Wet Macular Degeneration: Characteristics and Management
Wet macular degeneration is a form of age-related macular degeneration characterized by the development of abnormal blood vessels in the choroid layer underneath the retina, leading to blurred vision and loss of central vision.
Definition and Pathophysiology
Wet age-related macular degeneration (AMD), also known as neovascular AMD, is a progressive deterioration of the retina that involves:
- Development of abnormal blood vessels from the choroidal circulation that penetrate through Bruch's membrane 1
- These new vessels are fragile and can leak fluid or blood into the subretinal space 2
- Results in distortion of vision and rapid loss of central vision compared to the dry form 1, 3
- Represents approximately 10-15% of all AMD cases but accounts for about 90% of severe vision loss due to AMD 4, 5
Epidemiology and Risk Factors
- Prevalence increases significantly with age:
- 2.8% in adults aged 40-59 years
- 13.4% in adults 60 years or older 1
- Overall prevalence of AMD is 6.5% in adults 40 years or older 1
- Leading cause of blindness in adults over 65 years 1, 4
Key risk factors include:
- Advancing age (strongest risk factor) 2
- Smoking (significantly increases risk and progression) 2
- Family history of AMD 1, 2
- Presence of drusen (especially large or soft drusen) 1, 2
- Obesity 2
- Diet low in green leafy vegetables 2
- Elevated cholesterol levels 2
- Cardiovascular disease 2
Clinical Presentation
Patients with wet AMD typically present with:
- Sudden or rapid deterioration of central vision
- Visual distortion (metamorphopsia)
- Central scotoma (blind spot)
- Difficulty recognizing faces
- Problems reading or performing detailed tasks
- Preserved peripheral vision
Diagnosis
Diagnosis of wet AMD involves:
- Comprehensive eye examination with dilated fundus evaluation
- Amsler grid testing to detect metamorphopsia (distortion of straight lines) 2
- Optical Coherence Tomography (OCT) to visualize retinal layers and detect fluid
- Fluorescein Angiography to classify the type of choroidal neovascularization (classic vs. occult) and guide treatment decisions 2
Treatment Options
The mainstay of treatment for wet AMD is:
Anti-VEGF Therapy
- First-line treatment for neovascular AMD 2
- Intravitreal injections of VEGF inhibitors:
- These medications bind and inhibit VEGF, preventing further growth of abnormal blood vessels 7, 6
- Treatment regimens typically require regular injections, often monthly initially 4
Other Treatment Options
- Photodynamic therapy (PDT): Combines verteporfin (a photosensitizing agent) with low-level laser light 1
- Combination therapy: Some studies have explored combining anti-VEGF with PDT 1
- Antioxidant vitamins and minerals: While primarily used for dry AMD, may have some benefit in preventing progression 1
Prognosis and Monitoring
- Early detection and prompt treatment are critical for preserving vision 2
- Anti-VEGF therapy can improve vision in many patients if started early 8
- Regular monitoring is essential as treatment response varies between patients 9
- Up to 25% of patients may not fully respond to anti-VEGF therapy (non-responders) 9
- The contralateral eye in patients with unilateral wet AMD has a high risk of developing the disease and should be monitored closely 2
Prevention Strategies
- Smoking cessation 2
- Maintaining a healthy body mass index 2
- Diet rich in green leafy vegetables and omega-3 fatty acids
- Regular eye examinations, especially for those with risk factors
- Use of AREDS2 formula supplements in appropriate patients (vitamins C, E, zinc, copper, lutein, and zeaxanthin) 2
- Protection from excessive sunlight exposure 2
Wet AMD represents a serious threat to vision, but with early detection and modern treatments, visual outcomes have significantly improved compared to previous decades.