Macular edema is a common, sometimes temporary, cause of reduced central vision. It may show: (1) A diffuse pattern of macular thickening and fluid accumulation, with or without associated hemorrhages and exudates (see also Diabetes – macular edema);
(2) A cystic accumulation of fluid within the retina, centred around the macula, known as cystoid macular edema (CME). CME occurs in a variety of ocular conditions that increase vascular permeability, thought to arise in some cases due to prostaglandin-mediated inflammation. CME is more common after surgical complications, for example, posterior capsule rupture with damage to the vitreous.
(3) Retinal traction in the macular area (see also Vitreomacular traction syndrome).
- Vascular disease – Diabetic retinopathy, Retinal vein occlusions, Hypertensive retinopathy, Radiation retinopathy, Choroidal neo-vascularisation
- Ocular inflammatory disease – Uveitis, retinal vasculitis,
- Post-operative – Aphakic/pseudophakic CME, laser treatment
- Retinal degenerations and Inherited dystrophies – Age-related macular degeneration, Retinitis pigmentosa
- Drug-induced – prostaglandin analogues, dipivefrin and adrenaline
- Vitreous traction – Epiretinal membrane, Vitreomacular traction syndrome
- Intraocular tumours
Decreased central vision; May be a history of recent ocular surgery
Visual acuity is usually reduced and the foveal light reflex often appears irregular. Slit lamp biomicroscopy reveals loss of the foveal depression, retinal thickening, and there may be multiple small cysts in the foveal region. Optic nerve head swelling or intra-retinal haemorrhage may be present. In severe, chronic cases of CME, cysts occasionally coalesce, resulting in the formation of a lamellar macular hole and permanent damage to central vision. The examination should also include a search for evidence of associated conditions, e.g. uveitis, choroidal melanoma or surgical complications.
Prolonged edema increases the risk of permanent retinal damage and visual loss.
Macular Hole, Central Serous Chorioretinopathy, Choroidal Neovascularization.
Conditions listed under classification, above.
Fluorescein angiography of CME characteristically shows dye leakage around the fovea, in a petaloid (flower petal) configuration due to the radial arrangement of nerve fibres around the fovea. Other pathological changes such as choroidal neovascularization (CNV) may be evident. Optical coherence tomography (OCT) enables non-invasive confirmation of macular edema and may show vitreous traction or CNV.
The underlying cause, if present, is treated appropriately. For example, medications such as topical prostaglandin analogues may require cessation. In many cases (e.g., pseudophakic CME), a high rate of recovery is expected, and no specific treatment is required. The incidence of symptomatic CME after cataract surgery has fallen since the introduction of phacoemulsification and extracapsular procedures.
In general, therapeutic intervention in post-operative CME is appropriate in prolonged disease (over 6 months), and in high-risk patients with pre-existing inflammatory eye disease or prior history. Topical non-steroidal anti-inflammatory agents (NSAIDs) – e.g., diclofenac 0.1%, or ketorolac 0.5% q.i.d. or corticosteroids e.g., prednisolone 1% q.i.d. are common first-line agents. Their effect may be attributable to blockade of prostaglandin synthesis.
Laser treatment, Incisional surgery
Depending on the cause, duration and severity of macular edema, indicated treatments may include oral medications (NSAIDs, corticosteroids or acetazolamide), intravitreal steroids (e.g., triamcinolone), laser treatment and vitrectomy. See the Management sections in the respective conditions.
Macular edema associated with age-related macular degeneration and choroidal neovascularization. Hemorrhages and lipid exudates are evident.
Ocular coherence tomography (OCT) image showing cystic macular edema (open spaces within the retina) secondary to choroidal neovascularization (red colored section, pushing up under the largest cyst). For comparison, a normal OCT image is also shown (inset).