Eye Anatomy and Light Refraction

Flashcards covering the topics of eye anatomy, light, and refraction of light.

Visible Light

Packets of energy (photons) that travel in wavelike fashion at high speeds.

Light and Color Perception

The color perceived is a reflection of a particular wavelength; white reflects all colors, and black absorbs all colors.

Light Path

Light travels in straight lines and is blocked by non-transparent objects; its speed changes when passing between mediums of different densities.

Refraction

Bending of light rays due to a change in speed when light passes from one transparent medium to another at an oblique angle.

Convex Lens

A lens thicker in the center than at the edges.

Concave Lens

A lens thicker at the edges than in the center.

Focal Point

The single point where light rays converge after passing through a convex lens.

Focal Distance

The distance between the lens and the focal point.

Retinal Image

Image formed at the focal point is upside-down and reversed from left to right; the brain corrects for this.

Light Path into the Eye

Cornea → aqueous humor → lens → vitreous humor → neural layer of retina → photoreceptors.

Refraction Points in the Eye

Light is refracted three times: entering cornea, entering lens, and leaving lens.

Cornea Refractory Power

The cornea provides the majority of the eye's refractory power, but it is constant and cannot change focus.

Lens Adjustment

The lens adjusts its curvature for fine focusing, allowing focus for both distant and close vision.

Emmetropia

Normal eye state where a faraway object at infinity is in sharp focus with the eye lens in a neutral or relaxed state.

Accommodation of the Lens

Changing lens shape to increase refraction (focusing), facilitated by ciliary muscle contraction.

Accommodation Pupillary Reflex

Constriction of pupils to prevent most divergent light rays from entering the eye.

Convergence of the Eyeballs

Medial rotation of eyeballs causing convergence of eyes toward the object being viewed, accomplished by medial rectus muscles.

Myopia

Nearsightedness; eyeball is too long, causing the focal point to be in front of the retina, corrected with a concave lens.

Hyperopia

Farsightedness; eyeball is too short, causing the focal point to be behind the retina, corrected with a convex lens.

Astigmatism

Unequal curvatures in different parts of the cornea or lens, corrected with cylindrically ground lenses or laser procedures.

Presbyopia

Loss of accommodation over age 50.