What does 'retinal focus' refer to?

Retinal focus refers to the specific point where light rays converge on the retina. This is crucial for clear vision, as it determines where an image is sharply projected within the eye. When light enters the eye, it passes through the cornea and lens, which bend and focus the light onto the retina. If the light rays do not converge precisely on the retina, it can result in blurred vision, indicating that proper focus is vital for optimal sight.

The other options, while related to aspects of vision and eye anatomy, do not accurately define retinal focus. The distance from the lens to the retina pertains to the anatomical space rather than the functional aspect of how light is focused. Clarity of vision relates to overall visual acuity and quality, which results from proper retinal focus but does not define the term itself. The strength of light at the retina speaks to illumination rather than the point of convergence of light rays.