Opthamology

Question 1

What is refraction?

Answer 1

The bending of light from one optical medium to another

Question 2

What’re the refractive media in the eye?

Answer 2

Cornea
Aqueous humour
Lens
Vitreous humour

Question 3

What makes accommodation happen?

Answer 3

Cilliaris

Question 4

What is accommodation?

Answer 4

The capacity to change focus from distance objects to close objects

Question 5

What 3 things happen simultaneously in accommodation?

Answer 5

Lens thickens
Pupils constrict
Eyes converge

Question 6

What muscle causes the lens to thicken?

Answer 6

Cilliaris causing the ciliary muscle to contract

Question 7

What causes the pupil to constrict?

Answer 7

Constrictor pupillae

Question 8

What causes the eyes to intort?

Answer 8

Medial rectus of both sides contact

Question 9

In which refractive error is the eyeball too long?

Answer 9

Myopia

Question 10

What do hyperopes use their accommodation for?

Answer 10

Use all their accommodative power to see far away so they run out of accommodative power to see up close

Question 11

What is astigmatism?

Answer 11

Non spherical curvature of the cornea or lens

Question 12

S+S of astigmatism

Answer 12

Hazy image

2 images being formed

Question 13

What type of contact lenses do astigmatic people wear?

Answer 13

Toric lenses

Question 14

What’s presbyopia?

Answer 14

Longsightedness of old age

Question 15

What’s emmetropia?

Answer 15

Perfect vision

Question 16

What does CYL mean?

Answer 16

The power needed to correct astigmatism

Question 17

What causes presbyopia?

Answer 17

Lens gets less mobile due to the ciliary muscle not being able to change as it used to

Question 18

what is rhodopsin?

Answer 18

A protein

Question 19

What happens when light hits 11 cis-retinal?

Answer 19

Bond becomes straight and becomes 11 trans retinal

Question 20

What can vitamin A deficiency lead to?

Answer 20

Bitot’s spots in conjunctiva
Cornelia ulceration
Corneal melting
-leads to further opacification of the cornea

Question 21

Epithelium type in cornea

Answer 21

Stratified squamous non-keratinised

Question 22

Where’s bowman’s membrane?

Answer 22

Basement membrane of corneal epithelium

Question 23

How is transparency maintained in the cornea?

Answer 23

Regular arrangement of collagen in stroma
No blood vessels
Endothelium has a pump which actively keeps the aqueous humour out

Question 24

Why is the avascularity of the cornea an advantage in performing corneal graft surgery?

Answer 24

Less chance of it being rejected ad there’s less foreign antigens present
It’s an immune privileged site

Question 25

The 10 layers of the retina and choroid?

Answer 25

◦ 10=inner limiting membrane 
	◦ 9=nerve fibre layer
	◦ 8=ganglion cell layer
	◦ 7=inner plexiform layer
	◦ 6=inner nuclear layer
	◦ 5=outer plexiform layer
	◦ 4=outer nuclear layer 
	◦ 3=outer limiting membrane 
	◦ 2=layer of rods and cones
	◦ 1=pigment of epithelial layer

Question 26

How do the outer layers of the retina get blood?

Answer 26

By diffusion

Question 27

How do the inner layers of the retina get blood?

Answer 27

Branches of the retinal artery

Question 28

What’s lens opacification more commonly known as?

Answer 28

Cataracts

Question 29

4 functions of tear film

Answer 29

Keep the cornea moist, prevent it from drying out
Washes away particulate from foreign bodies
Antibodies and lysosomes to kill microbes
Smooths outer layer of the cornea providing smooth surface for refraction

Question 30

What’re the 3 layers of the tear film?

Answer 30

Layer 1=mucinous layer
Later 2=aqueous layer
Later 3=oily layer

Question 31

What’s the innervation of tear secretion into the conjunctival sac?

Answer 31

Parasympathetic 7

Question 32

What happens to the tear film when the eyes are open?

Answer 32

Aqueous layer begins to evaporate and oily layer comes close to mucin layer
When these 2 layers touch each other the tear film breaks up which stimulates further blinking