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Ocular Phys Block 10 > Function Of The Ciliary Body > Flashcards

Function Of The Ciliary Body Flashcards

1
Q

What is not a function of the ciliary body

A

Contains the minor arterial circle of the iris

-does contain the major circle

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2
Q

Order the structures appear on gonioscopy

A

Schwalbes line
TM
Sclera spur
Ciliary body

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3
Q

Are both posterior structures from the iris and the ciliary body pigmented?

A

No, iris is pigemented on the backside and the ciliary body is nonpigmented on the backside

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4
Q

Connected the cornea to the conjunctiva

A

Schwalbes line

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5
Q

Why is the ciliary muscle atypical for smooth muscle

A

Rapid contraction speed
Large size of motor neurons
Distance between the muscle and the motor neurons
Structure of the ciliary muscle cells resembles skeletal muscle

This is because we are constantly changing accommodation

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6
Q

Ciliary muscle in birds

A

It is skeletal muscle

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7
Q

Functions of the ciliary body

A
  • aqueous production
  • aqueous outflow
  • accommodation
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8
Q

What is aqueous production important for

A

Supplies nutrients to lens and cornea BC they are avascular

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9
Q

What is aqueous outflow important for

A

Maintain IOP

Remove waste products

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10
Q

Production and secretion of aqueous humor

A
  1. Diffusion
  2. Ultrafiltration
  3. Active secretion (80-90% of production)
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11
Q

What is the most significant factor in aqueous production

A

Active secretion

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12
Q

What is the purpose of aqueous production

A
  • nutrients to cornea and lens
  • ascorbate cxn 20x higher in aqueous than in blood plasma
  • free radical that is important to prevent oxidative damage
  • low cxn of protein to prevent light scatter
  • carries waste products from cornea and lens
  • high cxn of lactate in aqueous, metabolic waste product of glycolysis of the lens and cornea
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13
Q

Ascorbate in aqueous

A

20x higher than in the blood

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14
Q

What is ascorbate in the aqueous important for

A

Prevent oxidative damage

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15
Q

Protein in the aqueous

A

Low levels to prevent light scatter

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16
Q

Lactate in the aqueous

A

High cxn of lactate which is a metabolic waste produce of glycolysis of the lens and cornea

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17
Q

How much aqueous is produced per minute

A

2.5 microliter

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18
Q

When is aqueous production higher

A

During the day, decreases 50% at night

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19
Q

Blood vessels and aqueous

A

Dilating and constricting blood vessels can influence aqueous blood vessels by increasing and decrease blood volume

Heh?

20
Q

Size of zonular fibers

A

70-80nm in diamter

21
Q

What are the zonular fibers

A

Elastic fibers
Stabilize the lens
Allows fluid to flow from posterior chamber to the vitreous chamber
Superficial attachment to the lens

22
Q

When is acocmmodation completely lost by

A

Age 50

-some presbyopia read well due to pupil constriction and miosis

23
Q

Tell me about accommodation

A

Contraction of the longitudinal fibers of the ciliary muscel pulls the choroid forward, the contraction of the circular fibers draws the ciliary body closer to the lens,decreased the diameter of the ring formed by the ciliary body. This releases tension on the zonular fibers and allows the lens capsule to adopt a more spherical shape. The lens thickens, and the anterior surface curvature increases. These changes result in an increase in refractivepower or accommodation

24
Q

What is the lens contained in

A

An elastic envelope, the lens capsule

25
Q

What is the lens capsule suspended by

A

Zonular fibers that arise from the dilatory epithelium and attach to the lens equator

26
Q

Zonular fibers in far vision

A

While far vision is maintained the ciliary muscle is relaxed. Zonular fibers are pulling on the lens capsule

27
Q

What happens to the zonular fibers when the ciliary muscle contracts?

A

The fibers slacken. The lens adopts a new shape with the anterior surface building forward and the lens becoming thicker with a decreased diamter thereby increasing the power of the lens

28
Q

What does ACh bind

A

Ciliary muscle receptors (M)

29
Q

Pilocarpine and ciliary muscle

A

Binds M receptors and can cause contraction

30
Q

Which eyes will be less effected by dilating drops

A

Pigmented epithelium in the iris and ciliary body bind with this. Dark irides will therefore be less effected by dilating drops

31
Q

Ciliary muscle can be temporarily paralyzed with _____

A

M antagonists like atropine, cyclopentolate, and tropicamide

32
Q

Measuring accommodation

A
  • rely on perception of clarity
  • overestimate accommodative response
  • acocmomdation and convergence stimulate miosis
  • objective measurements can be obtained from autorefractoe and aberrometer
  • push up test has an increase in letter size
  • changes in illumination will after pupil diamter was well
33
Q

What is reduce near vision from

A

Not a loss of ciliary body muscel function but from a thickened and stiff lens

34
Q

Structural changes in aging eye that can affect accommodation

A

Thickening of tendons, reduced muscle mass and increase in connective tissue

35
Q

Muscarinic receptors and aging

A

No cchange at all

36
Q

Loss of the ability to accommodate

A

Presbyopia

-normal are-related change and the subject of significant research

37
Q

Tendons and presbyopia

A

The tendon attaches the ciliary muscle to the scleral spur shows extensive age-related structural changes: it thickens with age and becomes surrounded by a dense layer of collagen thus losing its elasticity , restricts muscle movement

38
Q

Ciliary muscel contractive power

A

Increases up until age that presbyopia manifests

  • no change in zonular length with age
  • aging ciliary muscle looks like young when relaxed
39
Q

Ciliary strength and age

A

Gets stronger as you get older

40
Q

Ciliary muscle contraction and aqueous outflow

A

Ciliary muscle contraction can change the configuration of the TM BC some of the longitudinal fibers are attached to TM sheets. This altered configuration can facilitate aqueous movement through the anterior chamber angle structures

41
Q

Accommodation and IOP

A

Reduction

42
Q

Iris sphincter muscle is derived from

A

Neural ectoderm

43
Q

Ciliary muscle is derived from

A

Mesoderm

44
Q

If breakdown of blood aqueous nbarrier occurs, cells and flare will be visible

A

Tyndall phenomenon

45
Q

Factors of Tyndall phenomenon

A
  • leukocyte
  • usually whitish
  • can form hypopyon
46
Q

Trauma to head or injury such as whiplash can tear or break the iris. This can break the iris blood vessels entering from the major circle of the iris nad blood settles inferiroly

A

Hyphema

47
Q

How to locate schwalbes line on gonio

A

Look where the two lines of light on the cornea come together and that is it

Ocular Phys Block 10 (5 decks)

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