Ocular prostheses are made for a social programme benefiting those unable to afford one, in Cancun March 6, 2015. Specialist Doctors for Maxillofacial Prosthetics at the National Autonomous University of Mexico (UNAM) and the Autonomous University of Campeche in conjunction with the System for Integral Family Development Cancun, as part of the programme, treated more than 100 people with various visual impairments. REUTERS/Victor Ruiz Garcia (MEXICO - Tags: SOCIETY POVERTY) 

A girl receives an ocular prosthesis during a social programme benefiting those unable to afford one, in Cancun March 6, 2015. Specialist Doctors for Maxillofacial Prosthetics at the National Autonomous University of Mexico (UNAM) and the Autonomous University of Campeche in conjunction with the System for Integral Family Development Cancun, as part of the programme, treated more than 100 people with various visual impairments. REUTERS/Victor Ruiz Garcia (MEXICO - Tags: SOCIETY POVERTY) 

A doctor plants eyelashes on an ocular prosthesis for a social programme benefiting those unable to afford one, in Cancun March 6, 2015. Specialist Doctors for Maxillofacial Prosthetics at the National Autonomous University of Mexico (UNAM) and the Autonomous University of Campeche in conjunction with the System for Integral Family Development Cancun, as part of the programme, treated more than 100 people with various visual impairments. REUTERS/Victor Ruiz Garcia (MEXICO - Tags: SOCIETY POVERTY TPX IMAGES OF THE DAY) 

People sit on beds while waiting for treatment at a hospital after undergoing cataract removals from a free eye surgery camp, in the northern Indian city of Amritsar December 5, 2014. Fifteen Indians lost their sight after a doctor used suspected infected equipment to remove cataracts at the free eye surgery camp, the latest incident to highlight the dangers of shoddy medical treatment in the country. A criminal investigation has been launched against the non-governmental organization and the doctors who carried out the operations, mainly on elderly women, without consulting health authorities. REUTERS/Munish Sharma (INDIA - Tags: CRIME LAW HEALTH SOCIETY) 

A man sits on a bed after going through free eye surgery at the Phyo charity clinic in Yangon September 4, 2014. Free eye surgeries at the clinic are provided to people such as the elderly and is part of a special initiative organized by the China Foundation for Peace and Development (CFPD) and Myanmar's Alinyaung (Brightness) Foundation (MAF). About 200 free eye surgeries will take place over a span of four days. REUTERS/Soe Zeya Tun (MYANMAR - Tags: HEALTH) 

A patient goes through free eye surgery at the Phyo charity clinic in Yangon September 4, 2014. Free eye surgeries at the clinic are provided to people such as the elderly and is part of a special initiative organized by the China Foundation for Peace and Development (CFPD) and Myanmar's Alinyaung (Brightness) Foundation (MAF). About 200 free eye surgeries will take place over a span of four days. REUTERS/Soe Zeya Tun (MYANMAR - Tags: HEALTH) 

A patient goes through free eye surgery at the Phyo charity clinic in Yangon September 4, 2014. Free eye surgeries at the clinic are provided to people such as the elderly and is part of a special initiative organized by the China Foundation for Peace and Development (CFPD) and Myanmar's Alinyaung (Brightness) Foundation (MAF). About 200 free eye surgeries will take place over a span of four days. REUTERS/Soe Zeya Tun (MYANMAR - Tags: HEALTH) 

An ophthalmologist conducts free cataract surgery on a patient in Manila January 16, 2011. In celebration of the 400th anniversary of the University of Santo Tomas, the Tzu Chi Foundation, a Buddhist charitable organization, has collaborated with doctors from the university's ophthalmology department to provide free cataract removal operations for 400 patients from needy families. REUTERS/Cheryl Ravelo (PHILIPPINES - Tags: HEALTH SOCIETY EDUCATION) 

An ophthalmologist prepares to conduct cataract surgery on a patient at a clinic in Manila January 16, 2011. In celebration of the 400th anniversary of the University of Santo Tomas, the Tzu Chi Foundation, a Buddhist charitable organization, has collaborated with doctors from the university's ophthalmology department to provide free cataract removal operations for 400 patients from needy families. REUTERS/Cheryl Ravelo (PHILIPPINES - Tags: HEALTH SOCIETY EDUCATION) 

