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Year 2 LCRS Neurology > Eye > Flashcards

Eye Flashcards

1
Q

How are the lateral and medial borders of the eye anteriorly called?

A
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2
Q

What is the name of the white part of the eye?

A

It is the sclera

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3
Q

How is the space between the two eyelids anteriorly called?

A

It is called the palprebral fissure

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4
Q

How is the remainant of the 3rd eyelid in the human eye called?

A

Caruncula

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5
Q

Why do we produce tears?

A
  • Basal tears
    • Lubrication of eye
  • Relflex tears
    • in response to irritation
  • Emotional tears
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6
Q

What are the function of tear production?

A
  1. Smooth cornea-air surface –> O2 supply of cornea via oxgena in air
  2. Removal of debris
  3. Protection from infective agents
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7
Q

Explain the organisation of the tear film and respective function

A
  1. Mucous layer –> moisturise surface of cornea
  2. Aqueous part (secreted by lacrimal gland)
  3. superficial Lipid layer –> prevent evaporation
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8
Q

Explain the production and drainigae of tears

A
  • Produced by lacrimal gland (PNS stimmulation)
  • Absorbed medially via Punctum
  • Via canaliculi into the tear sac
  • And from there into tear duct –> nose
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9
Q

What is the conjunctiva?

A

Thin layer of tissue covering the outer layer of the eye (visible part+ inner parts of eyelids)

–> supplied by almost invisible blood vessels

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10
Q

What is the cornea?

What is its funciton?

A

Dome shaped window in front of eye

Main function: refraction –> covers 2/3 of focusing ability of eye

–> clear window to look through + physical and infectious barrier

Low water content

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11
Q

What is the structure and functio of the sclera?

A

It is the thogh, white connective tissue of the eye

Has a high water content

Main function: protection

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12
Q

What is the structure of the cornea?

A
  1. Epithelium
  2. Basement membrane Bowman’s Membrane
  3. Stroma –> regularity contributes towards transparency (non-vascular, supplied by corneal nerves)
  4. Basement membrane Descemet’s Membrane
  5. Endothelium –> pumps fluid out of cornea –> prevention of corneal edema –> (Cataract )
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13
Q

What happens if you hydrate the cornea?

A

It turns white

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14
Q

What is the Uvea?

A

Vascular part of eye that has three parts

  • Iris
  • Ciliary body
  • Choroid
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15
Q

How do you call the vascular layer of the eye?

What does it contain?

A

Uvea has three parts:

  1. Iris
  2. Ciliary body
  3. Choroid
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16
Q

What is the funcition of the iris?

A

It controls size of pupil and hence amount of light in the eye

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17
Q

What is the choroid?

A

Part of the Uvea

  • between sclera and retina
  • supplies back of the eye
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18
Q

Explain the structure of the lens

A

Outer Capsule (acellular)

Regular inner elongated cell fibres – transparency

–> May loose transparency with age – Cataract

19
Q

What is the function of the lens

A

it is transparent

1/3 of refraction of light

accomondation

20
Q

How is the shape of the lens controlled?

A

By lens zonules –> connective fibres connected to ciliary body –> allows change in shape for e.g. accomondation

21
Q

What is the optic disc?

A

the visible part of the optic nerve on the retina

22
Q

What is the macula?

What is its funciton?

A
  • located in the centre of the retina, temporal to the optic nerve
  • part of the retina responsible for detailed central vision.
  • Fovea= centre of macula
23
Q

What is the fovea?

A

the centre part of the macula

24
Q

What is the difference between the anterior and posteiror segment and the anterior and posteior chamber of the eye?

A

Anterior segment: Everything anterior to the lens

(posterior segment=everything posterior to lens

Anterior chamber : specific chamber between the lens and the posterior part of the cornea

Posterior chamber= Part of eye btween iris and lens (site of ciliary body)

25
Q

Explain the production, route and drainige of the aqueous humor in the eye

A

Produced by the ciliary body in posterior chamber of eye –> goes into anterior chamber of eye

Drains into Trabercular meshword

  • 90% into canal of schlemm
  • 10% into via Uveal-scleral outflow
26
Q

What is the funciton of the aqueous humour of the eye?

