Opthalmology Anatomy Flashcards

1
Q

Describe the opthalmoscope view of the retina in terms of temporal and nasal

A

Temporal - Macula and Fovea

Nasal - Optic disc and vessels

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2
Q

Name three roles of the eyelid

A

Protect cornea and eyeball from injury

Keep cornea moist

Contain glands

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3
Q

What are the three main glands of the eyelid?

A

Meibonium - secretes lipid into tear film

Glands of Moll - Modified sebaceous glands

Glands of Zeiss - Sebaceous Glands

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4
Q

Describe the lacrimal pathway

A
  • Tears drain from lacrimal gland into excretory lacrimal ducts
  • From the ducts the tears drain into lacrimal lake
  • Lacrimal canaliculi into lacrimal sac
  • Nasolacrimal duct into inferior meatus
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5
Q

Describe the innervation of the lacrimal gland

A

Somatic supply from lacrimal nerve (branch of Opthalmic)

Parasympathetic increases production
Sympathetic decreases production

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6
Q

Why does Epiphora occur? Why is this a danger?

A

There isn’t an anastomotic pathway in the lacrimal system
Obstruction will give rise to overflow of tears

Stagnant tears can predispose to infection

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7
Q

The tear film is regenerated every time blinking occurs. Give three roles

A

-Anti bacterial
-Lubrication
- Creates smooth ocular surface for light to be refracted unifrp,
Y

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8
Q

What are the three components of the tear film?

A
  • Surface Lipid- Meibomian secretion
  • Middle Aqueous - Lacrimal and Accessory Lacrimal secretion
  • Inner Mucous - Goblet cells of conjunctiva/epithelial surface
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9
Q

What is the outer protective layer of the eyeball?

A

Sclera and Cornea

Fibrous attachment for extraocular muscles

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10
Q

What is the middle layer of the eyeball?

A

Choroid, Ciliary Body and Iris

Rich vasculature

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11
Q

What is the inner layer of the eyeball?

A

Retina (optic and non visual parts)

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12
Q

What is the Iris?

A

Thin contractile diaphragm

Central pupil to allow light through

Size controlled by sphincter (parasympathetic) and dilator (sympathetic) papillae muscles

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13
Q

What is the Lens?

A

Transparent biconvex structure enclosed in a capsule
Attached to ciliary body by suspensory ligaments
Size of lens changed by ciliary contraction

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14
Q

What are the two layers of the retina?

A
Neural Layer (light receptive) 
Pigmented Layer
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15
Q

What is the optic disc?

A

Depression on the fundus of the eye

Where optic nerve leaves the eye

Contains nerve fibres and NO photoreceptors (blind spot)

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16
Q

Lateral to the optic disc is the macula and fovea. What are these?

A

Macula - photoreceptors cells specialised for visual acuity

Fovea - centre of macula (highest visual acuity)

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17
Q

What muscle opens the eye?

A

Levator Palpebrae Superioris

Inserts into skin and tarsal plate
Inner gated by oculomotor

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18
Q

What are the four recti muscles of the eye?

A

Superior, Inferior, Medial, Lateral

All arise from common tendinous ring around optic nerve and insert on sclera

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19
Q

What are the two oblique muscles of the eye?

A

Superior and inferior

Work synergistically with recti

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20
Q

What is the role of the optic nerve?

A

Transmit all visual information
Light reflex
Accommodation reflex

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21
Q

What are the subdivisions of the Opthalmic Nerve (from trigeminal)?

A

Lacrimal
Frontal
Nasociliary
Ciliary

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22
Q

What does the Lacrimal Nerve innervate?

A

Supplies Lacrimal gland

Sensory to lacrimal gland, upper outer conjunctiva, lateral eyelid and lateral forehead

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23
Q

What does the frontal nerve innervate?

A

Skin of forehead
Upper eyelids
Mucosa of frontal sinus

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24
Q

What does the Ciliary branch of the Opthalmic nerve innervate?

