The charity evaluator praised Sightsavers for its work treating children for parasitic infections, known as deworming.
Professor Hawking spoke at Sightsavers’ event to mark the one billionth treatment for neglected tropical diseases: watch the full video of his speech here.
The physicist will lead global celebrations to mark the one billionth treatment that Sightsavers and partners have delivered to tackle NTDs.
The billionth treatment was administered on Thursday 16 November to a seven-year-old girl named Dorcas, who was at risk of NTDs in Kaduna State, Nigeria.
Trachoma is easily transmitted from person to person, so good hygiene is vital to prevent the disease spreading.
Two more areas and more than a million people in the country have met the World Health Organization criteria for elimination of the disease.
Sightsavers is trialling an alternative strategy: rather than treating entire populations, the aim is to test residents first to see if they have the disease.