Visual axis is -

Optical axis :- Axis passing through centeres of cornea, lens to retina Visual axis :- line passing through fixation point to fovea. The visual axis is one of the axes through the eye that has been defined and used by optical equipment designers and people who work with the physics, specifically the optics, of the eye - rather than by people concerned with the biology and physiology of human vision. The visual axis is not a physical feature of the eye and so cannot be identified by dissection or by any physical imaging techniques. A simple definition of the visual axis is: " A straight line that passes through both the centre of the pupil and the centre of the fovea". There is also a stricter definition (in terms of nodal points) which is impoant for specialists in optics and related subjects. Reference : Sunita Agrawal 2nd edition ,page422