A

Sensory innervation of eyeball

Dilator pupillae

25
Describe the arterial supply of the eye
Mainly from the Opthalmic artery Retina is supplied by the central retinal artery branch
26
Describe the venous drainage of the Eye
Opthalmic veins that drain into cavernous sinus
27
What is the cornea?
A transparent layer of the eye that separates the tear film and the anterior chamber
28
Give three roles of the Cornea
Maintaining transparency Protecting the eye (eg corneal reflex) Refraction of incoming light
29
What are the five sub layers of the cornea
``` Epithelium Bowmans Stroma Descemets Membrane Endothelium ```
30
How is the corneal epithelium repaired when damaged?
Cells migrate from basal layer to replace, and from periphery to centre Cells on the surface spread out to cover defect before basal cell layer replaces Regenerates within 14 days (longer if central as stem cells are peripheral)
31
What is the Bowmans layer of the cornea?
Acellular layer Trauma below this layer - corneal scarring
32
What is the Endothelium of the cornea?
Maintains hydration of cornea so it is transparent Doesn’t regenerate - loss is replaced by change in size/shape
33
Describe the pathway of humour drainage
Produced by ciliary processes of ciliary body Flows between iris and anterior surface of lens through the pupil Flows through iridocorneal angle (trabecular meshwork and canal of schlemm) Through episcleral vessels and into systemic venous circulation
34
What is the unconventional drainage of aqueous humour?
Into root of iris before draining into Scleral vascular system
35
How is Intraocular Pressure Measured?
Measured by the force needed to flatten the corneal surface using a tonometer The greater the force required, the higher the pressure
36
What is the normal range of intraocular pressure?
11-21 mmHg Note: Correlation factor of corneal thickness
37
Describe the autonomic control of IOP
Alpha 2 Adrenoreceptors - reduce IOP by reducing production and increasing flow Beta 2 Adrenoreceptors - increase IOP by increasing production and reducing flow
38
Name 6 classes of drugs targeting Aqueous Humour
``` Beta Blockers (Timolol) Alpha Agonists (Brimonidine) PG Anologues (Latanoprost) Carbonic Anhydrase Inhibitors (Dorzolamide) Parasympathomimetic (Pilcarpine) ```
39
How does Timolol work?
Reduces humour production
40
How do Alpha Agonists work?
Reduces production and increase drainage
41
How does Latanoprost work?
Increases uveoscleral flow
42
How does Dorzolamide work?
Reduces aqueous humour production
43
What are the roles of the Lens?
Refract light (less powerfully than cornea) Changing refraction by accommodation (capsule changes shape)
44
Describe the composition of the Lens Epithelium
Undergoes mitosis throughout whole life Newest lens (softest in the outside) Fibres tightly packed and organised to maintain transparency
45
Name three roles of the ciliary body
Accommodation Aqueous humour production Attachment for lens zonules
46
Name four roles of the Choroid
- Allows nerves and vessels to anterior eye - Removes waste products to outer retina - Supplies nutrients to outer retina - Absorbs any light passing through retina to prevent reflection and obscured vision
47
What is affected in Anterior Uveitis?
Iris and/or ciliary body
48
What is affected in Intermediate Uveitis?
Posterior part of ciliary body and nearby peripheral choroid and retina
49
What is affected in Posterior Uveitis?
Inflammation of retina and choroid
50
What is the Vitreous?
Cavity filled with aqueous humour Attached to the posterior lens capsule and retina at several points Holds retina in place and supports lens
51
What is the relevance of cataract surgery and the vitreous?
Cataract surgery can cause disruption of the posterior lens capsule and vitreous membrane allowing humour flow into anterior chamber
52
What happens to the vitreous as you age?
Fluid fills in potential space between vitreous and retina Can detach where it is weakly bound Vitreous detachment can predispose to retinal detachment
53
What is the role of the neural retina?
Converts light stimulus to nervous impulses Travels along ganglion cells in axons to be processed in visual cortex
54
What are Rods?
Photoreceptors that sense contrast and motion, and assist in dark environments Not good for detail (B&W)
55
What are Cones?
Used for fine detail and colour vision
56
The Retina is a metabolically active tissue so requires a good blood supply. Describe this
Outer 1/3 - Choroidal Inner 2/3 - Central Retinal Artery (giving off four end arteries) Macula has a dense capillary network Fovea is capillary free (reliant on underlying choreocapillaris)
57
Describe the pupillary light reflex
Afferent fibres leave visual pathway and synapse on pretectal nucleus Fibres travel to both EWN nuclei Efferent fibres leave EWN and synapse on ciliary ganglion (activating sphincter pupillae)
58
What bones make up the walls of the orbital cavity?
Roof - Frontal Bone Lateral - Zygomatic bone Posterior - Greater wing of Sphenoid Inferior - Maxilla
59
Tears are composed of water, protein, salts, lipids and mucins . Give four roles
Hydration Immunology Nourishment Lubrication