Final answer:
Emmetropia is the state where the eye's optical system can form a sharp image directly on the retina without needing any refractive power adjustments. Accomodation is the eye's adjustment process for close vision.
Step-by-step explanation:
When light reaches the retina without any need for refractive power, it is because the light is entering the eye at a refractive state known as emmetropia. In this state, the eye is perfectly focused for distant objects, meaning that the optical system of the eye is able to form a sharp image directly on the retina without the need for additional bending of light rays. However, when the eye must adjust its focal length and power to focus on close objects, this process is known as accommodation.