Vision 1

Question 1

What are the three layers of the eyeball wall?

Answer 1

1) Sclera and cornea (outer)
2) Uvea
3) Retina (inner)

Question 2

What are the three parts of the Uvea?

Answer 2

Choroid (posterior)
Ciliary body (middle)
Pupil (anterior)

Question 3

What are the functions of the sclera?

Answer 3

• protect eye from trauma
• maintains intraocular pressure
• attachment site of extra-ocular muscles

Question 4

What is the definition of glaucoma?

Answer 4

When intra-ocular pressure is high enough to cause damage

Question 5

What is the function of the choroid?

Answer 5

• supplies nutrients and O2 to outer retina (highly vascular)
• pigment absorbs light

Question 6

What is macular degeneration?

Answer 6

• age related condition where macula (centre of retina which is used for central vision) breaks down
• causes blurry vision only in centre

Question 7

What is the pathophysiology of macula degeneration?

Answer 7

sheet of vascular tissue starts growing upward from the choroid and infringing on the macula part of the retina (which pushes the retina up)

Question 8

Define myopia and hypermetropia?

Answer 8

Myopia = short sighted 
hypermetropia = long sighted

Question 9

What causes myopia and hypermetropia?

Answer 9

Myopia - Light brought to a focus just before it reaches the retina usually due to having longer eyeballs
hypermetropia - light brought to focus just after the retina usually due to having shorter eyeballs

Question 10

What is astigmatism?

Answer 10

curvature in the cornea is steeper in one axis then the other resulting in distortion

Question 11

What is the function of the cornea?

Answer 11

focuses light (this is where most light refraction occurs)

Question 12

What are the five layers of the cornea?

Answer 12

• epithelium (constantly regenerated by stem cells)
• Bowmans capsule
• stroma
• descemets membrane
• endothelial cells (prevent over hydration of stroma)

Question 13

What is a corneal abrasion?

Answer 13

• scratch on the cornea
• will heal like a cut thanks to stem cell regeneration
• very painful and patient will be photosensitive

Question 14

How can you check for corneal abrasion?

Answer 14

apply orange fluorescent drop (fluorescein) to the eye then shine blue light
fluorescein will show up green on abrasion

Question 15

Can cornea be transplanted?

Answer 15

• can transplant all sections of cornea even half or only deeper layer if necessary
• will need topical eyedrops but no immunosuppressants

Question 16

What is the function of the iris?

Answer 16

constrict and dilate pupil

Question 17

What are the two muscles of the iris?

Answer 17

Sphincter pupillae (parasympathetic supply)
Dilator pupillae (sympathetic supply)

Question 18

What is Horners syndrome?

Answer 18

problem with sympathetic supply resulting in unopposed parasympathetic supply resulting in contraction only (pupil always small)

Question 19

What is the pathway of aqueous humour?

Answer 19

• produced in ciliary body
• moves into anterior chamber between iris and cornea
• travels out through trabecular pathway
• eventually into venous system
• Constantly being produced and drained

Question 20

What is the most common problem associated with aqueous humour?

Answer 20

Glaucoma caused by a blockage in pathway when travelling between lens and iris or increased resistance when entering trabecular pathway

Question 21

What is the functions of the ciliary body?

Answer 21

• produce aqueous humour

- accommodation (ciliary muscle contracts when focusing on near objects)

Question 22

What is presbyopia?

Answer 22

age related reduction in ability to accommodate (caused by lens stiffness)
- treated using varifocal glasses

Question 23

Where would you find vitreous humour?

Answer 23

posterior to the lens, attached to the retina

Question 24

What is posterior vitreous detachment?

Answer 24

• vitreous collapses in on itself (normal process) causing flashing lights and floaters in vision
• flashing lights will stop eventually but floaters last forever

Question 25

Why must you check the retina if patient presents with flashes/floaters?

Answer 25

if getting new floaters/flashing lights will need to check retina in case tear which allows for fluid to get through tear and cause retinal detachment

Question 26

What are the two layers of the retina?

Answer 26

Neural layer - Rods and cones Pigmented layer (both supplied by choroid)

Question 27

What aspects of vision are gathered by rods and cones and where are they each most concentrated?

Answer 27

``` Rods - light intensity - fovea (centre of macula) Cones - Colour - periphery of retina ```

Question 28

What is the optic disc?

Answer 28

area where axons from ganglion cells merge to form optic nerve

Question 29

What area of the retina is supplied by blood vessels seen in fundoscopy?

Answer 29

inner part of retina not deeper part (where pigmented and photoreceptors are)

Question 30

Why do you have a blind spot at your optic nerve?

Answer 30

There are no photoreceptors located there