Unit A - Structures & disorders of the Eye Flashcards
What is the Sclera and what does it do? (4)
- Thick white fibrous layer
- outer layer
- maintians shape
- Protects eye
What is the Cornea and what does it do?
- Refracts Bends light into the pupil
What is the Choroid Layer and what does it do? (3)
- Contains blood vessels & pigmented granules
- Pigmented granules (making it black)
- Bends light
What is the Iris and what does it do? (2)
- Thing circular & radial muscles
- Constrict/dialate to let light in.
influenced by the parasympathetic and sympathetic nervous system.
What is the pupil and what does it do? (1)
- Hole in the eye
What is the Lens and what does it do? (3)
- biconvex
- refracts light
- inverts the image
What is accommodation?
Changes to lens shape to focus the image.
What is the shape of the lens for looking at close/far objects?
Far = Flat lens
Close - Curved lens
What is the Retina and what does it do? (1)
- Made of rods and cones
What is the blind spot and what does it do? (2)
- location on the retia where the optic nerve exists
- Photoreceptors are absent here
What are rods and what does it do? What is one flaw? (3)
- Respond to low intensity light
- Discriminate between shades of grey
- Unable to provide detailed vision
What is rhodopsin made of?
Composed of Vitamin A derivative retinal and protien opsin
How does rhodopsin respond to different types of light?
Darkness –> rhodopsin stimulates release of inhibitors preventing impulses in the eye
Dim light –> Rhodopsin splits –> inhibitory neurotransmitters are no longer released
Bright light –> rhodopsin breaks down too quickly
What are cones and what does it do? (2)
- require high intensity light
- detect red, green, and blue
What is the Fovea centralis and what does it do? (2)
- concentrated area of cones
- where the eye focuses on
What are the steps in vision?
Light → conea → Aqueous humor→ lens→vitreous humor→photoreceptor (retina) → Optic nerve → Occiptal lobe.
What are cataracts?
How do you treat them?
Clouding of lens
Treatment: Surgery
What is a Glaucoma?
Pressure build up in the eye that damages the optic nerve.
Treatment: eye drops, laser therapy, and eye surgery.
What is astigmatism?
An abnormally shaped cornea causing blurred vision
Treatment: Corrective lenses and eye surgery.
What is Myopia?
Able to focus up close, and difficulty focus sign on far object. Caused by a long eye.
Treatment: corrective concave lenses or laser surgery
focuses in front of retina
What is Hyperopia?
Able to focus object that are far, difficulty focusing on objects close. Caused by a shortend eye
Focuses in behind retina
