The Eye Flashcards
(22 cards)
The Sclera
• Protects and supports the eyeball
Cornea
•Bends light rays into the eye
Choroid
• Absorb scattered light and contains blood vessels
Iris
• Regulates the amount of light that enters the eye
Pupil
•Is the opening for light to enter the inner eye
Ciliary muscles
•Changes the shape of the lens in order to focus
Rods
- Photoreceptors that are sensitive to dim light
* used more often at night
Cones
- Photo receptors that are sensitive to different wavelengths of light (colour vision)
- used more during the day
- greater visual acuity
Fovea centralis
•Contains a high density of cones, and provides acute vision
Lens
• Focusses light rays onto the fovea centralis
Humours
• Support the eyeball, with the pressure of the fluids they contain
Optic nerve
• Transmit sensory information to the brain
Blindspot
- Area of no photo sensitive cells
* Where the retina and optic nerves come into contact
Accommodation reflex of close up
- Pupils constrict in attempt to bring the objects into focus
- Lens thickened to see up close objects
Accommodation reflex from a distance
- Pupil dilated letting in as much light as possible to focus
- Lens thin out to see long distance
Light passes through which parts of the eyes?
•(respectively) Light passes through the cornea, pupil, aqueous humour,lens, vitreous humour (gel like substance) then projects onto the retina (at the back of the eye)
Eye disorders
- Nearsighted
- farsighted
- astigmatism
- glaucoma
- cataract
Nearsightedness
- eye is too short
- image is focused before the retina
- cure concave lens
Farsightedness
- eye is too long
- image focuses after the retina
- cure: convex lens
Astigmatism
- Irregular curvature of lens
- blurred vision
- cure: glasses or surgery
Glaucoma
- Buildup of fluid and eyes
- Cut off blood to retina = blindness
- cure: eye drops
Cataract
- Lens of cornea clouds
- Block light to retina = blindness
- cure: surgery to replace lens
