What are the differences between wet macular degeneration and dry macular degeneration?

Differences Between Wet and Dry Macular Degeneration

Wet macular degeneration is characterized by abnormal blood vessel growth under the retina, while dry macular degeneration involves atrophy of retinal layers and accumulation of waste materials, with distinct treatment approaches for each type. 1, 2

Key Differences

Pathophysiology

• Dry AMD:

  • Most common form (85-90% of cases)
  • Progressive deterioration of the retina
  • Atrophy of retinal layers and retinal pigmented epithelial cells
  • Accumulation of waste materials (drusen) under the retina as old cells die 1, 2

• Wet AMD:

  • Less common form (10-15% of cases)
  • Development of abnormal blood vessels in the choroid layer underneath the retina
  • Often develops in patients who already have dry AMD
  • Can lead to vision loss much more rapidly than dry AMD 1, 2

Disease Progression

• Dry AMD: Generally progresses slowly over years
• Wet AMD: Can cause rapid vision deterioration over weeks to months 2

Treatment Options

Dry AMD

• Currently no FDA-approved treatments to reverse damage
• Management focuses on:
  • AREDS2 formulation containing antioxidant vitamins (vitamin C, vitamin E), zinc, copper, lutein, and zeaxanthin to reduce risk of progression in high-risk patients
  • Avoid beta carotene formulations, especially in current or former smokers (increased lung cancer risk)
  • Lifestyle modifications including smoking cessation
  • Regular monitoring for conversion to wet AMD 3, 2

Wet AMD

• Primary treatment: Anti-VEGF (vascular endothelial growth factor) inhibitors
  • Administered through intravitreal injections
  • Examples include ranibizumab (Lucentis), aflibercept, bevacizumab (Avastin)
  • These medications stop the growth of abnormal blood vessels
  • Can improve vision if diagnosed early, but cannot repair existing damage
  • Requires regular ongoing injections 1, 2, 4

Visual Outcomes

• Dry AMD: Typically causes gradual central vision loss
• Wet AMD: Can cause more severe and rapid vision loss if left untreated, but has potential for vision improvement with prompt anti-VEGF therapy 5

Clinical Monitoring Considerations

Monitoring

• Both forms require regular ophthalmologic examinations
• Dry AMD patients should be taught to self-monitor for sudden vision changes that might indicate conversion to wet AMD
• Patients with wet AMD require more frequent monitoring due to risk of disease activity recurrence 3

Patient Perception

• Patients with bilateral wet AMD tend to have poorer self-assessment of visual acuity and quality of life compared to those with unilateral involvement 5

Emerging Research

• Research continues for both forms, with greater focus on finding effective treatments for dry AMD
• Experimental treatments for dry AMD include microcurrent stimulation, though evidence is limited 6
• For wet AMD, research focuses on longer-acting anti-VEGF agents and combination therapies 4, 7

Clinical Pitfalls to Avoid

• Don't confuse dry AMD with dry eye syndrome, which has completely different treatment approaches 3
• Don't delay referral to ophthalmology for patients with sudden vision changes, as prompt treatment of wet AMD is critical for preserving vision
• Don't recommend beta carotene-containing supplements to current or former smokers due to increased lung cancer risk 3