Galileo became completely blind in 1638. By then, he was in his seventies and living under house arrest at Arcetri near Florence.
Galileo's loss of sight developed gradually rather than happening in a single sudden incident. His right eye had failed earlier, and his remaining vision deteriorated until he was completely blind in 1638. Despite this disability, he continued working with assistance and completed important scientific writing.
That same year, Two New Sciences was published in Leiden. The book summarized Galileo's investigations of motion and the strength of materials and is regarded as his final major work. His blindness did not mark the end of his intellectual activity: assistants helped him communicate and record ideas, while visitors and correspondents kept his scientific work circulating. Galileo died in 1642, four years after becoming fully blind.