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Ophthalmology > 2. Ocular anatomy, history and exam > Flashcards

2. Ocular anatomy, history and exam Flashcards

1
Q

What is the function of the eyelids?

A

Protect and lubricate the eyes.

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2
Q

Secretes oily layers/tear film which prevents tears from evaporating?

A

Meibomian glands

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3
Q

Two conditions in which can cause the meibomian gland to become blocked/inflammed?

A

Stye/Chalazion

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4
Q

Name the extraocular muscles and describe the movements brought about by each?

A

medial rectus (MR)—
moves the eye inward, toward the nose (adduction)
lateral rectus (LR)—
moves the eye outward, away from the nose (abduction)
superior rectus (SR)—
primarily moves the eye upward (elevation)
secondarily rotates the top of the eye toward the nose (intorsion)
tertiarily moves the eye inward (adduction)
inferior rectus (IR)—
primarily moves the eye downward (depression)
secondarily rotates the top of the eye away from the nose (extorsion)
tertiarily moves the eye inward (adduction)
superior oblique (SO)—
primarily rotates the top of the eye toward the nose (intorsion)
secondarily moves the eye downward (depression)
tertiarily moves the eye outward (abduction)
inferior oblique (IO)—
primarily rotates the top of the eye away from the nose (extorsion)
secondarily moves the eye upward (elevation)
tertiarily moves the eye outward (abduction)

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5
Q

What muscle controls the closing of the eyelids? What facial nerve innervates this muscle?

A

Orbicularis Oculi (CNVII)

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6
Q

What muscles controls the opening of the eyelids? What nerve innervates them?

A 
Levator Palpebrae (CNIII)
Mullers Muscle (Sympathetic Tone)
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7
Q

What happens to the eyelids during Bell’s palsy and why?

A

Bells Palsy = CNVII palsy = Can’t control orbiculares Oculi = Can’t close = EXPOSURE KERATOPATHY

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8
Q

What happens to the eyelids during palsy of the CNIII?

A

CNVIII palsy = Can’t control levator palpebrae = Eyes remain shut (Ptosis . If only one muscle is affected = partial ptosis).

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9
Q

What happens to the eyelid during Horner’s Syndrome?

A

Horners = Failure of Sympathetic Nervous System = Muller’s muscle failure = Partial Ptosis

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10
Q

What gland produces tears?

A

Lacrimal Gland

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11
Q

Describe drainage route of tears.

A

Drain into lacrimal puncti, then into lacrimal sac and down nasolacrimal duct to enter nose at inferior turbinate (into inferior meatus)

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12
Q

Name the structures of the anterior segment of the eye

A 
Conjunctiva
Cornea
Iris
Ciliary Body
Aqueous Humour
Lens
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13
Q

What is the refractive power of the eye?

A

Approx 60D

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14
Q

What is the conjunctiva?

A

Mucous membrane covering the front of the eye.

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15
Q

What is the refractive power of the cornea? Describe its vasculature?

A

Approx 40D

The cornea is avascular and transparent.

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16
Q

Which structure produces aqueous humour?

A

Ciliary Bodies

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17
Q

The control of the lens shape by the ciliary muscles is known as what?

A

Accomadation

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18
Q

Which fibrous structures connects the ciliary muscle to the lens?

A

Zonules

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19
Q

If the cornea and lens are both avascular then how do they receive nutrition?

A

Through the Aqueous Humour

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20
Q

Describe the structure and relations of the lens? What is the refractive power of the lens?

A

Contained in an elastic capsule the corneal capsule.
Avascular
Suspended on Zonules, attached to Ciliary muscles
20D refractive power

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21
Q

Name the 3 layers of the cornea?

A 
Corneal Epithelium
Bowmans Layer
Stroma 
Descemet's Membrane
Corneal Endothelium
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22
Q

Which structure produces corneal epithelium?

A

Corneal epithelium – easily abraded and easily heals (24-48hrs) (from stem cells at the limbus)

23
Q

Describe the structure of corneal endothelium?

A

Only one cell layer thick
Does NOT regenerate.
Works as pump to keep cornea relatively dehydrated and clear.
If pump fails (hydration occurs)à get corneal oedema.

24
Q

What condition occurs as a result of a failure of the corneal endothelium?

A

Corneal Oedema

25
Q

Name the structures of the posterior segment of the eye?

A 
Vitreous gel
Sclera
Choroid
Retina 
Optic nerve
26
Q

What are the contents of the vitreous chamber

A

Vitreous humour, collagen fibres

27
Q

Describe the sclera of the eye?

A

Sclera – tough fibrous outer coating of eye

28
Q

Which structure is responsible for the red appearance of the eye on ophthalmoscopy and what is its function?

A

Choroid – Provides nutrition to the retina.

