Managing Complications After Intravitreal Injections: A Surgeon’s Handbook

Indications for Intravitreal Injection

Intravitreal injections are a cornerstone treatment for various retinal and vitreous diseases. The primary indications include:

1. Age-Related Macular Degeneration (AMD): Both wet (neovascular) and dry forms, with a focus on anti-VEGF (vascular endothelial growth factor) therapy for the wet form.
2. Diabetic Retinopathy: Particularly diabetic macular edema (DME), which is a common complication of diabetes, leading to vision loss.
3. Retinal Vein Occlusion (RVO): Includes both branch and central RVO, where macular edema is a key cause of visual impairment.
4. Endophthalmitis: An emergency situation where antibiotics or antifungals are delivered directly into the vitreous cavity.
5. Uveitis: In cases of posterior uveitis, intravitreal injections of corticosteroids or immunosuppressants may be indicated.
6. Retinal Detachment Adjunct Therapy: As part of a broader treatment plan, often involving silicone oil or gas tamponade.
7. Intraocular Tumors: For delivering chemotherapeutic agents directly to the site of tumors, such as retinoblastoma.

Preoperative Evaluation

Before performing an intravitreal injection, a thorough preoperative evaluation is crucial to optimize outcomes and minimize complications. Key elements include:

1. Detailed Ophthalmic Examination: Assessment of visual acuity, intraocular pressure, slit-lamp examination, and fundus examination using ophthalmoscopy and optical coherence tomography (OCT).
2. Medical History Review: Identifying systemic conditions such as diabetes, hypertension, and coagulation disorders that might influence the injection procedure or healing process.
3. Imaging Studies: OCT and fluorescein angiography help assess the extent of retinal disease, monitor fluid levels, and guide the choice of therapeutic agents.
4. Informed Consent: The patient should be fully informed about the procedure, potential risks, and alternative treatments. This discussion should be documented, emphasizing the importance of follow-up care.

Contraindications

While intravitreal injections are generally safe, certain contraindications must be considered:

1. Active Ocular Infection: Conjunctivitis, blepharitis, or any other ocular infection should be treated before proceeding with the injection to prevent endophthalmitis.
2. Severe Ocular Surface Disease: Conditions like severe dry eye or corneal ulcers may exacerbate following the injection.
3. Hypersensitivity to Medication: Patients with known allergies to the medication to be injected (e.g., anti-VEGF agents, corticosteroids) should be considered for alternative treatments.
4. Uncontrolled Systemic Disease: Conditions such as uncontrolled diabetes or hypertension may require stabilization before the injection.

Surgical Techniques and Steps

Intravitreal injections are performed in a controlled, sterile environment, typically in an outpatient setting. The key steps are:

1. Preparation: Ensure a sterile field with proper draping. Povidone-iodine solution is applied to the ocular surface and periocular skin to reduce the risk of infection.
2. Anesthesia: Topical anesthesia, such as proparacaine drops, is commonly used. In some cases, a subconjunctival injection of lidocaine may be administered for additional comfort.
3. Injection Site: The injection is typically administered through the pars plana, located 3.5 to 4.0 mm posterior to the limbus. The exact site is marked, and a speculum is used to keep the eyelids open.
4. Injection: A 30-gauge needle is commonly used for the injection. The needle is introduced into the vitreous cavity at a perpendicular angle, and the medication is slowly injected. The volume injected is usually 0.05 to 0.1 ml.
5. Post-Injection Procedures: After the injection, the needle is withdrawn, and a cotton-tipped applicator is used to apply gentle pressure to the injection site to prevent reflux. The eye is then washed with saline, and antibiotic drops are instilled.

Postoperative Care

Postoperative care is essential to monitor the patient for any adverse effects and to ensure optimal healing. Recommendations include:

1. Antibiotic Prophylaxis: Topical antibiotics are often prescribed for 3 to 7 days post-injection to prevent infection.
2. Monitoring Intraocular Pressure (IOP): The IOP should be measured immediately after the injection and monitored during follow-up visits, especially if a significant volume of medication was injected.
3. Patient Instructions: Patients should be instructed to report any symptoms of pain, decreased vision, redness, or discharge immediately, as these may be signs of complications such as endophthalmitis.
4. Follow-Up: A follow-up appointment is usually scheduled within 1-2 weeks post-injection to assess the response to treatment and plan further management.

