Retina — a mastered technical procedure

Understand it visually

Intravitreal injection (anti-VEGF): how it works

The injection is performed in the office, under local anaesthesia with eye drops, using a very fine needle passing through the pars plana. The drug diffuses into the vitreous up to the macula, where it causes the abnormal vessels to regress and the oedema to resolve.

Intravitreal injections: indications and protocol

Over the past fifteen years or so, intravitreal injections have become the standard treatment for most vascular and neovascular retinal diseases. An overview of the indications, the molecules used in the office, the protocol in a dedicated room, and the safety landmarks.

What is an intravitreal injection?

An intravitreal injection (IVI) consists of administering a drug directly into the vitreous cavity, the space located between the lens and the retina. It is performed through the pars plana, 3.5 to 4 millimetres from the corneal limbus in the phakic patient, or 3 to 3.5 millimetres in the pseudophakic patient, under sterile conditions and topical anaesthesia with eye drops.

The benefit of this route of administration is twofold: delivering a high and lasting dose of drug in direct contact with the retina, while limiting systemic exposure. It has revolutionised the management of exudative AMD, diabetic macular oedema and retinal vein occlusions since the introduction of the first ophthalmic anti-VEGF in 2006.

The intravitreal injection, step by step

A quick procedure, performed in a dedicated room under local anaesthesia with eye drops.

macula 3.5 – 4 mm (pars plana)
  1. 1

    Preparation and antisepsis

    The eye and its surroundings are disinfected, a small speculum holds the eyelids open, and an anaesthetic drop ensures comfort during the procedure.

  2. 2

    Locating the entry point

    The entry point is measured 3.5–4 mm behind the edge of the cornea (the “pars plana”): a safe zone, away from the lens and the retina.

  3. 3

    Injection into the vitreous

    ⏱ a few seconds

    A very fine needle passes through the wall and deposits the drug into the gel that fills the eye (the vitreous).

  4. 4

    Drug diffusion

    The product diffuses into the vitreous and acts in contact with the retina — for example to dry out abnormal vessels (wet AMD, retinal oedema).

Main indications

IVIs are offered after a complete ophthalmological assessment combining fundus examination, optical coherence tomography (OCT) and, depending on the case, OCT-angiography or fluorescein angiography. The indication is confirmed on the basis of clinical and imaging criteria.

1. Exudative AMD (wet form)

The exudative form of age-related macular degeneration is characterised by the development of choroidal neovessels that leak fluid and blood beneath the macula. Without treatment, the course can rapidly lead to a fibrous scar and a severe loss of central vision. Anti-VEGF agents have transformed the prognosis: the majority of patients treated early maintain or improve their visual acuity in the medium and long term. The earliness of treatment directly determines the visual outcome.

2. Diabetic macular oedema (DMO)

Macular oedema is the leading cause of visual loss in the diabetic patient. It corresponds to an accumulation of fluid in the macula secondary to a breakdown of the blood-retinal barrier. The standard treatment relies on anti-VEGF agents as first-line therapy, with optimised glycaemic and blood-pressure control in parallel.

In case of insufficient response or contraindication to anti-VEGF agents, intravitreal corticosteroids (Ozurdex, Iluvien) provide an effective alternative, particularly in pseudophakic patients. This management fits into the overall care pathway of diabetic retinopathy, closely followed up at the Paris 13 office.

3. Retinal vein occlusion (RVO)

Retinal vein occlusions — of the central vein (CRVO) or of a branch vein (BRVO) — cause macular oedema and sometimes retinal ischaemia. Management combines anti-VEGF agents as first-line therapy to rapidly reduce the oedema, close monitoring of capillary perfusion with OCT-angiography or fluorescein angiography, and systematic screening for neovascularisation of the anterior segment, which requires appropriate laser treatment. Intravitreal corticosteroids can complement the therapeutic arsenal in certain resistant forms.

