There are many sources which say that Euler produced, on average, one mathematical paper every week in the year $1775$. Some even say he produced almost half his total works despite the total blindness.
I can't seem to find much works after $1770$, on the page linked it says for the square root of -1 (1777) and Cauchy-Riemann equations in $1777$ does anyone have some references to Euler's works after he got blind?
Euler indeed produced much of his work when he was blind, as can be seen from the Euler archive. The blindness developed gradually: first he lost sight in one eye, several years later in another. Euler himself joked: when he became completely blind he said that this is even better for his research, because fewer things will distract him. Euler was assisted by several secretaries, including his own children and grandchildren. Source: William Dunham, Euler: The Master of Us All (MAA, 1999).
