Judi Dench suffers from age-related macular degeneration (AMD).
The fifth season of The Crown, featuring Imelda Staunton as Queen Elizabeth II, is set to be released on 9 November.
Kenneth Branagh read his script for Judi Dench when he offered her the role of Buddy’s grandmother.
Maggie Q, Sir Paul McCartney and Kat Graham also got involved.
The duo appeared in the new film version of Blithe Spirit.