Vision

Question 1

Presbyopia

Answer 1

• diminished ability to focus on near objects due to old age

- EVERYONE has this when they get old

Question 2

Focusing the light on the retina

Answer 2

• mostly done by cornea

- lens does fine adjustment

Question 3

Aqueous humor: synthesis & removal

Answer 3

• synthesized by ciliary epithelium

- removal through trabecular meshwork

Question 4

Glaucoma

Answer 4

• decreased aqueous humor outflow leading to increased intraocular pressure, which injures the optic nerve
• second most common cause of blindness

Question 5

Sympathetic nervous system effect on pupil

Answer 5

Dilation via radial dilator muscles

Question 6

Parasympathetic nervous system effect on pupil

Answer 6

constriction via pupillary sphincter

Question 7

Efferent nerve defects

Answer 7

• anisocoria: unequal pupils

Question 8

Afferent nerve defects

Answer 8

• pupils are always EQUAL

Question 9

Cataract effect on pupil response to light

Answer 9

• none

- media opacities do not affect pupil response to light

Question 10

Result of injury to sympathetic fibers to eye

Answer 10

Horner syndrome

Question 11

Horner Syndrome

Answer 11

• anisocoria: small pupil on affected side
• ptosis: droopy eyelid on affected side
• diminished sweating on affected side

Question 12

Sodium channels during darkness

Answer 12

• open

- depolarized membrane

Question 13

Sodium channels during light

Answer 13

• closed

- hyperpolarized membrane

Question 14

Phototransduction

Answer 14

• cascade of reactions that happen in the photoreceptors

* *light–rhodopsin–transducin–phosphodiesterase–less cGMP–sodium channels close–graded HYPERpolarization**

Question 15

What type of protein is rhodopsin

Answer 15

G-protein-coupled receptor

Question 16

In oder for rhodopsin to be sensitive to light it needs what

Answer 16

• vitamin A derivative (11-cis retinal)

Question 17

Result of light hitting rhodopsin

Answer 17

• isomerization of 11-cis retinal to all trans retinal

Question 18

Visual cycle

Answer 18

• conversion of trans retinal back to 11-cis retinal

- occurs outside photoreceptor cell in retinal pigment epithelium (RPE)

Question 19

Photoreceptor surface turn over

Answer 19

• RPE allows turnover of entire photoreceptor surface every 10 days

Question 20

Conversion of light to neurological impulse

Answer 20

• minimum of three neurons: photoreceptor, bipolar cell, ganglion cell
• light stimulus on retina turns into neurological impulse

Question 21

Graded potential neurons

Answer 21

• photoreceptor and bipolar cell

Question 22

Action potential neuron

Answer 22

ganglion cells

Question 23

Retina blood supply

Answer 23

• derived from ophthalmic artery: retinal vessels, choroidal vessels

Question 24

Age related macular degeneration

Answer 24

• accumulation of extracellular lipids (lipofuscin) and protein deposits (drusen) beneath RPE
• most common cause of blindness

Question 25

Retinal vasculature injury causes

Answer 25

• diabetic retinopathy

- atherosclerotic disease

Question 26

Choroidal circulation injury causes

Answer 26

• age related macular degeneration (neovascularization)

Question 27

Area bounded by temporal vascular arcades

Answer 27

Macula

Question 28

Fovea

Answer 28

point of fixation in the center of the macula

Question 29

Altinudal defects

Answer 29

• suggest disease inside the eye

Question 30

Unilateral field defects

Answer 30

suggest disease anterior to the chiasm

Question 31

Bitemporal field defects

Answer 31

suggest disease at the chiasm

Question 32

Homonymous field defects

Answer 32

suggest disease behind the chiasm

Question 33

Motor control of the eye

Answer 33

• abducens (VI): lateral rectus
• trochlear (IV): superior oblique
• oculomotor (III): all other eye muscles
• **LR6SO4