelly-like substance inside your eye. It is performed to place medicines inside the eye near the retina.
Intravitreal injections are used to deliver drugs to the retina and other structures in the back of the eye, thus avoiding effects on the rest of the body. Common conditions treated with intravitreal injections include diabetic retinopathy, macular degeneration, retinal vascular diseases and ocular inflammation.
Once your pupils are dilated, the actual procedure may take around 10 minutes and is carried out in minor operation theatre. You will be made to lie down in a comfortable position and anaesthetic (numbing) drops will be applied in your eye. Your eye will be cleaned with an iodine antiseptic solution. A speculum is inserted and the medicine injected into the vitreous. You may experience a mild discomfort during the procedure. Antibiotic ointment will be applied and the eye padded. Antibiotic eye drops need to be instilled for a week.
The doctor will see you the next day for inflammation or increase in intraocular pressure.
Instructions following an intravitreal injection
- There are no special precautions except to avoid rubbing the eye.
- Instill the antibiotic eyedrops 4 times a day for 1 week.
- You can also take mild painkillers to alleviate any discomfort during the first few days.
Normal effects following an intravitreal injection
- A subconjunctival haemorrhage (bloodshot eye) usually occurs at the injection site. This will gradually fade within 7 to 10 days.
- Your vision may become slightly more blurred immediately after the injection. There may also be some floaters in your vision.
- You may experience mild discomfort for a few days after the injection. This discomfort should be relieved by mild painkillers.
Warning symptoms following an intravitreal injection
Although rhegmatogenous retinal detachment and cataract are potential complications of intravitreal injection, the most feared complication is endophthalmitis i.e. infection inside the eye (rates typically less than 1%).
The warning symptoms of this complication are rapid onset of:
- Increasing eye pain.
- Increasing redness of the eye.
- Greatly decreased vision.
You must contact the hospital immediately for advice if you develop these warning symptoms. It is very important to identify and treat this type of infection as quickly as possible.
Intravitreal injections for AMD, diabetic retinopathy (including macular edema) and retinal venous occlusion (RVO)
In AMD, diabetic retinopathy and retinal venous occlusion, there are increased levels of vascular endothelial growth factor (VEGF) in the eye which gives rise to new vessels and macular edema. To counteract this, an anti VEGF injection is given. The anti VEGF injections are available as Lucentis, Macugen and Avastin (off label use).
Anti VEGFs can rarely cause cerebrovascular events in the form of stroke or myocardial infarction (heart attack). Hence in patients who have a risk or history of ischemic heart disease or stroke, Macugen is preferred as it has less chance of causing such events.
These injections might have to be repeated more than once, depending upon the response of the eye.
Intravitreal triamcinolone acetonide
Triamcinolone acetonide is a long acting steroid which is given in the eye in cases of macular edema secondary to diabetes, retinal venous occlusion or uveitis (ocular inflammation).
You may feel black spots floating infront of eye, which is due to drug deposit in the vitreous. This will reduce over a period of few weeks as the drug is absorbed.
Triamcinolone may cause an increase in eye pressure (glaucoma) or cataract (clouding of the lens). The intra ocular pressure can increase in 30% people who undergo the injection. The pressure in your eyes will be checked at every visit and eye drops prescribed if the pressure increases significantly. This increase is transient, and these drops can be discontinued after some time. Cataracts are not a serious problem for the first few months after the injection, but over 50% of treated eyes will eventually develop significant cataract if triamcinolone has to be repeated.
Ozurdex intravitreal implant
This is an intravitreal steroid implant which is approved for the treatment of macular edema secodary to retinal venous occlusion. It has recently been approved by the US FDA for use in eyes with macular edema secondary to uveitis (ocular inflammation). This implant remains in the vitreous cavity for a longer duration compared to the intravitreal injections.