Over time it was found that if a line was drawn through the posterior apex of the crystalline lens at the visual angle of a distant object, then it would point to the image location on the retina, even for very large angles.
As time progressed, it became evident that drawing a line through the back of the lens, at the visual angle of a distant object, would always lead to the location of the image on the retina, regardless of how wide the angle was.