GiveWell carries out research into charities it considers promising on an ongoing basis and chooses a handful of organisations every year to which it urges people to donate, claiming them to be the most effective in the world.
Sightsavers was selected by GiveWell because of its work on treating children for parasitic infections, also called deworming, which the evaluator said had a "strong track record and excellent cost-effectiveness".
GiveWell also praised Sightsavers’ process for assessing whether the mass drug administration programmes it supports were successfully reaching their intended recipients and the charity’s "stand-out record of transparency".
A spokeswoman for Sightsavers said that GiveWell had told the charity it would be recommending that Good Ventures, the San Francisco-based foundation that works closely with GiveWell to determine how to spend its money effectively, give it initial support of about $2.9m, or £2.3m.
The spokeswoman said GiveWell’s recommendation had the potential to motivate and attract new donors to Sightsavers.
Caroline Harper, chief executive of the charity, said in a statement: "Our neglected tropical disease programmes, which include deworming and treating several disabling parasitical infections, are incredibly cost-effective.
"We are very excited to have been rated so highly by GiveWell. Working with it will allow us to have even greater impact for affected communities in Africa – both by scaling up existing programmes and expanding our reach with new ones."
Sightsavers and the Malaria Consortium, which works to control the disease, appeared on the list for the first time this year. The Against Malaria Foundation and the Schistosomiasis Control Initiative, which focuses on an infection, also known as bilharzia, caused in the developing world by a parasitic worm, have both been on the list since 2011, with the exception of one year when AMF did not feature.
Rob Mather, founder and chief executive of AMF, told Third Sector earlier this year that being on the list led to more than £35m being donated to the charity over the past five years, including a £16m donation in December from Good Ventures.
When GiveWell temporarily withdrew its endorsement in 2013, the charity's income fell from £5m to £3m, although it was reappointed to the list the following year.
SCI, a non-profit initiative that is housed at Imperial College London, used to receive all its funding from governments and foundations and had no voluntary income before being recognised by GiveWell. It now receives several million a year, which its director Alan Fenwick attributes to the evaluator’s backing.
For GiveWell's full report on Sightsavers visit http://www.givewell.org/charities/sightsavers.