Editing Leonhard Euler (section)

===Eyesight deterioration===
Euler's eyesight worsened throughout his mathematical career. In 1738, three years after nearly dying of fever,{{sfn|Gautschi|2008|p=6}} he became almost blind in his right eye. Euler blamed the [[cartography]] he performed for the St. Petersburg Academy for his condition,<ref name="blindness" /> but the cause of his blindness remains the subject of speculation.<ref name="righteye" /><ref name="bullock"/> Euler's vision in that eye worsened throughout his stay in Germany, to the extent that Frederick called him "[[Cyclopes|Cyclops]]". Euler said of his loss of vision, "Now I will have fewer distractions."<ref name="blindness" /> In 1766 a [[cataract]] in his left eye was discovered. Though [[Couching (ophthalmology)|couching of the cataract]] temporarily improved his vision, complications rendered him almost totally blind in the left eye as well.<ref name="volumes"/> His condition appeared to have little effect on his productivity. With the aid of his scribes, Euler's productivity in many areas of study increased;{{sfn|Gautschi|2008|pp=9–10}} in 1775, he produced, on average, one mathematical paper per week.<ref name="volumes" />