Optics and Vision

Function of the Lens in the Human Eye

• The lens focuses light onto the retina, allowing for clear images.
• It adjusts its shape (accommodation) to focus on objects at varying distances.

Resemblance of the Human Eye to a Camera

• Both systems have a lens that focuses light onto a surface (retina vs. image sensor).
• The aperture in a camera is analogous to the pupil, controlling light entry.
• The retina functions like film or a digital sensor, capturing images.

Enabling Vision of Colorful World

• The presence of cone cells in the retina allows for the perception of color.
• There are three types of cones sensitive to different wavelengths (red, green, blue).
• Color perception results from the brain interpreting signals from these cones.

Function of the Cornea in the Human Eye

• The cornea is the clear, outer layer that protects the eye and aids in light refraction.
• It contributes to the eye's overall focusing power, providing about two-thirds of the eye's total optical power.
• The cornea is avascular, receiving nutrients from tears and the aqueous humor.

Lenses in Spectacles and Vision Correction

• Spectacle lenses correct refractive errors by altering the direction of incoming light.
• Concave lenses (negative) are used for myopia (nearsightedness), diverging light rays.
• Convex lenses (positive) assist with hyperopia (farsightedness), converging light rays to improve focus on the retina.