How should I treat cystoid macular edema?

Treatment of Cystoid Macular Edema

Intravitreal anti-VEGF agents should be the first-line treatment for cystoid macular edema due to their favorable risk-to-benefit profile and demonstrated efficacy in reducing macular thickness and improving visual acuity. 1

First-Line Treatment: Anti-VEGF Therapy

Anti-VEGF Agent Selection

• Ranibizumab (0.5 mg) - FDA-approved for macular edema following retinal vein occlusion 2
• Aflibercept (2 mg) - FDA-approved for macular edema following central and branch retinal vein occlusion 3
• Bevacizumab (1.25 mg) - Off-label but effective and more cost-effective option 1

Treatment Protocol

1. Initial treatment: Monthly intravitreal injections for 3-6 months
2. Evaluation: Assess response after each injection with OCT imaging and visual acuity testing
3. Maintenance: After initial response, consider:
   • Monthly continued injections if persistent edema
   • Treat-and-extend protocol (gradually increasing intervals between injections)

Expected Outcomes

• Reduction in central retinal thickness measurable as early as 2 weeks after injection 4
• Visual acuity improvement in most patients (typically 2+ lines on Snellen chart) 4, 5
• Complete resolution of subretinal fluid in 50-100% of patients depending on etiology 1

Second-Line Treatment: Intravitreal Corticosteroids

If inadequate response to anti-VEGF therapy (defined as persistent edema after 3-6 monthly injections):

Options:

• Triamcinolone acetonide (1-4 mg) 1
• Dexamethasone implant (Ozurdex) - Particularly effective for persistent edema 1

Considerations:

• Higher risk of side effects including cataract formation and elevated intraocular pressure
• Particularly effective in cases with diffuse leakage from the choroid or extensive leakage from the optic disc 5
• May require IOP monitoring every 4-6 weeks after injection

Third-Line Treatment: Laser Photocoagulation

For specific etiologies (particularly diabetic macular edema or branch retinal vein occlusion):

• Grid laser photocoagulation can be considered if anti-VEGF and corticosteroid treatments fail 1
• Apply to areas of retinal thickening between 500-3000μm from the center of the macula 1
• Spot size: 50-60μm, duration: 0.05-0.1 seconds 1

Treatment Algorithm Based on Etiology

For CME due to Retinal Vein Occlusion:

1. Begin with anti-VEGF (ranibizumab or aflibercept) monthly for 3-6 months
2. If inadequate response, switch to intravitreal corticosteroids
3. Consider grid laser for persistent BRVO-associated edema

For CME due to Uveitis:

1. Begin with anti-VEGF therapy (bevacizumab or ranibizumab)
2. If inadequate response or diffuse choroidal leakage on fluorescein angiography, switch to intravitreal triamcinolone 5
3. Consider systemic immunosuppression for bilateral or recurrent disease

Injection Technique

• Pre-injection topical anesthesia
• Apply povidone-iodine directly over injection site
• Use sterile 30-gauge needle
• Inject 3.0-4.0mm posterior to limbus
• Confirm central artery perfusion after injection 1

Monitoring and Follow-up

• OCT imaging to assess central retinal thickness
• Visual acuity testing
• Monitor for complications:
  • Endophthalmitis (rare)
  • Elevated intraocular pressure (particularly with corticosteroids)
  • Cataract progression (with corticosteroids)

Special Considerations

• For refractory cases that fail to respond to a specific anti-VEGF agent, switching to another anti-VEGF agent (particularly aflibercept) may be effective 6
• Patients with extensive foveal RPE atrophy should be counseled regarding risk of further vision loss following photodynamic therapy 1
• The use of anti-VEGF injections for treating certain conditions may be off-label, requiring informed consent 1

Remember that early treatment of cystoid macular edema is essential to prevent permanent vision loss due to chronic structural changes in the macula.