There are 39 million blind people across the world, and a further 246 million suffering from low vision, according to the World Health Organization (WHO). Almost two-thirds are women, the vast majority of them living in low- or middle-income countries.

The WHO says 80 percent of all visual impairment can be prevented or cured with solutions that are relatively easy and low-cost. For example, cataracts, which account for more than half of all cases of blindness, can usually be treated with a 15-minute operation to insert a $2 intraocular lens. But for many blind women, cost is only one of several barriers to diagnosis and treatment.

There is no biological reason for the increased prevalence of vision impairment in women, according to research by the Seva Foundation, a nongovernmental organization that provides eye-care services in over 20 countries. But access to eye healthcare is a major factor.

“In many cultures and regions, within families and the context of communities, blind and vision-impaired women are not considered as important as men to get services,” says Johannes Trimmel, advocacy director of the International Agency for the Prevention of Blindness (IAPB). “It’s a question of financing and cost recovery where investment in families is rather going to men and to the younger generation than to women and the older generation.”

Even where surgery is offered for free, getting to the clinics is often a challenge for many vision-impaired women, as is having the information to know that services are available and that their disability is treatable. The Gender and Blindness Initiative, launched in 1983 by the Canadian Global Health Research Initiative, found that the utilization of eye-care services is strongly associated with the socioeconomic status of women and female literacy – an indicator of educational attainment. Highlighting examples from southern India, the Seva Foundation report Gender and Blindness shows that investment in female education improves all aspects of public health, including eye care, and often without having to add to existing health services.

In low-income settings, blindness or low vision can be a disability with severe consequences. In many parts of the world, people who become blind experience a diminishing quality of life, with the loss of independence, mobility and productivity as well as social status and self-esteem. And their families are likewise negatively affected. According to a Nepali proverb, a blind person is a mouth with no hands – someone who needs so much help in their daily lives that their sighted caregiver loses education and employment opportunities.

Despite the potentially massive economic, psychological and social costs of blindness, all eye-care services are reaching only 10 percent of people who need them, says Suzanne Gilbert, Seva Foundation’s cofounder and senior director of Innovations and Sight.

“If you design programs that are inclusive of women, it’s likely to serve everyone who needs them,” she says. “Figuring out how to reach women requires attention to location, affordability – often meaning it has to be free – and quality of care, not just the outcome but also during the process. Are the patients being rushed? Ignored? Or are they being listened to?”

Compounding the impact of gender prejudice in access to healthcare is age discrimination. Over 80 percent of blind people are aged 50 and above. Vision impairment often appears later in life, and in many contexts is accepted as an inevitable part of aging, even when there are solutions. And that discrimination isn’t just about cultural attitudes and the allocation of health resources, it’s present even in the process of data collection. Organizations tracking women’s health stop when the women reach the end of their fertility: Women over 49 years old are ignored in the Demographic and Health Survey and UNICEF’s Multiple Indicator Cluster Survey.

“Not being counted in statistics and survey means a denial of and exclusion from information, and prevention and support services,” said Justin Derbyshire, CEO of HelpAge International, a network of organizations working with and for older people, in a recent speech to the WHO.

And then there is the fact that, in many countries, funding is often directed toward health issues that are considered more urgent than loss of vision. As far back as the 1980s, the World Bank identified cataract surgery as one of the most cost-effective interventions that can be offered in low- and middle-income countries. But it also notes that these countries face competing health demands like maternal and child care.

With global demographic trends pointing to progressive and rapid population aging, preventable and treatable blindness will only grow as a pressing health and human rights concern. “We have been working on establishing community-based eye care that can reach all who need it,” says Gilbert. “The key factor is not to approach this as a charity, but to provide quality eye-care services for those who are able to pay, and subsidize those who can’t.”

Later this month, IAPB will hold its general assembly, which takes place every four years. Trimmel hopes it will provide an opportunity to address head-on the barriers that women face. “It’s not just the ophthalmologists, it’s not just the service centers, the community health workers, the people working on education or equality generally,” he says. “It needs structures and people to work well together for women to have equal access to eye care.”