Overview
Definition
A degenerative disease of the macula (the central area of the retina), resulting in a loss of central, high-resolution vision.
Epidemiology
The leading cause of permanent, severe vision loss in developed countries in individuals > 65 years.
Etiology & Risk Factors
- Dry (Atrophic): Accounts for 90%. Accumulation of extracellular debris (drusen) between the retinal pigment epithelium (RPE) and Bruch's membrane.
- Wet (Neovascular): Accounts for 10% but causes 90% of severe vision loss. Abnormal blood vessel growth (choroidal neovascularization) that leaks fluid and blood.
Clinical Symptoms
- Gradual (Dry) or Sudden (Wet) painless loss of CENTRAL vision
- Metamorphopsia: Straight lines appear wavy or distorted (early sign)
- Peripheral vision is SPARED (patients can navigate a room but cannot read or recognize faces)
Clinical Approach
Diagnosis
- Dilated Fundus Exam: Dry AMD shows Drusen (yellow deposits); Wet AMD shows hemorrhages or subretinal fluid
- Amsler Grid: Patient reports wavy or missing lines
- Optical Coherence Tomography (OCT): Highly detailed cross-section of the retina to detect fluid (Wet AMD)
Management
- Dry AMD: Smoking cessation (crucial), AREDS2 vitamin formulation (Antioxidants, Zinc, Lutein) to slow progression
- Wet AMD: Intravitreal Anti-VEGF injections (Bevacizumab, Ranibizumab) to halt and sometimes reverse new blood vessel growth
Complications
- Legal blindness (loss of driving privileges, inability to read)