Ozurdex

Ozurdex (Dexamethasone Intravitreal Implant): Use, Benefits, and Indications

Ozurdex is a biodegradable intravitreal implant that releases dexamethasone (0.7 mg), a high-potency corticosteroid, directly into the vitreous humor. Its design allows for sustained drug release for up to 6 months, reducing the need for frequent injections. Its uses, benefits, and indications, supported by clinical evidence, are detailed below.

1. Mechanism of Action and Pharmacology

Anti-inflammatory and antiangiogenic: Dexamethasone inhibits multiple inflammatory cytokines (VEGF, prostaglandins, interleukins). This reduces vascular permeability, retinal edema, and inflammatory cell migration.

Sustained release: The biodegradable polymer (PLGA) degrades into water and CO₂, gradually releasing dexamethasone. Systemic exposure is minimal (<2% vs. oral doses).

Administration: Single intravitreal injection by an ophthalmologist, under aseptic conditions. Requires pre/post-injection antibiotic prophylaxis.

2. Approved Indications

Ozurdex is indicated for adults in:

Diabetic Macular Edema (DME):

Pseudophakic patients (without a natural lens).

Cases refractory to anti-VEGF or where these are unsuitable.

Post-Retinal Vein Occlusion Macular Edema:

Branch Vein Occlusion (BRVO) or Central Occlusion (CRVO).

Non-Infectious Posterior Uveitis:

Inflammation of the posterior segment with symptoms such as floaters or visual loss.

⚠️ Key Contraindications:

Active ocular infections (herpes, fungal), uncontrolled glaucoma (cup-to-disc ratio >0.8), posterior lens capsule rupture, or anterior chamber intraocular lenses.

3. Clinical Benefits

Rapid Visual Improvement: In DME and BRVO/CRVO, peak efficacy is reached at 60 days:

+10 letters in visual acuity (vs. +3 with placebo).

Reduction in central macular thickness of up to 59%.

Extended Duration: Sustained effect for 4-6 months, allowing extended intervals between treatments.

Advantages vs. Other Therapies

In pseudophakic or vitrectomized patients: Greater drug retention vs. anti-VEGF agents.

First-line in specific cases:

Patients with recent thromboembolic events (low risk vs. anti-VEGF agents).

Imminent cataract surgery (avoids interference).

Cost-effectiveness: Fewer annual injections vs. anti-VEGF.

4. Limitations and Risks

Common Adverse Effects

Cataracts: Incidence of 68% in phakic patients; surgery is required in 61% of cases.

Elevated IOP:

Occurs in 25-28% of patients (vs. 4% with placebo).

Controllable with topical medication in 42% of cases; surgery in 1-5%.

Conjunctival hemorrhage

(23%) and ocular pain (7%).

Restrictions on Use

Do not apply to both eyes simultaneously (lack of data).

Mandatory monitoring: Intraocular pressure (IOP) at 72 hours and monthly; cataract evaluation every 6 months.

5. Clinical Protocol and Practical Considerations

Retreatment:

Considered if: Visual acuity <84 letters or macular thickness >250 μm.

Minimum interval: 6 months.

Alternatives when contraindicated:

Anti-VEGF (ranibizumab, aflibercept) for DME/BRVO.

Fluocinolone implant (Iluvien®) for chronic DME