INTRAVITREAL INJECTION

Indications for Intravitreal Injections

Intravitreal injections are used for various eye conditions, including:

1. Age-related Macular Degeneration (AMD): A common cause of vision loss in older adults, particularly the wet form of AMD, where abnormal blood vessels grow under the retina and leak fluid or blood.
2. Diabetic Retinopathy: A complication of diabetes that affects the blood vessels in the retina, potentially leading to swelling and leakage.
3. Macular Edema: Swelling of the macula, often due to conditions like diabetic retinopathy, retinal vein occlusion, or post-surgical complications.
4. Retinal Vein Occlusion (RVO): A blockage of the veins in the retina, leading to fluid leakage and macular edema.
5. Uveitis: Inflammation of the uvea, which can affect the retina and cause vision problems.
6. Endophthalmitis: A severe eye infection that can cause retinal inflammation, often requiring immediate treatment.
7. Neovascular Glaucoma: A condition where new blood vessels grow in the eye, affecting drainage and intraocular pressure.

Procedure

The procedure for an intravitreal injection typically involves the following steps:

1. Preoperative Preparation:
   • Anesthesia: The eye is numbed with topical anesthetic drops to reduce discomfort.
   • Disinfection: The eye area, including the eyelids, is cleaned with antiseptic solutions to prevent infection.
   • Sterile Environment: A sterile drape is placed over the eye, and the injection site is prepared to ensure a clean, safe environment.
2. Injection:
   • A very fine needle is used to inject the medication into the vitreous body of the eye. The needle is typically inserted into the white part (sclera) of the eye, usually in the lower part of the eye, to minimize discomfort.
   • The injection itself only takes a few seconds, although the preparation time may take longer.
3. Postoperative Care:
   • After the injection, the patient may be monitored for a few minutes to check for any immediate complications, like increased intraocular pressure or signs of infection.
   • Patients are often given eye drops to help prevent infection or inflammation, and in some cases, a short course of oral antibiotics may be prescribed.
   • The eye may feel slightly irritated or gritty, and there might be some temporary blurred vision immediately following the injection.

Medications Used in Intravitreal Injections

The types of medications commonly used in intravitreal injections include:

1. Anti-VEGF (Vascular Endothelial Growth Factor) Agents:
   • Bevacizumab (Avastin): Used to inhibit abnormal blood vessel growth in conditions like wet AMD.
   • Ranibizumab (Lucentis): Similar to bevacizumab, it blocks VEGF and is commonly used for wet AMD and macular edema.
   • Aflibercept (Eylea): A newer anti-VEGF agent used to treat wet AMD, macular edema, and retinal vein occlusion.
2. Steroids:
   • Dexamethasone (Ozurdex): A corticosteroid used to treat inflammation and swelling in the eye, often used for macular edema caused by diabetic retinopathy or retinal vein occlusion.
   • Triamcinolone: Another steroid used in certain retinal conditions.
3. Antibiotics: In cases of infection, intravitreal antibiotics may be injected to treat endophthalmitis or other serious infections.
4. Gene Therapy: In some cases, new treatments involving gene therapy are being developed to treat inherited retinal diseases.

Benefits of Intravitreal Injections

• Localized Treatment: Direct delivery of the medication to the retina maximizes its effectiveness and reduces systemic side effects.
• Improved Vision: For conditions like wet AMD or diabetic macular edema, intravitreal injections can help reduce vision loss, improve visual acuity, and sometimes restore some vision.
• Minimally Invasive: The procedure is performed in a clinic, often with no need for general anesthesia, and recovery time is generally short.

Risks and Complications

While intravitreal injections are generally safe, there are some risks and potential complications, including:

1. Infection (Endophthalmitis): Although rare, an eye infection can occur. This is a serious complication and requires immediate treatment.
2. Increased Intraocular Pressure: Some patients may experience a rise in eye pressure after the injection, which can lead to glaucoma if left untreated.
3. Retinal Detachment: Though rare, there is a slight risk of retinal detachment after the procedure.
4. Bleeding: There may be minor bleeding at the injection site.
5. Cataract Formation: In some cases, especially with repeated injections, cataracts may form or worsen.
6. Vision Disturbances: Some patients may experience blurred vision or floaters temporarily after the procedure.
7. Eye Injury: The needle can potentially cause damage to the retina or other eye structures, though this is uncommon.

Post-Treatment Care

• Follow-up Appointments: After the injection, regular follow-up visits with the ophthalmologist are necessary to monitor the effectiveness of the treatment and to check for any complications.
• Use of Eye Drops: Patients are typically prescribed antibiotic or anti-inflammatory eye drops for a few days after the injection.
• Avoiding Strenuous Activity: Patients are generally advised to avoid heavy lifting or strenuous physical activity for a short period after the injection to reduce the risk of complications.

Effectiveness

The effectiveness of intravitreal injections depends on the underlying condition being treated. For example:

• In wet AMD, anti-VEGF injections can significantly slow down vision loss and, in some cases, improve vision.
• For diabetic retinopathy and macular edema, intravitreal injections can reduce swelling and improve visual acuity.
• The frequency of injections may vary, with some patients needing them every 4 to 6 weeks, depending on the condition and how well the eye responds to treatment.

Conclusion

Intravitreal injections are a crucial treatment option for a variety of retinal disorders. They offer a targeted approach to treating conditions like wet AMD, diabetic macular edema, and retinal vein occlusion, providing relief from symptoms, preserving vision, and preventing further damage. While the procedure is generally safe, it is essential for patients to work closely with their ophthalmologists to monitor for any complications and ensure the best possible outcomes.