Original sentence: This section is based on Glanville (1933)
Edited sentence: He built on the binocular vision work of Ptolomy and discovered that objects lying on a line passing through the fixation point resulted in single images, while objects a reasonable distance from this line resulted in double images.It was only later that this line was shown to actually be a circlular plane surrounding the viewer's head.The horopter was first discovered in the eleventh century by Persian scholar Ibn al-Haytham, known to the west as "Alhazen"