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Age-related Macular Degeneration (ARMD)

Table of Contents

  • Introduction
  • Aetiology and Risk Factors
  • Classification
  • Clinical Features
  • Differential Diagnosis
  • Investigations
  • Management
  • Complications and Prognosis
  • References
  • Related Notes
  • Test Yourself

Introduction

  • ARMD is a progressive loss of central vision due to drusen formation and retinal pigment epithelium changes.
  • Most common cause of blindness in people over 60 in the UK and Ireland.

Aetiology and Risk Factors

  • No single cause identified; multifactorial with genetic and environmental factors.
  • Risk factors:
  • Age
  • Caucasian ethnicity
  • Family history
  • Smoking
  • Hypertension
  • High-fat diet
  • Aspirin use
  • Sunlight exposure
  • Blue eyes
  • Female gender
  • Previous cataract surgery

Classification

  • Dry (non-exudative) AMD (~90% cases)
  • Characterized by drusen deposits (<63 µm small drusen normal with ageing).
  • Progressive pigmentary changes and geographic atrophy.

  • Slow progression, can lead to advanced AMD with geographic atrophy.

  • Wet (neovascular) AMD

  • Formation of choroidal neovascular membrane driven by VEGF.
  • Acute vision loss and retinal hemorrhage.

AREDS Classification

Type Clinical Features
No AMD Few small drusen (<63µm) or none
Early AMD ≥1 medium drusen (63–124µm) or mild pigment changes
Intermediate AMD ≥1 large drusen (≥125µm) or geographic atrophy not involving fovea
Advanced AMD Geographic atrophy involving fovea or neovascular AMD

Clinical Features

History

  • Progressive central visual loss, difficulty with detail, faces, and contrast.
  • Symptom variation often worse in low light.
  • Acute rapid vision loss indicates wet AMD (ophthalmic emergency).
  • Associated symptoms: visual distortions, central scotomas, metamorphopsia.
  • Assess risk factors: smoking, hypertension, family history, cataract surgery, aspirin use.
  • Impact on activities of daily living, driving status, falls risk.

Examination

  • Visual acuity testing.
  • Amsler grid test: central metamorphopsia.
  • Fundoscopy: drusen, pigment changes, geographic atrophy, subretinal hemorrhage.

Differential Diagnosis

Condition Key Features
Dry AMD Gradual central vision loss, drusen on fundoscopy
Wet AMD Sudden vision loss, retinal hemorrhage
Open-angle glaucoma Peripheral vision loss, optic disc cupping
Cataract Blurred vision, glare, no central scotoma
Diabetic retinopathy Retinal hemorrhages, microaneurysms, history of diabetes
Retinal detachment Flashes, floaters, peripheral vision loss
Central retinal artery occlusion Sudden vision loss, cherry-red macula
Giant cell arteritis Headache, scalp tenderness, jaw claudication

Investigations

  • No reliable blood biomarkers for AMD.
  • Community/non-specialist: Amsler grid for screening.
  • Specialist imaging:
  • Ocular Coherence Tomography (OCT): retinal layer thickness, drusen, neovascular membranes.
  • Fluorescein angiography: detects choroidal neovascularisation.
  • Indocyanine green angiography: for deeper choroidal vessel imaging in hemorrhagic cases.
  • Autofluorescence: assesses geographic atrophy.

Management

  • No cure; focus on preserving vision and quality of life.
  • Lifestyle advice: smoking cessation, cardiovascular risk control, diet, sunlight protection.
  • Dry AMD:
  • Low vision aids.
  • AREDS2 vitamin supplements (vitamins C, E, beta-carotene, zinc, lutein, zeaxanthin).
  • Wet AMD:
  • Intravitreal anti-VEGF injections (Ranibizumab, Bevacizumab, Pegaptanib).
  • Initial monthly injections for 3 months, then individualized dosing.
  • Support:
  • Registration with blind services.
  • Occupational therapy and psychological support.
  • Driving advice based on visual acuity standards.

Complications and Prognosis

  • Injection complications:
  • Chemosis, scleral injection, grittiness.
  • Rare: endophthalmitis (<1%), retinal detachment (<1%), cataract formation (<1%).
  • Disease progression:
  • 1.3%-18% risk of advancing over 5 years depending on stage.
  • 43% risk of advanced disease in fellow eye if one eye affected.
  • Visual loss increases fall/fracture risk.

References

  • Bowling B. Kanski's Clinical Ophthalmology, 8th Ed. 2015.
  • Batterbury M, Murphy C. Ophthalmology, 4th Ed. 2018.
  • Age-Related Eye Disease Study Research Group (AREDS). 1999.
  • Haugsdal J, Sohn E. Age-Related Macular Degeneration Review. 2018.
  • Ghasemi Falavarjani K, Nguyen Q. Adverse Events with Anti-VEGF Injections, 2013.
  • Acute Angle-Closure Glaucoma
  • Amblyopia
  • Anisocoria
  • Anterior Uveitis (Iritis)

Test Yourself

  • [Link to ARMD MCQs and clinical scenarios]

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