4. Post-surgical macular oedema (Irvine-Gass syndrome)

This is an inflammatory cystoid macular oedema occurring in the weeks to months following lens surgery, most often cataract surgery. Treatment combines topical anti-inflammatory agents (NSAIDs and corticosteroid eye drops) as first line. In case of persistence, a dexamethasone implant (Ozurdex) allows rapid and durable resolution of the oedema in the vast majority of cases.

5. Choroidal neovessels in high myopia

The highly myopic patient (axial length greater than 26.5 mm or myopia greater than -6 dioptres) has an increased risk of macular choroidal neovascularisation, often small in size but with a strong scarring potential. Anti-VEGF agents used in a “pro re nata” (PRN) mode guided by OCT and angiography make it possible to stabilise the lesion. Monitoring is then continued over the long term, as the risk of late recurrence is far from negligible in these patients.

The molecules used in the office

Anti-VEGF

Anti-VEGF agents block the vascular endothelial growth factor, the main signal for the formation and permeability of retinal and choroidal neovessels. Three molecules are used in the office, depending on the patient’s profile, the disease and the therapeutic response.

  • Aflibercept 8 mg (Eylea HD) — high-dose formulation of aflibercept, approved in Europe in 2024. Its pharmacokinetic profile allows, in a significant proportion of cases, the injections to be spaced out up to 12 to 16 weeks after the induction phase. The PULSAR study (Lanzetta et al., Lancet, 2024) demonstrated non-inferiority in AMD; the PHOTON study (Brown et al., Lancet, 2024) in diabetic macular oedema.
  • Faricimab (Vabysmo) — bispecific antibody simultaneously inhibiting VEGF-A and angiopoietin-2. The TENAYA/LUCERNE studies (Heier et al., Lancet, 2022) in AMD and YOSEMITE/RHINE (Wykoff et al., Lancet, 2022) in DMO showed injection intervals extended up to 16 weeks in a proportion of patients, with a visual outcome comparable to aflibercept 2 mg every 8 weeks.
  • Ranibizumab (Lucentis) — anti-VEGF-A, a pioneer of the modern management of neovascular retinal diseases, still used in certain indications depending on the patient’s profile and updated guidelines.

Bevacizumab (Avastin), used off-label in certain hospital centres, is not included in my protocol in private practice.

Intravitreal corticosteroids

Intravitreal corticosteroids are mainly used in macular oedema (diabetic, venous or post-surgical), as an alternative or complement to anti-VEGF agents. Two implants are available in the office:

  • Ozurdex (dexamethasone 0.7 mg) — biodegradable sustained-release implant, active for 3 to 6 months on average. The MEAD study (Boyer et al., Ophthalmology, 2014) demonstrated its efficacy in diabetic macular oedema over a 3-year follow-up, with around 20% of patients gaining 15 ETDRS letters. Also indicated in RVO, Irvine-Gass and certain uveitis.
  • Iluvien (fluocinolone acetonide 0.19 mg) — non-biodegradable implant releasing the active ingredient for about 36 months. The FAME study (Campochiaro et al., Ophthalmology, 2012) demonstrated a durable visual benefit in chronic DMO with insufficient response to other treatments. Reserved for pseudophakic patients with no history of significant intraocular pressure elevation under corticosteroids.

Corticosteroids carry two main side effects: corticosteroid-induced ocular hypertension (monitored every month) and, in the phakic patient, an accelerated cataract. This last point explains why Iluvien is reserved for patients who have already had cataract surgery.

Treatment regimen: induction then treat-and-extend

Anti-VEGF treatment classically begins with an induction phase, consisting of three closely spaced monthly injections, designed to rapidly dry out the active lesion. Beyond that, the strategy followed is the treat-and-extend (T&E) approach: the interval between two injections is adjusted according to the activity observed on OCT at each check-up. With a dry retina, the interval is gradually extended; in case of recurrence, it is shortened.

