What term describes the line of sight going through the fovea?

• A. Primary visual direction
• B. Secondary visual direction
• C. Tertiary visual direction
• D. Central visual axis

Answer: (A)

The line of sight that passes through the fovea is called the primary visual direction. When the eye fixates, the image of the target falls on the fovea—the region of highest visual acuity—so the line from the pupil through the fovea represents the primary direction of gaze. This serves as the standard reference for where the eye is looking and for describing alignment in binocular vision. The other terms describe lines that would pass through nonfoveal retinal areas (secondary or tertiary visual directions), which are relevant for eccentric fixation or parafoveal vision. The central visual axis, meanwhile, refers to the optical or geometric axis of the eye itself, not specifically the fixation line through the fovea.