What are the eye injections for cystoid macular edema?

October 10, 2025 •

4 min read

Cystoid macular edema (CME) after cataract surgery can occur in up to 70% of cases, though most resolve without intervention [1.3.5]. For those who need treatment, an important question is: what are the eye injections for cystoid macular edema?

Quick Summary

The main treatments for cystoid macular edema involve intravitreal injections of anti-VEGF medications or corticosteroids [1.2.1]. These drugs reduce swelling and leakage in the macula to preserve and restore vision.

Key Points

Primary Treatments: Eye injections for cystoid macular edema (CME) primarily involve two classes of drugs: anti-VEGF agents and corticosteroids [1.2.1].
Anti-VEGF Mechanism: Anti-VEGF medications like Avastin, Lucentis, and Eylea work by blocking a protein that causes blood vessels to leak fluid into the macula [1.2.4].
Corticosteroid Role: Corticosteroids, administered as injections (Triamcinolone) or sustained-release implants (Ozurdex, Iluvien), reduce inflammation and swelling [1.2.4, 1.6.1, 1.6.2].
Procedure Simplicity: The injection is a quick, in-office procedure where medication is delivered into the eye's vitreous with a tiny needle after numbing [1.10.2].
Common Causes of CME: CME is often caused by inflammation following eye surgery, diabetic retinopathy, or retinal vein occlusions [1.8.3].
Treatment Goal: The goal of these injections is to reduce macular swelling, thereby preserving and often improving sharp, central vision [1.2.1].
Side Effect Differences: While all injections carry a small risk of infection, corticosteroids also have a known risk of causing cataracts and increased eye pressure [1.2.1, 1.7.1].

Understanding Cystoid Macular Edema (CME)

Cystoid macular edema (CME) is a painless condition where fluid accumulates in the macula, the part of the retina responsible for sharp, central vision [1.7.4, 1.8.2]. This fluid collection occurs in cyst-like patterns, leading to swelling that distorts and blurs central vision [1.8.1]. While peripheral vision is usually unaffected, CME can significantly impact detailed tasks like reading and driving [1.8.1].

CME can result from various conditions, including diabetic retinopathy, retinal vein occlusion, and uveitis [1.8.3]. It is also a common complication following eye surgery, particularly cataract surgery [1.8.1]. The underlying cause is often inflammation, which disrupts the blood-retinal barrier, causing blood vessels to leak fluid into the macula [1.8.1, 1.8.2].

Intravitreal Injections: The Primary Treatment

For persistent or severe CME, the most common and effective treatments are medications delivered directly into the vitreous—the jelly-like substance that fills the eye [1.10.2]. This procedure, known as an intravitreal injection, allows the drug to act directly on the retina [1.10.3]. The two main classes of drugs administered via injection for CME are anti-VEGF agents and corticosteroids [1.2.1].

Anti-VEGF Injections

Anti-vascular endothelial growth factor (anti-VEGF) therapy is a cornerstone treatment for various retinal conditions, including CME [1.5.1]. In many eye diseases, the body overproduces a protein called VEGF, which makes blood vessels weak and leaky [1.2.4]. Anti-VEGF medications work by blocking this protein, which helps to stop leakage, reduce swelling in the macula, and improve vision [1.2.4].

Commonly used anti-VEGF drugs include:

Avastin (bevacizumab): Originally developed as a cancer treatment, Avastin is widely used "off-label" to effectively treat retinal swelling. Studies have shown it is safe and effective for conditions like CME [1.2.1, 1.5.2].
Lucentis (ranibizumab): This drug was specifically designed for use in the eye and is FDA-approved to treat macular edema from various causes [1.2.1]. It blocks VEGF to prevent abnormal blood vessel growth and leakage [1.2.1].
Eylea (aflibercept): Eylea and its higher-dose version, Eylea HD, are also FDA-approved for treating diabetic macular edema and other related conditions [1.2.1].
Vabysmo (faricimab-svoa): As the newest medication in this class, Vabysmo targets both VEGF and another protein called angiopoietin-2 (Ang-2), which also contributes to vascular leakage [1.2.1]. This dual-action can be highly effective.

Typically, patients may need injections every four to twelve weeks, depending on the specific drug and their individual response [1.5.3].

Corticosteroid Injections and Implants

Corticosteroids are powerful anti-inflammatory agents that can effectively reduce macular swelling [1.2.4]. They work by inhibiting inflammatory pathways, thus strengthening the blood-retinal barrier and reducing fluid leakage [1.2.2]. For CME, steroids can be administered as direct injections or as long-acting implants.