Indigenous people sit after undergoing eye surgery in the Cartucho community during the last day of the "Expedicionarios da Saude" (Brazilian Health Expeditions) medical expedition to the area in Santa Isabel do Rio Negro, in Amazonas state, northern Brazil November 11, 2010. The "Expedicionarios da Saude" arrange two annual expeditions of volunteer doctors to set up a mobile hospital in the Amazon rainforest to give clinical and surgical attention to indigenous and local people. In the six days, the expedition assisted about 815 people and made around 160 surgeries, mainly cataracts and hernias, the most common diseases found within the local population. REUTERS/Ricardo Moraes (BRAZIL - Tags: SOCIETY HEALTH) 

A woman from the Bare tribe rests on her hammock after her eye surgery by doctors from a "Expedicionarios da Saude" (Brazilian Health Expeditions) medical expedition to the Cartucho community in Santa Isabel do Rio Negro, in Amazonas state, northern Brazil, November, 7, 2010. The organization carries out two annual expeditions to the Amazon Rainforest with voluntary doctors to provide clinical and surgical treatment for members of indigenous tribes and residents. REUTERS/Ricardo Moraes (BRAZIL - Tags: HEALTH SOCIETY) 

A resident goes through eye surgery conducted by U.S. doctors of Madigan Army Medical Center at the Armed Forces Central Hospital in Santo Domingo October 11, 2010. U.S. military medical specialists from the Madigan Army Medical Center of Ft. Lewis, WA. and Doctors of Armed Forces of the Dominican Republic conducted surgeries without any charge on more than 400 poor patients with cataract problems, glaucoma and retinopathies, from all over the country, according to local media. REUTERS/Eduardo Munoz (DOMINICAN REPUBLIC - Tags: HEALTH SOCIETY MILITARY) 

A woman touches her eye after undergoing cataract surgery at Sardjito hospital in Yogyakarta May 20, 2010. A total of 30 villagers received new lenses for their eyes as part of an initiative by Gajah Mada University offering free cataract surgery for the poor. Indonesia has the highest record of blindness in Asia, with around 4 million visually-impaired people, according to an Indonesian Eye Specialists Association official. REUTERS/Dwi Oblo (INDONESIA - Tags: SOCIETY HEALTH) 

A doctor carries out a cataract operation at Sardjito hospital in Yogyakarta May 20, 2010. A total of 30 villagers received new lenses for their eyes as part of an initiative by Gajah Mada University offering free cataract surgery for the poor. Indonesia has the highest record of blindness in Asia, with around 4 million visually-impaired people, according to an Indonesian Eye Specialists Association official. REUTERS/Dwi Oblo (INDONESIA - Tags: HEALTH SOCIETY IMAGES OF THE DAY) 

A doctor conducts cataract surgery at Qadr hospital's operation room in Tangerang, Indonesia's Banten province, October 17, 2009. A total of 67 villagers received new lenses for their eyes as part of a joint initiative by the Indonesian Lions Club Foundation and the Indonesian Eye Specialists Association (perdami) offering free cataract surgery for the poor. Indonesia has the highest record of blindness in Asia, with around four million visually-impaired people, according to a Perdami official. A cataract operation costs between 5 million to 10 million Indonesian rupiah ($500 to $1000) and the initiative helps conduct cataract surgery for those who are not able to afford medical treatment. REUTERS/Beawiharta (INDONESIA SOCIETY HEALTH IMAGES OF THE DAY) 

A cataract patient undergoes free surgery at Cipto Mangunkusumo hospital in Jakarta October 18, 2008. About 100 cataract patients received free surgery during World Sight Day at the hospital on Saturday. REUTERS/Dadang Tri (INDONESIA) 

A cataract patient waits for treatment after surgery as others wait their turn at Cipto Mangunkusumo hospital in Jakarta October 18, 2008. About 100 cataract patients received free surgery during World Sight Day at the hospital on Saturday. REUTERS/Dadang Tri (INDONESIA) 

