Cataract surgery is not readily available in many countries, and surgery is needed only if the cataracts are causing problems and generally results in an improved quality of life.About 20 million people worldwide are blind due to cataracts. It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America. Blindness from cataracts occurs in about 10 to 40 per 100,000 children in the developing world, and 1 to 4 per 100,000 children in the developed world. Cataracts become more common with age. In the United States, cataracts occur in 68% of those over the age of 80 years. Additionally they are more common in women, and less common in Hispanic and Black people. Signs and symptoms
Signs and symptoms vary depending on the type of cataract, though considerable overlap occurs. People with nuclear sclerotic or brunescent cataracts often notice a reduction of vision. Nuclear cataracts typically cause greater impairment of distance vision than of near vision. Those with posterior subcapsular cataracts usually complain of glare as their major symptom.The severity of cataract formation, assuming no other eye disease is present, is judged primarily by a visual acuity test. Other symptoms include frequent changes of glasses and colored halos due to hydration of lens.Congenital cataracts can result in amblyopia if not treated in a timely manner. Causes
Age
Age is the most common cause of cataracts. Lens proteins denature and degrade over time, and this process is accelerated by diseases such as diabetes mellitus and hypertension.
Surgery
As of 2015 there is not good evidence comparing surgery to lifestyle change for obesity in children, though there are a number of high quality ongoing studies looking at this issue. Bariatric surgical procedures are increasingly used amongst adolescents with severe adolescent obesity to promote weight loss. Epidemiology
From 1980 to 2013, the prevalence of overweight and obesity in children increased by nearly 50%. Currently 10% of children worldwide are either overweight or obese. In 2014, the World Health Organization established a high-level commission to end childhood obesity.With more than 42 million overweight children around the world, childhood obesity is increasing worldwide. Since 1980, the number of obese children has doubled in all three North American countries, Mexico, the United States, and Canada. Although the rate of childhood obesity in the United States has stopped increasing, the current rate remains high. In 2010, 32.6 percent of 6- to 11-year-olds were overweight, and 18 percent of 6- to 9-year-olds were obese. Canada
The rate of overweight and obesity among Canadian children has increased dramatically in recent years. In boys, the rate increased from 11% in the 1980s to 30% in the 1990s. Brazil
The rate of overweight and obesity in Brazilian children increased from 4% in the 1980s to 14% in the 1990s. In 2007 the prevalence of children overweight and childhood obesity was 11.1% and 2.7% in girls, 8.2% and 1.5% in boys, respectively. United States
The rate of obesity among children and adolescents in the United States has nearly tripled between the early 1980s and 2000.