2 The technology
2.1 Dexamethasone intravitreal implant (Ozurdex, Allergan) incorporates a potent corticosteroid that suppresses inflammation in the eye by inhibiting oedema, fibrin deposition, capillary leakage and phagocytic migration. Corticosteroids inhibit the expression of vascular endothelial growth factor (VEGF), a cytokine that is expressed at increased concentrations in macular oedema and is a potent promoter of vascular permeability. Corticosteroids also prevent the release of prostaglandins, some of which are mediators of cystoid macular oedema.
2.2 Dexamethasone intravitreal implant has a marketing authorisation for the treatment of adult patients with macular oedema following either branch retinal vein occlusion (BRVO) or central retinal vein occlusion (CRVO).
2.3 The most common adverse reactions are increased intraocular pressure and conjunctival haemorrhage. Conjunctival haemorrhage is related to the intravitreous injection procedure rather than the dexamethasone implant. Other common adverse events include ocular hypertension, vitreous detachment, cataract, subcapsular cataract, vitreous haemorrhage, visual disturbance, vitreous opacities, eye pain, photopsia, conjunctival oedema, and conjunctival hyperaemia. For full details of side effects and contraindications, see the summary of product characteristics.
2.4 The cost of a 700-microgram implant and applicator is £870.00 (British National Formulary [BNF] edition 61), excluding VAT. One dexamethasone intravitreal implant is administered usually every 6 months in the affected eye and up to six implants may be given. Costs may vary in different settings because of negotiated procurement discounts.