Key corticosteroid treatments include:

Triamcinolone Acetonide (Triesence, Kenalog): This steroid can be injected directly into the vitreous to treat macular edema from conditions like diabetes, retinal vein occlusion, and uveitis [1.2.1, 1.2.4]. Its effect typically lasts for a few months [1.2.2].
Ozurdex (dexamethasone intravitreal implant): This is a biodegradable implant injected into the eye in an office procedure [1.2.1]. It slowly releases the steroid dexamethasone over several months to treat macular edema and inflammation [1.6.1].
Iluvien (fluocinolone acetonide intravitreal implant): This is a tiny, non-biodegradable implant that provides a continuous low dose of a steroid for up to 36 months [1.6.2, 1.6.4]. It is indicated for chronic diabetic macular edema in patients who have previously responded well to corticosteroids without a significant rise in eye pressure [1.6.2].

A primary concern with steroid treatments is the potential for side effects like increased intraocular pressure (glaucoma) and cataract formation [1.2.1, 1.4.5].

Comparison of Injection Types


Feature	Anti-VEGF Injections	Corticosteroid Injections/Implants
Primary Mechanism	Blocks VEGF protein to stop leakage and abnormal blood vessel growth [1.2.4].	Reduces inflammation and decreases vascular permeability [1.4.2].
Common Drugs	Avastin, Lucentis, Eylea, Vabysmo [1.2.4].	Triamcinolone, Ozurdex, Iluvien [1.2.1, 1.2.4].
Administration	Frequent injections, typically every 4-12 weeks [1.3.1, 1.5.3].	Single injection or a long-acting implant lasting months to years [1.6.2, 1.6.1].
Key Side Effects	Risks related to injection procedure (e.g., infection, retinal detachment) [1.7.1].	Increased eye pressure (glaucoma), cataract progression [1.2.1, 1.4.2].

The Injection Procedure: What to Expect

The intravitreal injection procedure is performed in an ophthalmologist's office and is relatively quick, often taking less than 30 minutes [1.10.2].

Preparation: The eye is numbed with anesthetic drops or gel to minimize discomfort [1.10.2]. The eye and eyelids are then cleaned with an antiseptic solution like povidone-iodine to prevent infection [1.10.2].
Injection: An eyelid speculum is used to gently hold the eye open [1.10.2]. The medication is then injected through the sclera (the white part of the eye) with a very fine needle [1.2.1, 1.10.2]. Patients may feel slight pressure but typically not pain [1.10.3].
Post-Procedure: After the injection, the eye is cleaned. Common, temporary side effects include seeing floaters (sometimes small air bubbles), a red spot at the injection site, or a gritty sensation [1.11.1, 1.11.2]. These symptoms usually resolve within a day or two [1.11.1].

Conclusion

Intravitreal injections of anti-VEGF medications and corticosteroids are the leading treatments for cystoid macular edema [1.2.1]. By directly targeting the underlying causes of fluid leakage and inflammation in the retina, these therapies can effectively halt disease progression, preserve existing vision, and in many cases, lead to significant visual improvement. The choice between anti-VEGF agents and corticosteroids depends on the specific cause of the CME, the patient's medical history, and a careful evaluation by a retina specialist. Though the thought of an eye injection can be daunting, the procedure is quick, common, and has a high rate of success in managing this sight-threatening condition.

For further reading, the National Eye Institute (NEI) provides comprehensive information on eye conditions and treatments. [1.2.4]

Frequently Asked Questions

The two main types of intravitreal injections for CME are anti-vascular endothelial growth factor (anti-VEGF) drugs and corticosteroids. Both are injected directly into the eye to reduce swelling [1.2.1].

Anti-VEGF medications block the action of a protein called vascular endothelial growth factor (VEGF). This protein promotes abnormal blood vessel growth and leakage, so blocking it helps reduce fluid buildup in the macula [1.2.4].

Corticosteroids are anti-inflammatory drugs. For CME, they can be given as a direct injection (e.g., Triamcinolone) or as a slow-release implant (e.g., Ozurdex, Iluvien) to reduce swelling in the retina over a longer period [1.2.1, 1.2.4].

The procedure is typically not painful. The eye is thoroughly numbed with anesthetic drops or gel before the injection. Patients may feel a brief moment of pressure [1.10.3].

Common, temporary side effects include a gritty feeling, mild discomfort, seeing floaters or small bubbles, and a small red spot on the white of the eye. These usually resolve within a couple of days [1.11.1].

Though rare, more serious risks include eye infection (endophthalmitis), retinal detachment, bleeding in the eye, and increased eye pressure or cataract formation, particularly with steroid use [1.7.1, 1.4.2].

The frequency depends on the medication and the patient's response. Anti-VEGF injections are often given every 4 to 12 weeks, while steroid implants can last from several months to a few years [1.5.3, 1.6.2].