NOTES ON HUMAN EYE

 

          The Human Eye – Notes

Structure of the Human Eye

The human eye is a complex organ responsible for vision. It consists of several key parts:

1. External Structures:

Sclera: The white outer layer that provides protection.

Cornea: The transparent front part that helps focus light.

Conjunctiva: A thin membrane covering the sclera and inside of the eyelids.

 2. Internal Structures:

Iris: The colored part of the eye that controls the size of the pupil.

Pupil: The black circular opening that regulates light entry.

Lens: A flexible, transparent structure that focuses light onto the retina.

Retina: A light-sensitive layer containing photoreceptor cells (rods and cones).

Optic Nerve: Transmits visual signals from the retina to the brain.

Vitreous Humor: A gel-like substance that maintains the shape of the eye.

Ciliary Muscles – Help in changing the shape of the lens for focusing.

          Functioning of the Eye

1. Light enters through the cornea and passes through the pupil.

2. The lens focuses the light onto the retina, forming an inverted image.

3. Rod cells detect low light, and cone cells detect color.

4. The optic nerve transmits signals to the brain, where the image is interpreted.

         Common Eye Defects

Myopia (Nearsightedness): Distant objects appear blurry due to the elongation of the eyeball. Corrected using concave lenses.

Hyperopia (Farsightedness): Close objects appear blurry due to a short eyeball. Corrected using convex lenses.

Astigmatism: Blurred vision due to an irregularly shaped cornea or lens.

Cataracts: Clouding of the lens, leading to vision impairment.

Glaucoma: Increased pressure in the eye, which can damage the optic nerve.

            Care for the Eyes

Eat a diet rich in vitamin A (found in carrots, spinach, and fish).

Protect eyes from UV light by wearing sunglasses.

Take regular breaks from screens to prevent eye strain.

Get regular eye check-ups to detect problems early.

The human eye is an essential sensory organ, and proper care helps maintain good vision 

          Functioning of the Eye

Light enters through the cornea and pupil.

The lens focuses the light onto the retina.

The retina converts light into electrical signals.

The optic nerve sends signals to the brain, which processes them into

 images

👊