Final answer:
The retina, lens, and pupil are crucial for vision, with the retina detecting light, the lens focusing it, and the pupil controlling light entry. The fovea provides sharp detail, and the optic nerve transmits information to the brain.
Step-by-step explanation:
Three critical parts of the human eye that are essential for vision include the retina, which detects light and converts it into neural signals; the lens, which adjusts its shape to focus light onto the retina; and the pupil, which regulates the amount of light entering the eye. The fovea is the part of the retina with the highest acuity for detecting fine details. The optic nerve carries visual information from the eye to the brain, completing the process of seeing.