The aim is to maintain a fluid-free retina with the minimum number of injections, to preserve vision and limit the treatment burden for the patient and their relatives. Recent molecules (Eylea HD, Vabysmo) make it possible, in a proportion of patients, to reach intervals of up to 12 to 16 weeks.

Performed in a dedicated room

I perform intravitreal injections in a dedicated room in Cachan and Paris 13, in accordance with the recommendations of the French Society of Ophthalmology and the HAS. The typical sequence:

  • Welcome in the dedicated room, positioning in the supine position.
  • Instillation of anaesthetic eye drops (tetracaine or oxybuprocaine).
  • Cutaneous-conjunctival disinfection with povidone iodine (Bétadine 5%), with the contact time observed.
  • Placement of the sterile drape and the lid speculum.
  • Injection with a 30 G needle, through the pars plana, 3.5-4 mm from the corneal limbus in the phakic patient, 3-3.5 mm in the pseudophakic patient.
  • Verification of light perception immediately after the injection.
  • Gentle rinsing, no occlusive dressing, return home a few minutes later.

The procedure itself lasts a few seconds; the whole session, including preparation and disinfection, takes 10 to 15 minutes. Pain is very mild thanks to topical anaesthesia; most patients describe a brief pressure, without real pain.

Tolerance and safety

IVIs are today among the most frequently performed procedures in ophthalmology, with a well-established safety profile. The adverse effects fall into three categories:

  • Common and benign — a foreign-body sensation for 24 to 48 hours, small subconjunctival haemorrhages of no consequence, transient watering. Driving is not recommended in the hours that follow if vision is blurred.
  • To be monitored — transient elevation of intraocular pressure (especially after corticosteroids), floaters for a few days, rare sterile intraocular inflammation.
  • Rare but serious — endophthalmitis (intraocular infection), whose rate under modern conditions is on the order of 1 per 3,000 to 5,000 injections, retinal detachment, significant intravitreal haemorrhage, traumatic cataract (exceptional).

Warning signs to be aware of after an injection: unusual or progressive ocular pain, marked redness, sudden visual loss, intense photophobia. Their appearance in the days that follow requires an emergency consultation to rule out endophthalmitis, the prognosis of which depends directly on the earliness of diagnosis.

Dr Tourabaly’s view

“Intravitreal injections are a routine procedure for the surgeon, but rarely for the patient — who often approaches the first injection with a great deal of apprehension. My role is to place the procedure back in its context: a codified, quick, well-tolerated procedure, whose regularity is the real key to the visual outcome. Having a dedicated room in both offices and a strict aseptic protocol makes it possible to deliver these treatments under the best conditions, without the patient having to travel to a clinic for each injection.”

Patient pathway

  • Cachan office (94) — consultations, OCT Cirrus 6000, intravitreal injections in a dedicated room. Telephone: 01 45 47 08 11.
  • Paris 13 office — Diabet’ — consultations, swept-source OCT TowardPi YAlkaid with ultra-wide-field OCT-angiography, intravitreal injections in a dedicated room. Telephone: 01 89 31 30 60.

Consultation appointments can be booked directly on Doctolib. For patients already being followed, injections are scheduled in advance according to the treat-and-extend regimen. The first check-ups after initiation are close together (1 month), then gradually spaced out depending on the course.

Frequently asked questions

The number of injections depends on the disease, the molecule used and the individual response. As an order of magnitude: 6 to 8 injections in the first year for exudative AMD, often fewer thereafter; 5 to 7 injections per year on average for diabetic macular oedema. Recent molecules (Eylea HD, Vabysmo) make it possible, in a proportion of patients, to reach 3 to 4 injections per year after the first year, which significantly reduces the treatment burden.

Pain is very mild thanks to topical anaesthesia. Most patients describe a brief pressure, a short sensation, often less intense than anticipated before the first injection. A foreign-body sensation within 24 to 48 hours and a slightly reddened eye are possible but harmless. A significant pain, a visual loss or marked redness in the days that follow should, however, lead to an emergency consultation.