A

Mainly: It supplies nutrients to the cornea

Is also important in maintaining intra-occular pressure

27
Q

Explain the role of intra-occular pressure and the role of the aqueous humor in maintaining it

A

It increased aqueous humour production of decreased absorbtion–> might be an increase in intra-occular pressure

  • Intra-occular pressure is the single modifiable risk factor for glaucoma
  • Might cause Retinal Ganglion Cell Death and Enlarged Optic Disc Cupping –> blindness
28
Q

What is glaucoma?

A

Optic neuropathy with characteristic structural damage to the optic nerve, associated with progressive retinal ganglion cell death, loss of nerve fibres and visual field loss

29
Q

What is the blind spot?

A

it is the spot on the retina where the optinc nerve meets the retina –> no visual fibres –> no vision

30
Q

Explain the structural organisation of the retina

A
  1. Photoreceptors (cone+ rod cells) most posteriorly (because light is reflected at back of eye)
  2. Bipolar cells
    • Local Signal Processing to improve contrast sensitivity, regulate sensitivity
  3. Ganglion cells
31
Q

Explain the structure and the function of the fovea

A

Fovea forms the pit at the centre of the macula due to absence of the overlying ganglion cell layer

–> Fovea has the highest concentration of photoreceptors for fine vision

32
Q

What is the function and characteristic of a rod cell?

A
  • Longer outer segment with photo-sensitive pigment
  • 100 times more sensitive to light than cones
  • Slow response to light
  • Responsible for night vision
  • (Scotopic Vision)
  • 120 million rods

–> Mainly located in lateral part of vision (mostly 20-40°)

33
Q

What is the function, location and characteristics of the cone photoreceptors?

A

Less sensitive to light, but faster response

Responsible for day light fine vision and colour vision (Photopic Vision)

6 million cones

  • mainly locared at centre of vision
34
Q

What is deuteranomalie?

What is the cause for it?

A

bedingte Farbfehlsichtigkeit, bei der die Zapfenfür das Wahrnehmen von Grün das Opsin für Rot enthalten. Menschen mit Deuteranopie haben daher nur zwei statt drei verschiedene Zapfentypen.

35
Q

How many different types of cones do we have?

what is their respective function?

A

Detect light at different frequencies:

36
Q

Explain the concept of refraction

A

Light that enters a different medium that has differnt properdies gets refracted meaning

angle of incidence is > or < than angle of refraction

In convex lenses –> Light meets at one focal point

37
Q

What is the importance of the focal point in vision?

A

If the focal point meets the retina –> we see a sharp picture

If it is before (Myopia) or behind the retina (hyperopia) the picture will be blurry

38
Q

What is Emmetropia

A

focal point and distance on retina should be the same –> produces a sharp image

–> clear vision

39
Q

What is Ametropia

A

Focal point does not reach retina –> blurred vision

  1. Nearsightedness (Myopia)
  2. Farsightedness (Hyperopia)
  3. Astigmatism (Hornhautverkrümminug)
  4. Presbyopia (Altersweitsichtigkeit)
40
Q

What is Myopia?

What are possible causes for this?

A

Nearsightedness (Myopia)
focal point before retina due to

  • excessive long globe (axialmyopia) (more common)
  • excessive refractive power (refractivemyopia)
41
Q

What is Hyperopia?

What are possible causes for this?

A

Farsightedness (Hyperopia)

  • focal point not yet met when light reaches the retina
  • excessive short globe (axialhyperopia):morecommon
  • insufficient refractive power (refractivehyperopia)
42
Q

What is Astigmatism?

A

Astigmatism (Hornhautverkrümminug)

refractory medial is not spherical–> two focal points on retina emerge

43
Q

What is Presbyopia

A

Presbyopia (Altersweitsichtigkeit)

  • Naturally occurring loss of accommodation
44
Q

Explain the process of Accomondation

A
  • Contraction of the Circular Ciliary Muscle inside the Ciliary Body
  • This relaxes the zonules that are normally stretched between the ciliary body attachment and the lens capsule attachment
  • –> the lens returns to its natural convex shape due to its innate elasticity
  • This increases the refractive power of the lens

Mediated by the efferent Third Cranial Nerve

Year 2 LCRS Neurology (20 decks)

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