In the early 90s, more than one-third of the world’s blind population lived in India, according to most estimates at the time. Of this, 80% were a result of untreated cataract. In other parts of the world, cataracts accounted for only 50% of blindness.

Today, though the statistics have improved, cataracts still affect as many as 74% of Indian adults above age 60. And while the prevalence of cataracts is roughly on par with more developed countries, like the US, on average, Indians develop cataract a whopping 14 years younger than their American counterparts.

“The average age of contracting cataract in the US or Europe is 70 plus. But in India, the condition is growing rampant at age 50,” says Dr. Amar Aggarwal, head of Aggarwal Eye Hospital in Chennai.

With normal vision, light flows through the eye’s lens making it possible for us to perceive clear images. But as we age, the lens, which is composed of protein and water, can become clouded by a cataract, that is, a build-up of protein clusters that prevent light from passing through. The result is clouded, dimmed vision that worsens as proteins continue to cluster irregularly. A cataract can also be caused by a severe blow to the eye, environmental conditions, or genetic birth defects, though these are less common.

Indians appear to be at risk of cataract from a younger age for a variety of reasons. For infants, it is linked to a genetic condition called galactosemia, a deficiency of a critical enzyme needed to breakdown galactose properly, allowing the nutrient to build up in the baby’s eye, among other organs, and damage the lens.

In adults, risk factors are wider ranging. The connection between cataracts and diabetes has been clearly established by numerous studies that have found high blood sugar levels can cause the lens of the eye to swell, which can damage cells and lead to a buildup of protein on the lens. And this could be a reason why Indians are developing cataracts at a younger and younger age than their global peers: Indians are ethnically predisposed to develop diabetes, and the disease is spreading at a fast clip as lives become more sedentary and diets become richer.

Smoking, severe dehydration, and sun exposure over the course of a lifetime can also contribute to cataract, Dr. Aggarwal says.

For a woman, the number times she has given birth may also play a role. A 2002 study linked cataract with giving birth to three or more children, though the study didn’t establish the number of children as a cause, merely as a correlation. In the study, women aged 35 to 45 and mother to three children (the birth rate of the average Indian woman) were twice as likely, regardless of socioeconomic status, to have a cataract than other women their age with fewer children. Any additional births increased their likelihood by roughly 20%.

While a cataract isn’t entirely preventable, there is much people can do to protect their vision. Dr. Aggarwal recommends a diet rich in vegetables — particularly carrot, cucumber and broccoli — which can provide antioxidants that nourish the lens of the eye.

Another important preventative effort is care. Using sunglasses with 100% UV protection combined with getting annual eye exams go a long way to preventing and monitoring eye damage, Dr. Aggarwal says. Exams by an ophthalmologist become particularly important if you start experiencing cataract warning signs — such as fading, dimming, or yellowing of colours, pain or double vision, or poor eyesight at night — since leaving a cataract untreated can allow the lens to harden and burst. In this worst-case scenario, says Dr. Aggarwal, who is also a committee chairman with the Intraocular Implant & Refractive Society of India, an emergency surgery is necessary and it is unlikely full vision will ever be completely restored.

The good news is, cataract can be corrected before this point, and India, over the past 35 years, has been doing a better job of providing treatment. In 1981-82, only half a million cataract surgeries were performed in the country; in 2006, 4.8 million surgeries. This trend is likely to plateau at some point in the near future, though, as forecasts predict India’s cataract burden to grow significantly as the current population ages.

There’s a light at the end of this tunnel-vision, however. Scientists in the US have just successfully tested on dogs a steroid solution that can dissolve cataract and improve vision. While these eye drops are still a long way from being available to humans, it is likely the next generation of elderly Indians will have clearer sight through less invasive procedures and at a fraction of the current cost.