Understanding Intravitreal Injections – A Key Treatment for Retinal Conditions
If you’ve been told you need an injection into the eye, it’s completely normal to feel anxious. Most patients tense up the moment they hear the words “intravitreal injection”, but in modern retinal care, this is one of the most routine, effective and safe treatments we perform.
As an eye specialist and eye surgeon, I regularly use intravitreal injections to treat serious retinal conditions and protect patients’ vision across Mpumalanga. This article is based on my video “Understanding Intravitreal Injections: A Key Treatment for Retinal Conditions” and explains:
- What an intravitreal injection is
- Why we need to inject medication directly into the eye
- Which conditions we treat this way
- What actually happens on the day
- Risks, warning signs and when to call your eye doctor
What is an intravitreal injection?
The name tells you exactly what it is:
- “Intra” = inside
- “Vitreous” = the clear gel that fills the back of the eye
- “Injection” = a small, controlled dose of medication with a fine needle
So, an intravitreal injection is:
A tiny injection of medication into the vitreous cavity, the gel-filled space in the back of the eye, close to the retina.
If you look at a model of the eye, most of the back chamber is filled with this clear jelly. That’s where the medicine needs to go to reach the retina and macula at effective concentrations.
Why can’t I just take tablets or ordinary eye drops?
Your body has a protective system called the blood-ocular barrier, similar to the blood–brain barrier. It:
- Protects the eye from harmful substances in the bloodstream
- But also blocks many useful medications from reaching the retina in sufficient amounts
That means:
- Tablets, ordinary eye drops or systemic medication often cannot deliver enough drug directly to the macula and retina.
- For certain retinal conditions, the only reliable way to treat the problem is to deliver the medication directly into the eye.
An intravitreal injection bypasses this barrier and delivers a precise dose of medication exactly where it’s needed.
Which conditions are treated with intravitreal injections?
Intravitreal injections are used for several sight-threatening retinal conditions. The most common include:
- Diabetic macular oedema (DME)
- Swelling in the central retina caused by diabetes
- Can cause blurred, distorted central vision
- Wet age-related macular degeneration (wet AMD)
- Abnormal, leaky new blood vessels (choroidal neovascular membrane – CNV) grow under the macula
- These vessels leak and bleed, damaging the central retina
In both of these conditions, intravitreal injections:
- Can stabilise or improve vision
- Help control leakage and swelling
- Reduce the risk of permanent central vision loss
There are different types of medications and different treatment protocols, but the principle remains the same – targeted drug delivery directly into the vitreous.
If you’re already seeing me as an eye specialist at the Lowveld Eye Institute for cataract surgery, glaucoma or other problems, intravitreal injections may be part of your retinal treatment plan if your macula is involved.
Where exactly is the injection done?
We inject through a safe zone in the white part of the eye called the pars plana:
- It sits behind the coloured iris and lens, in front of the retina
- We know the exact distance from the cornea to inject safely
- A very fine needle passes through this area into the vitreous cavity
From there, the medication can diffuse through the vitreous to reach the macula and retina.
The amount of fluid we inject is very small, just a fraction of a millilitre, but enough to be effective.
What to expect on the day – step by step
Although the thought of an injection in the eye sounds intimidating, the procedure is usually quick and surprisingly well tolerated. Many patients say the idea is far worse than the experience.
Here’s what typically happens when you come in to see your eye doctor for an intravitreal injection:
1. Numbing the eye (anaesthesia)
We make the eye as comfortable as possible:
- Anaesthetic eye drops
- Numb the surface of the eye
- Subconjunctival anaesthetic injection
- A very small amount of anaesthetic is injected just under the conjunctiva (the clear surface layer of the eye)
- Because the drops have already numbed the surface, most patients don’t feel this second injection
The goal is for the injection site to be completely numb.
2. Cleaning the eye
To minimise infection risk:
- The eye and surrounding area are cleaned with iodine solution
- The iodine is allowed to sit for a short period to disinfect the surface
This is a crucial part of making intravitreal injections as safe as possible.
3. The injection itself
- You’ll usually be asked to look down or in a particular direction
- The fine needle goes through the numb, cleaned area in the pars plana
- A small volume of medication is injected into the vitreous cavity
Most patients feel pressure at most, not sharp pain. It’s very common to hear:
“Is it done already?”
Because the injection itself is so quick.
Is an intravitreal injection painful?
With proper anaesthesia and technique, an intravitreal injection should not be painful.
You may feel:
- Mild pressure
- Slight awareness of something happening
You should not feel:
- Sharp, severe pain
- Prolonged discomfort during the injection itself
If you’re very anxious, let your eye specialist know; we can take extra steps to keep you calm and comfortable.
How safe are intravitreal injections – and what are the risks?
Intravitreal injections are now one of the most commonly performed procedures in ophthalmology worldwide. Thousands are done every day. Overall, it is a very safe procedure when performed under the correct conditions.
However, no procedure is entirely risk-free. The most important potential complication is:
Endophthalmitis, infection inside the eye
This is rare, but serious. That’s why we:
- Use iodine to disinfect the eye
- Maintain as sterile an environment as possible
- Follow strict protocols
You need to know the warning signs after an injection:
- Increasing eye pain (not just mild scratchiness)
- Decreasing or blurred vision that gets worse, not better
- Eye becoming very red
- Eyelid swelling
- Discharge from the eye
- Eye feels “full” or extremely uncomfortable
If you develop any of these symptoms in the days to two weeks after your injection:
Contact your eye specialist/eye surgeon immediately or return to the practice urgently.
Prompt treatment can make a critical difference to the final visual outcome.
Other, less serious and more common after-effects include:
- Mild scratchy feeling
- Small floater or bubble-like shadow from tiny air bubbles
- Slight redness on the white of the eye where the anaesthetic was given
These usually settle quickly.
Aftercare: what should I do at home?
After an intravitreal injection:
- You may be given drops to use for a short period
- Avoid rubbing the eye
- If vision is a bit blurred or you see small floating spots, this is often temporary
- Follow any specific instructions your eye doctor in Mbombela gives you
Most patients can go back to light activities fairly quickly, but if your vision is blurred, you should not drive until you feel safe and confident.
Final thoughts: intravitreal injections as part of your eye care
Intravitreal injections are a cornerstone treatment for serious retinal conditions such as:
- Diabetic macular oedema
- Wet age-related macular degeneration
They allow us, as eye specialists and eye surgeons, to:
- Deliver powerful medication directly where it’s needed
- Stabilise or improve vision
- Reduce the risk of long-term, irreversible central vision loss
While the idea of an injection in the eye is understandably unsettling, the procedure itself is usually quick, well-controlled and far less traumatic than patients expect.
