The Eye Flashcards
Sclera
Tough outer coating, that supports and protects the eye
Cornea
Transparent outer layer at the front, that refracts light as it enters the eye
Retina
Contains light receptive cells, that converts it to electrical signals
Iris
Controls the diameter of the pupil
Pupil
Allows light to pass through
Lens
Focuses the light on the retina
Ciliary muscles and suspensory ligaments
Controls the shape of the lens
Optic Nerve
Carries the impulse from the retina to the brain
Accommodation
The process of changing the shape of the lens to focus on near or distant objects
The Eye focusing on near objects
The ciliary muscles contracts
The suspensory ligaments loosen
The lens becomes thicker and rounder
Refracts light rays strongly
The Eye focusing on distant objects
The ciliary muscles relax
The suspensory ligaments are pulled tight
The lens becomes thin
So light rays are refracted less
The Eye in bright light
Constricted
Circular muscles contract
Radial muscles relax
To let less light in
The Eye in dim light
Dilated
Circular muscles relax
Radial muscles contract
To let more light in
Myopia (short-sighted: can see close objects)
Rays are focused before the retina due to a long eye, or a lens that is too curved
Fix: concave lens
Hyperopia (long-sighted: can see far objects)
Rays are focused after the retina due to a short eye, or a flat lens
Fix: convex lens
