List the structures (in order) in the eye through which light directly passes to reach the retina.
The correct answer and explanation is:
Correct Answer:
The correct order of eye structures that light passes through to reach the retina is:
- Cornea
- Aqueous humor
- Pupil (through the Iris)
- Lens
- Vitreous humor
- Retina
Explanation:
Light entering the human eye must pass through several transparent structures before it reaches the retina, where photoreceptor cells detect it and initiate the process of vision.
- Cornea: The journey begins at the cornea, the clear, dome-shaped outer layer that covers the front of the eye. The cornea bends (refracts) light to help it focus properly.
- Aqueous Humor: After the cornea, light travels through the aqueous humor, a clear fluid found in the anterior chamber (between the cornea and the iris). This fluid maintains eye pressure and provides nutrients.
- Pupil and Iris: Light then passes through the pupil, the opening in the center of the iris. The iris is the colored part of the eye that adjusts the size of the pupil to control how much light enters.
- Lens: Next, light enters the lens, a transparent, flexible structure that further focuses the light onto the retina. The lens changes shape through the action of the ciliary muscles, enabling us to focus on objects at different distances (a process called accommodation).
- Vitreous Humor: After the lens, light travels through the vitreous humor, a clear, gel-like substance that fills the large chamber in the center of the eye. This helps maintain the shape of the eyeball and transmits light to the back.
- Retina: Finally, the light reaches the retina, a thin layer of tissue at the back of the eye that contains photoreceptor cells (rods and cones). These cells convert the light into electrical signals, which are then sent to the brain via the optic nerve for interpretation.
Each structure plays a crucial role in ensuring that light is accurately focused on the retina to produce clear vision.