The aim of this thesis was to investigate the prevalence and impact of age-related macular degeneration (AMD) causing visual impairment in people aged 75 years and above in the UK. A secondary objective was to investigate a small number of potential risk factors for AMD. This was an add-on study to the MRC Trial of the Assessment and Management of Older People in the Community. The prevalence of AMD causing visual impairment was estimated at 3.7% (95% confidence interval 3.2% to 4.2%) in people aged 75 years and above. This prevalence increased sharply with age. There was a higher risk of AMD causing visual impairment in women. There were estimated to be approximately 192,000 people aged 75 years and above in the UK living in the community with visual impairment due to AMD (95% confidence interval 144,000 to 239,000) of whom 60,000 are aged 90 years or above. The prevalence of AMD causing visual impairment did not vary by socio-economic group or region. After controlling for appropriate confounding factors, compared to people not visually impaired, people visually impaired due to AMD were more likely to have functional difficulties, report poor health and be depressed. They were more likely to be in the worst quintile for the home management and mobility dimensions of the Sickness Impact Profile (SIP). After controlling for appropriate confounding factors including binocular acuity score, compared to people visually impaired due to other causes, people visually impaired due to AMD were more likely to have functional difficulties and report poor health and less likely to be in the worst quintile for SIP body care and movement dimension or die. There was an association between smoking status and risk of being visually impaired due to AMD. This effect was particularly strong in people aged 75-79 years of age. In these people there was a dose-response relationship between pack years of smoking and risk of AMD causing visual impairment. There were no statistically significant associations between alcohol consumption, cardiovascular disease and reproductive factors (in women) and AMD causing visual impairment.