It is preferable not to drive immediately after an injection, as vision may remain blurred for a few hours due to the residual povidone iodine and the anaesthesia. Arranging for someone to accompany you or a journey by transport for the first injection is a good rule. Subsequent injections are often better anticipated in terms of personal organisation.

A change (switch) may be proposed in case of partial response, an injection interval that cannot be extended beyond a few weeks, or adverse effects. Switching from one anti-VEGF to another — or to an intravitreal corticosteroid in certain indications — can sometimes unlock a therapeutic situation. This decision is made in consultation on precise OCT and clinical-course criteria.

The regularity of the treatment is essential: each week of delay can allow neovascular activity to reappear and compromise the visual gain achieved. In case you are prevented from attending, it is imperative to contact the office as soon as possible to reschedule within the shortest possible timeframe. A delay of a few days is of no consequence; a postponement of several weeks may require resuming the intensive regimen.

For the majority of current indications (exudative AMD, DMO, RVO), intravitreal injections are the standard treatment validated by international studies and guidelines. Laser still has a place in certain situations (ischaemic RVO, certain focal DMO, iris neovascularisation). Photodynamic therapy (PDT) remains indicated in specific forms such as polypoidal vasculopathy. The alternative to treatment is monitoring without treatment — an option which, in exudative AMD for example, leads to progressive visual loss and is therefore rarely chosen.

Book an appointment for a retina assessment

Appointment in Cachan
Appointment in Paris 13

Sources

  1. Heier JS, Khanani AM, Quezada Ruiz C, et al. Efficacy, durability, and safety of intravitreal faricimab up to every 16 weeks for neovascular age-related macular degeneration (TENAYA and LUCERNE): two randomised, double-masked, phase 3, non-inferiority trials. Lancet. 2022;399(10326):729-740. PMID: 35085502
  2. Lanzetta P, Korobelnik JF, Heier JS, et al. Intravitreal aflibercept 8 mg in neovascular age-related macular degeneration (PULSAR): 48-week results from a randomised, double-masked, non-inferiority, phase 3 trial. Lancet. 2024;403(10432):1141-1152. PMID: 38461841
  3. Wykoff CC, Abreu F, Adamis AP, et al. Efficacy, durability, and safety of intravitreal faricimab with extended dosing up to every 16 weeks in patients with diabetic macular oedema (YOSEMITE and RHINE): two randomised, double-masked, phase 3 trials. Lancet. 2022;399(10326):741-755. PMID: 35085503
  4. Brown DM, Boyer DS, Do DV, et al. Intravitreal aflibercept 8 mg in diabetic macular oedema (PHOTON): 48-week results from a randomised, double-masked, non-inferiority, phase 2/3 trial. Lancet. 2024;403(10432):1153-1163. PMID: 38461843
  5. Korobelnik JF, Holz FG, Roider J, et al. Intravitreal Aflibercept Injection for Macular Edema Resulting from Central Retinal Vein Occlusion: One-Year Results of the Phase 3 GALILEO Study. Ophthalmology. 2014;121(1):202-208. PMID: 24084497
  6. Boyer DS, Yoon YH, Belfort R Jr, et al. Three-year, randomized, sham-controlled trial of dexamethasone intravitreal implant in patients with diabetic macular edema (MEAD Study). Ophthalmology. 2014;121(10):1904-1914. PMID: 24907062
  7. Campochiaro PA, Brown DM, Pearson A, et al. Sustained delivery fluocinolone acetonide vitreous inserts provide benefit for at least 3 years in patients with diabetic macular edema (FAME Study). Ophthalmology. 2012;119(10):2125-2132. PMID: 22727177

This article is for informational purposes. A personalised ophthalmological opinion remains essential for any therapeutic decision.