The Human Eye

Question 1

Sclera

Answer 1

Tough white layer to resist punctures

Question 2

Cornea

Answer 2

Bends image, no blood vessels, 90% of focus power

Question 3

Iris

Answer 3

Circular muscle, controls pupil size, coloured part of eye

Question 4

Ciliary Muscles

Answer 4

Controls lens shape for focusing

Question 5

Choroid

Answer 5

Blood rich, dark inky layer to darken eyeball

Question 6

Lens

Answer 6

Focuses & inverts image, 10% of focus power

Question 7

Aqueous Humour

Answer 7

Clear fluid between cornea and lens, fluid is renewed every half an hour, nourishes cornea

Question 8

Vitreous Humour

Answer 8

Clear pressurized fluid to maintain eyeball shape

Question 9

Retina

Answer 9

Contains photoreceptors (rods & cones)

Question 10

Fovea Centralis

Answer 10

90% of cones, colour vision, central & clarity/ sharpness of vision

Question 11

Blind spot

Answer 11

Where optic nerve leaves the eye, no room for photoreceptors

Question 12

Optic nerve

Answer 12

Contains 1 million axon to occipital lobe

Question 13

Rods

Answer 13

Peripheral located, black & white contrast, motion sensitive, night vision, 1 kind, pigment= Rhodopsin

Question 14

Cones

Answer 14

Centrally located, colour sensitive, clarity & detail, bright light (day), 3 kinds (RBG), Pigment=Iodopsin

Question 15

Eyebrows

Answer 15

Deflect water & debris

Question 16

Blinking

Answer 16

Keeps eye moist

Question 17

Glaucoma

Answer 17

Issue with Aqueous Humour & Retina
Due to increased fluid pressure in the aqueous humour. Blockage of drainage ducts causing pressure to rise.

Question 18

Cataract

Answer 18

Issue with lens
Lens becomes cloudy as we age
Light & images do not pass clearly
Lens proteins have been denatured due to UV light exposure

Question 19

Astigmatism

Answer 19

Issue with cornea
Normal cornea is smooth & symmetrical
Sometimes cornea adopts an irregular shape
Light entering the eye gets scattered rather than focused on the retina

Question 20

Myopia (nearsightedness)

Answer 20

Issue with cornea, lens & retina
Close up objects are seen well
Far away object are blurred
Image comes into focus in front of the fovea rather than on it.

Question 21

Hyperopia (farsightedness)

Answer 21

Issues with cornea, lens & retina
Far away objects are seen well
Close up object are blurred
Image is unable to focus on fovea. Focuses behind the eye