Human Eye (Short Notes)

Ciliary Muscles

• Muscles that control the movement of the eyelids.

• Muscles attached to the lens that adjust its shape for focusing.

• Muscles responsible for the production of tears.

• Muscles that regulate the size of the pupil.

Retina

• Light-sensitive layer at the back of the eye; contains rods for dim light and cones for color; converts light into electrical signals.

• Outer layer of the eye that protects it from dust and debris.

• Part of the eye responsible for focusing light onto the lens.

• Fluid-filled space in the front of the eye that helps maintain its shape.

Image formation in Hypermetropia

• Image forms in front of the retina.

• Image forms on the retina.

• Image forms behind retina.

• Image forms at the cornea.

Yellow Spot (Fovea)

• A small region on the retina with maximum rod concentration.

• A small region on the retina with maximum cone concentration.

• A part of the eye responsible for peripheral vision.

• A region that provides the least clear vision.

Stars Twinkle but Planets Don’t

• Stars twinkle because they are closer to Earth than planets.

• Planets twinkle due to atmospheric refraction like stars do.

• Stars are point sources and twinkle due to atmospheric refraction, while planets are extended sources, so their twinkling is averaged out.

• Planets do not twinkle because they are always stationary in the sky.

Correction for Hypermetropia

• Corrected using concave lens.

• Corrected using convex lens.

• Corrected using cylindrical lens.

• Corrected using no lens.

Functioning of the Eye

• The eye acts like a camera.

• The eye only detects color.

• The eye does not require light to function.

• The eye is primarily used for hearing.

Diagram of Hypermetropic Eye and Correction

• Illustrates the near point of a hypermetropic eye and correction using a convex lens.

• Shows the structure of a myopic eye and its correction.

• Depicts the effects of astigmatism on vision.

• Illustrates the process of cataract formation and treatment.

Dispersion

• Separation of white light into VIBGYOR (Violet, Indigo, Blue, Green, Yellow, Orange, Red).

• Mixing of colors to form white light.

• Reflection of light through a prism.

• Absorption of light by a colored object.

Functions of the Eye as a Whole

• Refraction of light to form images.

• Production of tears to keep the eye moist.

• Regulation of blood flow to the eye.

• Transmission of image signals to the brain.