fovea centralis

The fovea centralis of the human retina is the seat of most acute vision, and in the fovea centralis there are no rods.

This central part is called the fovea centralis and is the point of acutest vision.

In the fovea centralis—the point of the retina on the optical axis of the eye—is a slight depression much thinner than the remainder of the retina and this is inhabited chiefly by cones.

It is exactly that line which joins the point fixed with the centre of the fovea centralis.

Therefore the area in the squinting eye that corresponds to the fovea centralis of the fixing eye must be more extensive in the horizontal than in the vertical direction.