Intravitreal Injection Protocol: Asepsis, Technique and Complications
Last updated: November 2026
Intravitreal injections are now the commonest procedure in many eye departments. Endophthalmitis is rare (roughly 1 in 2,000 to 5,000 injections) but devastating, and most of the protection comes from a few simple, consistent steps. This is a practical checklist for the injection room.
Before the injection
- Confirm the patient, the eye (mark it), the drug, the dose and consent.
- Check for active blepharitis, conjunctivitis, lid or lacrimal infection: postpone the injection if present.
- Measure vision and, at least at the first injection, IOP. Continue antiplatelets and anticoagulants.
- Topical anaesthetic drops, gel or a cotton bud soaked in anaesthetic.
Asepsis: the steps that matter
| Step | Evidence-based practice |
|---|---|
| Povidone-iodine 5% on the conjunctiva and lid margins | The single most important step. Apply before the speculum and again just before injecting; allow time to act. Aqueous chlorhexidine 0.05–0.1% if truly allergic to iodine. |
| Lid speculum | Keeps lashes and lid margins away from the injection site. |
| Masks and no talking | Streptococcal endophthalmitis is linked to oral flora: the injector and patient should wear masks or avoid talking. |
| Gloves | Sterile or non-sterile gloves are acceptable; hand hygiene is essential. |
| Topical antibiotics | Not recommended before or after the injection: they do not reduce endophthalmitis and promote resistant organisms. |
The injection
- Site: 3.5–4.0 mm behind the limbus in pseudophakic or aphakic eyes, 4.0 mm in phakic eyes; usually the inferotemporal quadrant.
- Needle: 30G or 32G, aimed at the centre of the globe.
- Displace the conjunctiva slightly (a tunnelled or offset entry reduces reflux).
- Inject slowly, withdraw, and press with a sterile cotton bud.
After the injection
- Check perfusion of the optic disc or hand-movement vision; check IOP if there is a risk of a sustained rise (glaucoma, large volume).
- Give clear written warning signs: increasing pain, worsening vision, increasing redness or discharge in the first week. Patients must call the same day.
- Small subconjunctival haemorrhages and a few floaters (air bubbles or drug) are normal.
Complications to recognise
| Complication | Features and action |
|---|---|
| Endophthalmitis | Pain, falling vision, hypopyon, vitritis, usually days 1–7: same-day vitreous tap and intravitreal vancomycin 1 mg and ceftazidime 2.25 mg |
| Non-infectious inflammation | Less pain, often within 24 hours, may be linked to specific drugs (for example brolucizumab-associated vasculitis): needs specialist review |
| Raised IOP | Transient after every injection; sustained rise with repeated injections, especially in glaucoma |
| Retinal tear or detachment, lens touch | Rare: check if flashes, floaters, shadow or cataract appears |
Where residents slip
- Prescribing topical antibiotics after every injection.
- Not waiting for the povidone-iodine to act.
- Talking over the open eye without a mask.
- Not giving written warning signs.
Key sources
- Avery RL, et al. Intravitreal injection technique and monitoring: updated guidelines of an expert panel. Retina. 2014;34 Suppl 12:S1-S18
- Royal College of Ophthalmologists. Ophthalmic Service Guidance: Intravitreal injection therapy. 2018
- Bhavsar AR, et al. Risk of endophthalmitis after intravitreal drug injection when topical antibiotics are not required (DRCR.net). Arch Ophthalmol. 2012;130:809-810
Related: Intravitreal drug dosages, AMD, Diabetic retinopathy, Antithrombotics and eye surgery.
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