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MODHIII - Unit 3 > Vision > Flashcards

Flashcards in Vision Deck (33)
1

Presbyopia

- diminished ability to focus on near objects due to old age
- EVERYONE has this when they get old

2

Focusing the light on the retina

- mostly done by cornea
- lens does fine adjustment

3

Aqueous humor: synthesis & removal

- synthesized by ciliary epithelium
- removal through trabecular meshwork

4

Glaucoma

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

5

Sympathetic nervous system effect on pupil

Dilation via radial dilator muscles

6

Parasympathetic nervous system effect on pupil

constriction via pupillary sphincter

7

Efferent nerve defects

- anisocoria: unequal pupils

8

Afferent nerve defects

- pupils are always EQUAL

9

Cataract effect on pupil response to light

- none
- media opacities do not affect pupil response to light

10

Result of injury to sympathetic fibers to eye

Horner syndrome

11

Horner Syndrome

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

12

Sodium channels during darkness

- open
- depolarized membrane

13

Sodium channels during light

- closed
- hyperpolarized membrane

14

Phototransduction

- cascade of reactions that happen in the photoreceptors
**light--rhodopsin--transducin--phosphodiesterase--less cGMP--sodium channels close--graded HYPERpolarization**

15

What type of protein is rhodopsin

G-protein-coupled receptor

16

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

- vitamin A derivative (11-cis retinal)

17

Result of light hitting rhodopsin

- isomerization of 11-cis retinal to all trans retinal

18

Visual cycle

- conversion of trans retinal back to 11-cis retinal
- occurs outside photoreceptor cell in retinal pigment epithelium (RPE)

19

Photoreceptor surface turn over

- RPE allows turnover of entire photoreceptor surface every 10 days

20

Conversion of light to neurological impulse

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

21

Graded potential neurons

- photoreceptor and bipolar cell

22

Action potential neuron

ganglion cells

23

Retina blood supply

- derived from ophthalmic artery: retinal vessels, choroidal vessels

24

Age related macular degeneration

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

25

Retinal vasculature injury causes

- diabetic retinopathy
- atherosclerotic disease

26

Choroidal circulation injury causes

- age related macular degeneration (neovascularization)

27

Area bounded by temporal vascular arcades

Macula

28

Fovea

point of fixation in the center of the macula

29

Altinudal defects

- suggest disease inside the eye

30

Unilateral field defects

suggest disease anterior to the chiasm

31

Bitemporal field defects

suggest disease at the chiasm

32

Homonymous field defects

suggest disease behind the chiasm

33

Motor control of the eye

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