Week 130 - Sudden Visual Disturbance (Provisional) Flashcards Preview

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Flashcards in Week 130 - Sudden Visual Disturbance (Provisional) Deck (45):
1

What does LogMAR stand for?

Logarithm of Minimal Angle of Resolution

2

What can cause retinal neuropathy?

• Compression

• Infection

• Ischaemia

• Inflammatory

• Congenital

• Hereditary

3

What is Leber's hereditary optic neuropathy?

• Very rare

• Mitochondrial - So affects tissue with high energy demands.

• Sequential painless loss of vision in late teens or twenties.

4

What do tears contain that help to provide an antimicrobial function?

• Lactoferrin
• Lysozome
• Beta-lysin
• IgA, IgG
• Complement
• Leukocytes

5

Week 130 - Sudden Visual Disturbance: What is the six point examination sequence for eyes?

• Acuity

• Eye movements

• Pupils

• Visual fields

• External inspection / anterior segment

• Fundoscopy 

• (Intraocular pressure if you have access to a tonometer)

6

What is the required visual acuity for driving in the UK?

6/12

7

Week 130 - Sudden Visual Disturbance: At which point does a patient become visually impaired? (In terms of acuity)

6/36

8

Week 130 - Sudden Visual Disturbance: What is a relative afferent pupillary defect?

• Diagnosed using the swinging light test.

• When the light is shone in the good eye, there will be a consensual response in both eyes and they will constrict.

• When the light is swung to the bad eye, the pupils will continue to dilate, this is due to a relative difference in response to the light between the two eyes.

• Also known as marcus-gunn pupils.

9

Week 130 - Sudden Visual Disturbance: What is a retinablastoma and how can it be detected with an opthalmoscope?

• Eye cancer that affects children under the age of 5.

• The absence or asymetry of a red reflex can indicate a retinoblastoma.

10

Week 130 - Sudden Visual Disturbance: A teenage boy presents to clinic with a history of worsening visual loss. On examination there is poor visual acuity, pupil reactions are abnormal, normal red reflex, pale right and swollen left disc, normal neurological examination and investigations are normal. What is the likely diagnosis?

Optic Neuropathy.

11

Week 130 - Sudden Visual Disturbance: The vision from which part of each eye crosses at the optic chiasm?

The lateral parts.

Therefore if you were to have a lesion in the middle of the optic chiasm, you would lose lateral sight from both eyes.

12

Week 130 - Sudden Visual Disturbance: If a patient presented with loss of the left side of their vision from both eyes, where would the location of the lesion be?

Right optic tract.

Since the signal from the left lateral will cross at the chiasm, and the signal from the right medial will remain on the right.

13

Week 130 - Sudden Visual Disturbance: Explain the vision loss that would occur with a lession at each of the following locations; Right optic nerve, Optic Chiasm, Left optic tract. 

Right Optic Nerve - Complete visual loss of right eye.

Optic Chiasm - Loss of lateral vision of both eyes.

Left optic tract - Loss of right sided vision from both eyes.

14

Week 130 - Sudden Visual Disturbance: What will the visual loss be in the optic radiation?

• Depending on whether it is right/left and which fibre it is, you will lose a quarter of the vision. i.e. Left sided lesion you will lose a quarter on the right side of both eyes.

• If it occurs further along, then it will be a similar pattern but the centre of the vision will be spared.

15

Week 130 - Sudden Visual Disturbance: What is the name of the tendinous ring that the four rectus muscles form?

Annulus of Zinn

16

Week 130 - Sudden Visual Disturbance: Which structures pass through the annulus of Zinn?

• Optic Nerve

• Opthalmic artery

17

Week 130 - Sudden Visual Disturbance: Which muscle is responsible for the elevation and retraction of the upper eyelid? What is its innervation?

Levator Palpabrae Superioris

Sympathetic - from the ciliary ganglion

Voluntary - Superior division of the occulomotor nerve.

18

Week 130 - Sudden Visual Disturbance: What is the innervation and function of the lateral rectus?

• Abducts the eyeball away from the midline (moves laterally).

• Innervated by the abducens nerve (CNVI)

 

19

Week 130 - Sudden Visual Disturbance: What is the function and innervation of the medial rectus?

• Adducts the eyeball, medially towards the midline.

• Occulomotor nerve (CNIII)

20

Week 130 - Sudden Visual Disturbance: What is the function and innervation of the superior rectus?

• Elevates eyeball, points pupil upwards.

• Occulomotor nerve (CNIII).

21

Week 130 - Sudden Visual Disturbance: What is the function and innervation of the inferior rectus?

