Macular Degeneration
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Macular degeneration is a progressive disease affecting the macula, leading to central vision loss. It is the most common cause of blindness in older adults.
Aetiology
- Age related macular degeneration (AMD): classified into dry (atrophic) and wet (neovascular) forms.
- Genetic factors: variants in the complement factor H gene increase risk.
- Environmental factors: smoking, UV exposure, and poor diet contribute to pathogenesis.
Pathophysiology
- Dry AMD involves gradual accumulation of drusen and retinal pigment epithelium atrophy.
- Wet AMD is characterised by choroidal neovascularisation, leading to exudation, haemorrhage, and fibrosis.
- Progressive central vision loss occurs due to macular dysfunction.
Risk Factors
- Advanced age.
- Family history of macular degeneration.
- Smoking.
- Obesity and cardiovascular disease.
- Prolonged UV light exposure.
- Low dietary intake of antioxidants.
Signs and Symptoms
- Central vision loss: gradual in dry AMD, sudden in wet AMD.
- Distorted vision (metamorphopsia): straight lines appear wavy.
- Scotomas: central blind spots.
- Difficulty reading or recognising faces: due to macular involvement.
Investigations
- Fundoscopy: detects drusen deposits and retinal changes.
- Optical coherence tomography (OCT): assesses macular thickness and fluid accumulation.
- Amsler grid test: used for self-monitoring of central vision changes.
Management
1. Dry AMD:
- Lifestyle modifications: smoking cessation, UV protection, and healthy diet rich in antioxidants.
- AREDS2 supplements: lutein, zeaxanthin, vitamin C, vitamin E, and zinc slow progression.
- Low vision aids: magnifiers and adaptive lighting.
2. Wet AMD:
- Anti-VEGF therapy: intravitreal injections of ranibizumab, aflibercept, or bevacizumab.
- Photodynamic therapy: used in some cases to reduce neovascularisation.
- Laser photocoagulation: occasionally used for extrafoveal lesions.
3. Referral:
- Ophthalmology: urgent referral for wet AMD, routine referral for dry AMD.
- Low vision services: for visual rehabilitation.