Possible Complications

Although intravitreal injections are generally safe, several potential complications should be considered:

1. Endophthalmitis: A rare but severe infection of the intraocular cavity that requires immediate intervention with intravitreal antibiotics or antifungals.
2. Retinal Detachment: The injection can occasionally cause a retinal tear, leading to detachment.
3. Vitreous Hemorrhage: The injection may cause bleeding into the vitreous cavity, particularly in patients with proliferative diabetic retinopathy.
4. Increased Intraocular Pressure: A transient rise in IOP is common, but in some cases, it may be prolonged and require treatment.
5. Lens Injury: Inadvertent needle contact with the crystalline lens can lead to cataract formation.
6. Allergic Reactions: Though rare, hypersensitivity reactions to the injected drug can occur.

Different Techniques

Intravitreal injections may vary slightly depending on the drug being administered and the specific condition being treated:

1. Anti-VEGF Injections: Used primarily for AMD, DME, and RVO, these injections include agents such as ranibizumab, bevacizumab, and aflibercept. Multiple injections are often required, with dosing intervals ranging from monthly to every few months.
2. Corticosteroid Injections: Triamcinolone acetonide and dexamethasone implants are used for treating macular edema and uveitis. These may have a longer duration of action but also carry a higher risk of increased IOP and cataract formation.
3. Antibiotic/Antifungal Injections: These are used in cases of endophthalmitis and may require repeated dosing depending on the severity of the infection.
4. Chemotherapy Injections: Used for intraocular tumors, the technique may involve localized delivery of drugs like melphalan, often combined with systemic chemotherapy.

Prognosis and Outcome

The prognosis following intravitreal injection varies depending on the underlying condition:

1. Age-Related Macular Degeneration: Anti-VEGF therapy has revolutionized the treatment of wet AMD, with many patients experiencing stabilization or even improvement in vision.
2. Diabetic Macular Edema: Intravitreal injections can significantly reduce macular thickness and improve visual acuity, particularly with anti-VEGF agents.
3. Retinal Vein Occlusion: Early treatment with intravitreal injections can lead to substantial improvement in vision, although some patients may require long-term therapy.
4. Endophthalmitis: Prompt treatment with intravitreal antibiotics can save vision, but the prognosis depends on the severity and rapidity of treatment.

Alternative Options

For some patients, alternative treatments may be considered:

1. Laser Therapy: In cases of diabetic retinopathy and certain forms of AMD, laser photocoagulation may be used instead of or in conjunction with intravitreal injections.
2. Systemic Therapy: For conditions like uveitis or intraocular tumors, systemic immunosuppressants or chemotherapy may be preferred, especially when bilateral involvement or extraocular spread is a concern.
3. Surgery: In cases of retinal detachment or persistent vitreous hemorrhage, vitrectomy surgery may be necessary.

Average Cost

The cost of intravitreal injections can vary widely depending on the drug used, geographic location, and healthcare setting. On average:

1. Anti-VEGF Injections: These can range from $1,500 to $2,000 per injection, with some patients requiring multiple injections over time.
2. Corticosteroid Implants: These may cost between $1,000 and $1,500 per injection, with the added cost of follow-up for potential complications.
3. Antibiotic/Antifungal Injections: The cost can vary based on the drug and the need for repeated dosing but generally ranges from $500 to $1,500.

Recent Advances

Recent advancements in intravitreal injection techniques and therapies have improved outcomes and expanded the range of treatable conditions:

1. Long-Acting Implants: The development of longer-acting implants, such as brolucizumab, reduces the need for frequent injections, improving patient compliance.
2. Gene Therapy: Emerging gene therapies for inherited retinal diseases may involve intravitreal delivery, offering hope for conditions previously considered untreatable.
3. New Anti-VEGF Agents: Agents like faricimab are being developed, which may offer better efficacy and durability than current treatments.
4. Biosimilars: The introduction of biosimilar anti-VEGF agents may reduce the cost of treatment, making it more accessible to a broader population.

Best Practices

Surgeons performing intravitreal injections should adhere to best practices to ensure optimal outcomes:

1. Sterility: Strict aseptic techniques are essential to minimize the risk of endophthalmitis.
2. Patient Selection: Careful patient selection and thorough preoperative evaluation can reduce the risk of complications and improve treatment outcomes.
3. Follow-Up: Regular follow-up and monitoring are crucial, particularly in patients receiving multiple injections over time.
4. Education: Educating patients about the importance of adherence to treatment and follow-up can improve long-term outcomes.
5. Documentation: Detailed documentation of each injection, including the drug used, dose, injection site, and any immediate complications, is essential for ongoing patient care and medico-legal reasons.