Intraocular Anatomy Flashcards

1
Q

Name the three tunics of the ocular globe

A

Nervous. Vascular, Fibrous

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1
Q

What are the three parts of the fibrous tunic

A

Cornea, Sclera, Limbus

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2
Q

Describe features of the cornea

A

Anterior 1/4 of globe Optically clear Avascular Highly innervated
Cornea

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3
Q

Describe features of the sclera

A

Posterior 3/4 of globe White dense connective tissue Opaque Vessels penetrate sclera to supply deeper tunics

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4
Q

Describe the limbus

A

Junction of the cornea and sclera Attachment site of bulbar conjunctiva

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5
Q

What is the vasculature for the fibrous tunic

A

Conjunctival vessels
scleral vessels

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6
Q

List the three components of the vascular tunic

A

Choroid (posterior part)
Ciliary body and Iris (anterior part)

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7
Q

What is another name for the vascular tunic

A

Uvea or Uveal tract

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8
Q

Describe the choroid

A

Superficial to visual retina
Pigmented
Contains tapetum lucidum
Highly vascular - vascular supply to the retina

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9
Q

Describe the ciliary body

A

Anterior to choroid
Superficial to non visual retina
Has radially oriented processes
Has ciliary process and ciliaris muscle

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10
Q

Describe the iris

A

Anterior to ciliary body
Superficial to non visual retina
Forms the pupil

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11
Q

Describe the tapetum lucidum

A

Specialized reflective layer
Increases light reaching retina
Allows for night vision
Absent in pigs and humans

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12
Q

Describe the ciliary process

A

Radially oriented extensions of the ciliary body Site of attachment of zonule fibers

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13
Q

Describe the ciliaris muscle

A

Muscle deep within ciliary body

Contraction draws ciliary body centrally

Lowers tension on zonule fibers - causes lens to become convex (look at nerby objects)

Parasympathetic innervation- CN III

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14
Q

Describe the iris

A

Forms the pupil
The pupil controls the amount of light that reaches the retina
Choroid
iris muscles controls pupil size: iris dilator and constrictor

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15
Q

Describe the iris dilator m

A

Radial muscle fibers Contraction increases pupil size “Mydriasis”- large pupil size Sympathetic innervation

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16
Q

Describe the iris contrictor m

A

Circular muscle
Contraction decreases pupil size
“Miosis”- small pupil size
Parasympathetic innervation- CNIII

17
Q

What are the boundaries of the anterior chamber

A

From the cornea to the iris

18
Q

What are the boundaries of the posterior chamber

A

Iris to lens

19
Q

What structure holds the anterior chamber open so as not to disrupt flow of aqueous humor

A

Pectinate lig

20
Q

Describe the arrangement of the iris contrictor muscle fibers in the cat

A

Sine wave

21
Q

What are iridic granules

A

Normal vascular structures on superior aspect or iris margin of horses and bovine

Purpose to to absorb extra light/protect

Note: on both superior and inferior for camelids

22
Q

What is another name for the nervous tunic and what are the three components of it

A

The retina

Pars optica retinae, pars ciliaris retinae, pars iridica retinae

23
Q

Describe the pars optica retinae

A

Lines deep aspect of the choroid
The ‘Visual Retina’
Contains light sensing cell layers

24
Q

Describe the pars ciliaris retinae

A

Lines deep aspect of the ciliary body - ciliary epithelium
Part of the ‘Non-visual Retina’
No light sensing cell layers
Produces aqueous humor

25
Q

Describe the pars iridica retinae

A

Lines posterior aspect of the iris
Part of the ‘Non-visual Retina’

26
Q

What are the two basic layers of the nervous tunic

A

Pigmented retinal epithelium (PRE)
Nervous layer

27
Q

describe the pigmented retinal epithelium

A

Present in pars optica retina, pars ciliaris retina, pars iridica retina

Adjacent to choroid, ciliary body, and iris

UNPIGMENTED where it lines tapetum lucidum! - allows light to reach “mirror like”

28
Q

Describe the nervous layer

A

Layers of neuronal cells and photoreceptors

Present in pars optica retina only- the visual retina

Deep to the pigmented retinal epithelium (PRE)

light receptor layer is thick over choroid and then dramatically thins anteriorly

29
Q

Describe which structures the optic cup develops into embyrologically

A

Outer layer of optic cup –> Pigmented layer of the retina (1 layer)

Inner layer of optic cup –> Neural layer (layers 2-10)

30
Q

Where does detachment of the retina occur?

A

Between pigmented layer (PRE) and nervous layer (layers 2-10)

31
Q

What is the ora serrata

A

junction where retina becomes thinner and visual/nonvisual retina connect

the serrated junction between the retina and the ciliary body. This junction marks the transition from the simple non-photosensitive area of the retina to the complex, multi-layered photosensitive region.

32
Q

describe the lens

A

Located posterior to iris and pupil
Biconvex with an elastic capsule
Suspended by zonule fibers
Optically clear
Refracts light

33
Q

What are lens fibers

A

Arranged concentrically in layers
Extend from anterior pole to posterior pole Join at poles in Y shape- “Y Sutures”

34
Q

What is accomodation and how does it occur

A

Change in lens shape for visual focus

distance vision - Sympathetic stimulation, Ciliary m relaxed

near vision - Parasympathetic stimulation, Ciliary m contracted

35
Q

What are the boundaries of the vitreous chamber and what is inside

A

lens and the retina

filled by vitreous body

36
Q

What are the two segments of the ocular globe and what defines their boundaries

A

Anterior Segment: All the parts of the globe from the cornea to the lens

Posterior Segment: All the parts of the globe posterior to the lens

37
Q

What is aqueous humor and what are its characteristics

A

Fluid present in the anterior and posterior chambers

A clear colorless fluid similar to CSF

Low protein content

Functions to maintain intraocular pressure and nourish cornea and lens

Aqueous humor production is constant - therefore to maintain intraocular pressure drainage must be constant

38
Q

Describe the flow of aqueous humor

A

Produced by the pars ciliaris retina (“ciliary body epithelium”)

Flows into posterior chamber

Flows through pupil into anterior chamber

Drains at iridocorneal angle through a meshwork formed by the pectinate ligaments

Fluid is absorbed into the scleral venous sinuses and plexus

39
Q

Describe the vitreous body and clin sig

A

Gel-like mass Maintains shape of globe Holds retina against choroid Constant in volume

if lost can lead to retinal detachment, why lens capsule (which is connected to the VB) is left if surgery is performed the remove the lens

40
Q

What is the fundus and what structures are present in it

A

The posterior globe as seen through an ophthalmoscope

Structures of the Fundus:
Optic disc Visual retina Retinal vessels Tapetum lucidum