This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and refraction, Subject name: Ophthalmology
[{'content': 'Visual axis is - \nSelect and explain. \nA. Center of cornea to retina, B. Object to fovea, C. Center of lens to cornea, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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', 'role': 'assistant'}]