The Ozurdex implant manages chronic retinal inflammation and swelling by delivering medication directly inside the eye. This treatment involves injecting a tiny, rod-shaped implant into the vitreous, the gel-like substance filling the eye’s center. This localized method provides sustained release of a high concentration of medication directly to the retina and macula. This maximizes the anti-inflammatory effect, providing a therapeutic benefit that lasts for several months.
Composition and Mechanism of Action
The active ingredient in the implant is dexamethasone, a highly potent corticosteroid medication. Dexamethasone functions by suppressing the inflammatory response, which is the underlying cause of retinal swelling in many eye diseases. It achieves this by inhibiting the activity of various inflammatory cytokines and chemical mediators within the eye.
The medication is embedded within a matrix made of a biodegradable polymer called poly(D,L-lactide-co-glycolide), or PLGA. This polymer matrix slowly dissolves over time through hydrolysis, continuously releasing dexamethasone into the vitreous cavity for up to six months. The sustained-release design allows a steady therapeutic dose to be maintained over an extended period. This method minimizes the risk of systemic side effects that can occur when corticosteroids are taken orally. The United States Food and Drug Administration (FDA) has approved this implant for specific chronic retinal conditions.
Primary Conditions Treated
The primary indications for the implant are conditions characterized by persistent inflammation and fluid accumulation, known as macular edema. One major use is for non-infectious uveitis affecting the posterior segment of the eye, where inflammation originates from an autoimmune response. Delivering the corticosteroid directly to the inflamed tissues effectively reduces swelling.
The implant also treats macular edema that develops following a Retinal Vein Occlusion (RVO), which can be either a Branch RVO or a Central RVO. A third major indication is Diabetic Macular Edema (DME), particularly in patients with an artificial lens implant or those who have responded poorly to other therapies. In all these cases, the goal is to suppress the inflammatory cascade that drives the damaging retinal swelling.
The Implantation Procedure
The implantation is a brief, in-office procedure performed under sterile conditions while the patient remains awake. Preparation involves applying topical anesthetic drops and often an additional injection of a numbing agent beneath the conjunctiva for comfort. The eye is then disinfected with an antiseptic solution to minimize infection risk.
A specialized, single-use applicator containing the rod-shaped implant is used for the injection. The physician inserts the fine needle through the sclera into the vitreous cavity at the pars plana. This site is chosen because it is free of blood vessels and nerves. During injection, the patient typically feels only pressure and may hear a faint clicking sound as the implant is released.
The applicator is then withdrawn. Immediate post-procedure care includes applying antibiotic drops or ointment. The patient is monitored briefly before being discharged with follow-up instructions.
Potential Side Effects and Monitoring
Treatment with this corticosteroid implant carries two primary side effects requiring careful management. The most common is an increase in Intraocular Pressure (IOP), often peaking around eight weeks after injection. This elevated pressure can sometimes lead to glaucoma and may require treatment with pressure-lowering eye drops.
The second major risk is the formation or progression of a cataract. This risk is pronounced with repeated treatments in patients who still have their natural lens (phakic eyes). Patients who have previously undergone cataract surgery are not at risk. Regular ophthalmological monitoring, including routine IOP checks and lens examinations, is mandatory. Less common but serious risks are associated with the intravitreal injection itself.
Rare Complications
- Severe eye infection (endophthalmitis).
- Retinal detachment.
- Vitreous hemorrhage.
- Migration of the implant into the front of the eye.
Patients must contact their physician immediately if they experience new or worsening eye pain, redness, or a sudden decrease in vision following the procedure.
Treatment Duration and Re-treatment
The therapeutic effect of a single implant injection typically lasts between three and six months. This duration is determined by the slow dissolution rate of the PLGA polymer matrix, which ensures a sustained level of dexamethasone is maintained. As the polymer degrades, it is naturally absorbed by the eye, leaving no residue behind.
The decision to re-treat is based on a clinical assessment of the recurrence of the underlying condition, not a fixed schedule. Physicians look for signs that the macular edema or inflammation has returned, often confirmed using Optical Coherence Tomography (OCT) to measure retinal thickness. Re-injection criteria include a measurable increase in central retinal thickness (e.g., over 50 to 100 micrometers from the lowest recorded level). Re-treatment is also considered if the patient experiences a decline in visual acuity, such as a loss of five or more letters on an eye chart.