Johana Davila is under an eye surgery in Puerto Ayacucho in the southern Amazonas state, 831 km (520 miles) from Caracas, April 4, 2008. One of President Hugo Chavez's health initiatives called Mission Miracle or 'Mision Milagro', is now in its fourth year providing free eye surgery to Latin America's poor. The project has helped more than 400,000 people recover from blindness or improve their vision, according to Venezuelan officials. REUTERS/Edwin Montilva (VENEZUELA) 

Johana Davila is under an eye surgery in Puerto Ayacucho in the southern Amazonas state, 831 km (520 miles) from Caracas, April 4, 2008. One of President Hugo Chavez's health initiatives called Mission Miracle or 'Mision Milagro', is now in its fourth year providing free eye surgery to Latin America's poor. The project has helped more than 400,000 people recover from blindness or improve their vision, according to Venezuelan officials. REUTERS/Edwin Montilva (VENEZUELA) 

Johana Davila is under an eye surgery in Puerto Ayacucho in the southern Amazonas state, 831 km (520 miles) from Caracas, April 4, 2008. One of President Hugo Chavez's health initiatives called Mission Miracle or 'Mision Milagro', is now in its fourth year providing free eye surgery to Latin America's poor. The project has helped more than 400,000 people recover from blindness or improve their vision, according to Venezuelan officials. REUTERS/Edwin Montilva (VENEZUELA) 

A French eye surgeon uses a microscope as he performs an operation on a patient with a detached retina (retinal detachment surgery) in an operating room at the Ambroise Pare hospital in Marseille, on April 3, 2008. REUTERS/Jean-Paul Pelissier (FRANCE) 

A French eye surgeon performs an operation on a patient with a detached retina (retinal detachment surgery) in an operating room at the Ambroise Pare hospital in Marseille, on April 3, 2008. REUTERS/Jean-Paul Pelissier (FRANCE) 

French eye surgeons perform an operation on a patient with a detached retina (retinal detachment surgery) in an operating room at the Ambroise Pare hospital in Marseille, on April 3, 2008. REUTERS/Jean-Paul Pelissier (FRANCE) 

French eye surgeons perform an operation on a patient with a detached retina (retinal detachment surgery) in an operating room at the Ambroise Pare hospital in Marseille, on April 3, 2008. REUTERS/Jean-Paul Pelissier (FRANCE) 

Recovered cataract patients wait to be examined after undergoing operations inside a hospital in Xilinhot in Inner Mongolia, China September 21, 2007. Cataract is a major cause of blindness around the world. There are at least 1 million new cataract cases each year in China. The total number of cases could balloon to 167 million by 2020 because of an ageing population, according to ORBIS, a group that aims to treat and prevent blindness in developing countries. Picture taken September 21, 2007. To match feature HEALTH CHINA/CATARACTS REUTERS/Bobby Yip (CHINA) 

A cataract patient is examined inside a hospital in Xilinhot in Inner Mongolia, China September 21, 2007. Cataract is a major cause of blindness around the world. There are at least 1 million new cataract cases each year in China. The total number of cases could balloon to 167 million by 2020 because of an ageing population, according to ORBIS, a group that aims to treat and prevent blindness in developing countries. Picture taken September 21, 2007. To match feature HEALTH CHINA/CATARACTS REUTERS/Bobby Yip (CHINA) 

Patients recovering from cataract operations are seen dressed in traditional Mongolian costumes before attending a ceremony marking the inauguration of Project Vision, a Hong Kong charity, at a hospital in Xilinhot, Inner Mongolia September 22, 2007. Cataracts are a major cause of blindness around the world. In China, nine million people are blind, half of them due to cataracts. Project Vision aims to create 100 centres around the country to perform cataract operations in places that need them most. REUTERS/Bobby Yip (CHINA) 

A nurse cleans the eye of a cataract patient at a hospital in Xilinhot, Inner Mongolia September 21, 2007. Cataracts are a major cause of blindness around the world. In China, nine million people are blind, half of them due to cataracts. REUTERS/Bobby Yip (CHINA) 

A cataract patient waits to be examined inside a hospital in Xilinhot, Inner Mongolia September 21, 2007. Cataracts are a major cause of blindness around the world. In China, nine million people are blind, half of them due to cataracts. REUTERS/Bobby Yip (CHINA)