Red because highly vascular.

29
Q

What is the uveal tract?

A

The uvea is the vascular middle layer of the eye. It is traditionally divided into three areas

30
Q

Which structures make up the uveal tract?

A
  1. Iris
  2. Ciliary body
  3. Choroid
31
Q

Inflammation of the uvea? Types?

A

Uveitis (Ant/Posterior)

32
Q

What three structures make up the retina?

A
  1. Photoreceptors (rods and cones),
  2. Nerves (ganglion cells)
  3. Supporting cells
33
Q

Responsible for central vision (colour vision – contains lots of cone photoreceptors)

A

Macula

34
Q

Very centre of macula (specialized, contains only cones)

A

Fovea

35
Q

Which structures carry the signals from photoreceptors to the optic nerve?

A

Axons of Ganglion Cells

36
Q

Describe the blood supply of the retina?

A

Inner 2/3 from central retinal artery

Outer 1/3 from choroidal blood vessels

37
Q

Responsible for sensing contrast, brightness, and motion

A

Rods

38
Q

Responsible for fine resolution, spatial resolution, and colour vision

A

Cones

39
Q

Which are more numerous rods or cones?

A

Rods (115m v 6.5m cones)

40
Q

List the elements of the Hx to be recorded during the eye exam?

A
  • Presenting / ocular complaint? (Time of onset? Eye affected? Any associated symptoms?)
  • Past ocular history (e.g. amblyopia (lazy eye), retinal detachment?)
  • Past medical history
  • Medications history
  • Family history
  • Allergies
41
Q

What details regarding the ocular complaint should be obtained?

A

Time of onset?
Eye affected?
Any associated symptoms?

42
Q

What is visual acuity?

A

Acuity is a measure of the clarity or sharpness of vision; always test it care- fully as any loss may be serious.

43
Q

How is visual acuity tested in adults? Describe the procedure?

A

Snellen Chart

Examine the right eye first. Sit the patient 6 metres from the Snellen chart (p415); to get 6 metres in a 4-metre room, place the chart just above the patient, pointing towards a mirror 3 metres away. Obscure the left eye with a lollipop-shaped eye paddle or card, not pressed to the eye, but just enough to occlude the visual axis (more reliable than peepable through fingers or a slipping palm). Ask the patient to read the chart from the top using the right eye, then the left.

If the patient sees less than 6/6 with or without glasses, examine again with a pinhole in front of the eye: a narrow beam removes the need for focus. In simple refractive errors, acuity will improve through the pinhole. This is an important test as it shows that refractive errors are the likely cause of reduced acuity.

Each line represents what should be capable of being read at specific distances i.e. 60, 36 and 24 meters

Acuity is recorded as 6/60, 6/36, 6/24, 6/18, 6/12, 6/9, 6/6 to indicate the last line accurately read (6/6 vision is normal)

44
Q

What should be checked if a patient can’t read the top line of a Snellen Chart?

A 
If can’t read top letter…
•	CF – count fingers?
•	HM – hand movements?
•	PL – perception of light?
•	NPL – no perception of light?
45
Q

How is visual acuity tested in children?

A

Kay Picture Cards

46
Q

Pinhole Visual Acuity Testing is used, why?

A

Narrows light to only a narrow beam passing through centre of cornea/lens, removes the needed for focusing.
Can improve vision in…
1. Refractive errors
2. Mild-moderate cataract (especially peripheral cataract)

47
Q

What is the purpose of the slit lamp examination?

A

Used in conjunction with a biomicroscope. The lamp facilitates an examination of the anterior segment and posterior segment of the human eye, which includes the eyelid, sclera, conjunctiva, iris, natural crystalline lens, and cornea.

48
Q

What trick helps in remembering the cranial nerves involved in each of the eye movements?

A

LR6SO4
Lateral Rectus = 6th cranial nerve
Superior Oblique = 4th cranial nerve
Everything Else = 3rd cranial nerve

49
Q

Which muscle intorts the eye?

A

Superior Oblique

50
Q

Which muscle extorts the eye?

A

Inferior Oblique

51
Q

What should be checked for in the pupils?

A

Direct and consensual reflexes
Relative afferent pupillary defect (RAPD) (Seen on torchlight test)
(Abnormality in; CN III palsy, Horner’s syndrome, Acute glaucoma, Optic nerve disease, raised ICP)

52
Q

List the specialised visual tests studied?

A

Visual Fields Testing/Perimetry (Goldmanns Perimetry and Humphreys Perimetry)
Optical Coherence Tomography
Fundus Fluorescein Angiography

53
Q

What is begin looked for in confrontation visual fields testing?

A

Mostly looking for a neurological defect eg homonymous hemianopia

Ophthalmology (10 decks)

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