By Dr Ananya Mandal, MD
Cataracts are the most common worldwide cause of impaired vision and are a particular problem in developing countries, where they commonly lead to blindness.
As a common illness in older individuals, the fact that people are living longer every decade means the prevalence of cataracts is on the rise and cataracts are more common today than ever before.
Estimates predict that currently cataracts affect around 22 million adults aged 40 or older and that by the year 2020, this number will have approximately doubled.
In the UK alone, age-related cataracts are thought to affect more than half of those aged over 65 years to some degree. In the United States, changes in the health of the eye lens due to aging have been reported by 42% of those aged 52 to 64 years, 60% of those aged 65 to 74 years, and by 91% of those aged 75 to 85 years.
Australian studies have shown that the prevalence of cataract doubles with each decade of age after 40 years and that nearly everyone aged 90 years or older is affected by cataracts. Other developed countries show similar incidence and prevalence of cataract.
Cataracts are a particular problem in developing nations. For example, one study showed that in India, the prevalence of cataracts is three times greater than in the United States, with 82% of Indians aged 75 to 83 years affected by cataracts, compared with only 46% of US individuals form the same age group.
It has been estimated that cases of cataracts will continue to rise predominantly in developing countries where population increases will be the greatest. As the number of individuals aged over 65 years continues to increase, so will the incidence of cataract and the need for cataract surgery.
Reviewed by Sally Robertson, BSc