How is an intravitreal anti‑VEGF injection performed, including indications, contraindications, dosage, technique, and post‑procedure care for an adult patient?

Intravitreal Anti-VEGF Injection Technique

Intravitreal anti-VEGF injections should be performed using a standardized sterile technique with topical povidone iodine antisepsis, a 30-gauge needle inserted 3.0-4.0mm posterior to the limbus through the pars plana, directed toward the optic nerve, followed by immediate assessment of central retinal artery perfusion. 1

Pre-Procedure Preparation

Patient Selection and Consent

Before proceeding, confirm the correct eye and mark it clearly. Discuss the risks with the patient, including the most serious complication—infectious endophthalmitis (occurring in approximately 0.019-0.09% of injections in clinical trials 2, though some reports suggest up to 0.05% 3). Other rare complications include retinal detachment, cataract formation, and sustained intraocular pressure elevation 4, 2.

Antisepsis Protocol (Critical for Safety)

• Apply topical anesthetic drops to the eye 1
• Place a lid speculum to ensure adequate exposure 1
• Apply topical povidone iodine directly over and surrounding the injection site 1
• Allow sufficient time for the povidone iodine to dry before proceeding 1

Important caveat: The use of topical povidone iodine is strongly recommended and considered essential—its non-use has been associated with unacceptably high endophthalmitis rates 2. In contrast, routine prophylactic topical antibiotics before or after injection are NOT recommended, as they do not reduce endophthalmitis risk 4, 2.

Injection Technique

Site Selection and Needle Insertion

• Locate the injection site 3.0-4.0mm posterior to the limbus (in phakic eyes; adjust to 3.5-4.0mm in pseudophakic eyes based on general ophthalmology principles) 1
• Prepare the proper volume of drug according to the specific anti-VEGF agent being used 1
• Use a sterile 30-gauge needle for the injection 1
• Insert the needle into the vitreous cavity via the pars plana, pointing toward the optic nerve 1

This technique minimizes the risk of lens trauma, retinal injury, and ensures proper drug delivery into the vitreous cavity.

Post-Injection Assessment

Immediate Complications Check

• Remove the lid speculum carefully, avoiding excess pressure on the eye 1
• Assess for complications immediately 1
• Confirm that the central retinal artery is perfused using either indirect ophthalmoscopy or by confirming the patient can perceive light/vision 1

This step is critical to detect acute intraocular pressure spikes that could compromise retinal perfusion.

Post-Procedure Care

• Topical antibiotics may be provided at the physician's discretion, though evidence does not support routine use 1, 2
• Patients should be instructed to report any signs of endophthalmitis immediately (pain, decreased vision, increased redness)
• Follow-up examination is typically performed at 1 month after therapy 2

Indications for Anti-VEGF Injections

The primary indications include:

• Diabetic macular edema (center-involved with vision impairment) 2, 5, 6
• Neovascular age-related macular degeneration 2
• Macular edema from retinal vein occlusion (both branch and central) 4, 7
• Proliferative diabetic retinopathy 5, 6

Contraindications

Absolute contraindications include:

• Active ocular or periocular infection
• Known hypersensitivity to the anti-VEGF agent or any component

Relative contraindications requiring careful risk-benefit assessment:

• Recent thromboembolic events (though meta-analyses show no definitive increased risk with anti-VEGF therapy 2)
• Uncontrolled glaucoma
• Pregnancy (retinopathy may worsen during pregnancy, but treatment decisions must be individualized 5, 6)

Dosing by Agent

Standard doses for FDA-approved agents:

• Ranibizumab (Lucentis): 0.3-0.5mg 4, 5, 6
• Aflibercept: 2mg 4, 5, 6
• Bevacizumab (Avastin): Off-label use, typically 1.25mg (though not FDA-approved for intraocular use, it has demonstrated comparable efficacy in multiple studies 2)

Treatment Frequency

Initial treatment typically follows monthly injections for the loading phase, then transitions to as-needed (PRN) or treat-and-extend regimens based on disease response 4, 2. The specific protocol depends on the underlying condition and individual response, with OCT and visual acuity guiding retreatment decisions.

Common pitfall: Delayed treatment can result in suboptimal visual outcomes. Studies demonstrate that eyes receiving immediate anti-VEGF therapy achieve better visual results than those with delayed treatment 7.