Unit A - Structures & disorders of the Eye

Question 1

What is the Sclera and what does it do? (4)

Answer 1

• Thick white fibrous layer
• outer layer
• maintians shape
• Protects eye

Question 2

What is the Cornea and what does it do?

Answer 2

• Refracts Bends light into the pupil

Question 3

What is the Choroid Layer and what does it do? (3)

Answer 3

• Contains blood vessels & pigmented granules
• Pigmented granules (making it black)
• Bends light

Question 4

What is the Iris and what does it do? (2)

Answer 4

• Thing circular & radial muscles
• Constrict/dialate to let light in.

influenced by the parasympathetic and sympathetic nervous system.

Question 5

What is the Sclera and what does it do? (1)

Answer 5

• Hole in the eye

Question 6

What is the Lens and what does it do? (3)

Answer 6

• biconvex
• refracts light
• inverts the image

Question 7

What is accommodation?

Answer 7

Changes to lens shape to focus the image.

Question 8

What is the shape of the lens for looking at close/far objects?

Answer 8

Far = Flat lens
Close - Curved lens

Question 9

What is the Retina and what does it do? (1)

Answer 9

• Made of rods and cones

Question 10

What is the blind spot and what does it do? (2)

Answer 10

• location on the retia where the optic nerve exists
• Photoreceptors are absent here

Question 11

What are rods and what does it do? What is one flaw? (3)

Answer 11

• Respond to low intensity light
• Discriminate between shades of grey
• Unable to provide detailed vision

Question 12

What is rhodopsin made of?

Answer 12

Composed of Vitamin A derivative retinal and protien opsin

Question 13

How does rhodopsin respond to different types of light?

Answer 13

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

Question 14

What are cones and what does it do? (2)

Answer 14

• require high intensity light
• detect red, green, and blue

Question 15

What is the Fovea centralis and what does it do? (2)

Answer 15

• concentrated area of cones
• where the eye focuses on

Question 16

What are the steps in vision?

Answer 16

Light → conea → Aqueous humor→ lens→vitreous humor→photoreceptor (retina) → Optic nerve → Occiptal lobe.

Question 17

What are cataracts?

How do you treat them?

Answer 17

Clouding of lens

Treatment: Surgery

Question 18

What is a Glaucoma?

Answer 18

Pressure build up in the eye that damages the optic nerve.

Treatment: eye drops, laser therapy, and eye surgery.

Question 19

What is astigmatism?

Answer 19

An abnormally shaped cornea causing blurred vision

Treatment: Corrective lenses and eye surgery.

Question 20

What is Myopia?

Answer 20

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

Question 21

What is Hyperopia?

Answer 21

Able to focus object that are far, difficulty focusing on objects close. Caused by a shortend eye

Focuses in behind retina