• Depresses the eyeball, points the pupil downwards.

• Occulomotor (CNIII)

22

Week 130 - Sudden Visual Disturbance: What is the function and innervation of the inferior oblique?

• Elevates the eyeball in abduction.

• Occulomotor nerve (CNIII)

23

Week 130 - Sudden Visual Disturbance: What is the function and innervation of the superior oblique muscle?

• Depression whilst in abduction.

• Trochlear (CNIV)

24

Week 130 - Sudden Visual Disturbance:  What is the equation for remembering the innervation of the extraocular muscles?

(LR6 SO4)3

25

Week 130 - Sudden Visual Disturbance: What are the symptoms and pathophysiology of Horner's syndrome?

• Ptosis, miosis (constriction of pupil), Anhidrosis

• Due to disruption of the sympathetic fibres to the head and the neck.

• Can be due to pancoast tumour of the lung, thoracic aortic aneurysm, Traum and compression.

26

Week 130 - Sudden Visual Disturbance:  What is the management for blunt trauma of the eye leading to hyphaema?

• Blood in anterior chamber of the eye.

• Rest, steroids, +/- mydriatic eye drops(dilators)

27

Week 130 - Sudden Visual Disturbance:  What is the management in perforating trauma of the eye?

• Surgical repair

• Rest

• Antibiotics

• Steroids

• +/- mydriatic

28

Week 130 - Sudden Visual Disturbance: What are some of the corneal causes of sudden visual loss?

• Loss of clarity

• Corneal infection

• Acute pressure rise

29

Week 130 - Sudden Visual Disturbance:  What are some of the anterior chamber causes of sudden visual loss?

• Loss of clarity

• Hyphaema

• Pus

• Acute infection / inflammation

30

Week 130 - Sudden Visual Disturbance: What are some of the lens causes of sudden visual disturbance?

• Loss of clarity

• Acute Cataract

• Dislocation

31

Week 130 - Sudden Visual Disturbance: What are some of the vitreous causes of sudden visual loss?

• Blood

• Loss of clarity

• Abnormal Vessels

• Pus

32

Week 130 - Sudden Visual Disturbance: What are some of the retinal causes of sudden visual loss?

• Detachment

• Macular causes

• Vascular occlusions

33

Week 130 - Sudden Visual Disturbance: What is loss of vision associated with age called?

Age related macular degeneration.

34

Week 130 - Sudden Visual Disturbance: What are the two forms of age related macular degeneration? What is the relative abundance of each?

• Atrophic - 90%

• Exudative - 10%

35

Week 130 - Sudden Visual Disturbance: What is the presenting symptom of age-related macular degeneration?

• Distortion/loss of central vision

36

Week 130 - Sudden Visual Disturbance: What are the differences between 'wet' and 'dry' age-related macular degeneration?

• 'Wet' - neovascularisation, usually has a great effect on vision.

• 'Dry' - drusen and abnormalities of retinal pigment epithelium (RPE). Does not have too much effect vision unless significant atrophy of RPE develops.

37

Week 130 - Sudden Visual Disturbance: What medical treatment is availible for neovascularising age-related macular degeneration?

• Anti-Vegf

• Vascular endothelial growth factor.

• Reverses new vessel formation.

• But it is expensive and given via monthly injections.

38

Week 130 - Sudden Visual Disturbance: Give an example of a sympathomimetic and describe the mechanism.

• Phenylephrine

• Acts on the alpha1-receptors and causes mydriasis.

• Acts within 90minutes and last for 5-7hrs.

39

Week 130 - Sudden Visual Disturbance: Give some examples of anti-muscarinics and describe the mechanism.

• Atropine, Cyclopentolate, Tropicamide.

• Blocks ACh and muscarinic receptors.

• Causes mydriasis.

• Effective in 15 mins and last for 4-6 hours.

40

Week 130 - Sudden Visual Disturbance:  What are the symptoms for acute angle-closure glaucoma?

• Red, painful eye

• Nausea and Vomitting

• Headache

• Blurred Vision

41

Week 130 - Sudden Visual Disturbance: What drug is used in the treatment of glaucoma and what is its mechanism?

• Pilocarpine

• Parasympathomimetric

• Mimics the effect of ACh on muscarinic receptors, causing constriction of the pupil.

42

Week 130 - Sudden Visual Disturbance: Which class of drugs can be used to inhibit aqueous humor production? Give an example.

• Beta-Blockers e.g. Timolol

43

Week 130 - Sudden Visual Disturbance: Give some examples of artifical tears/lubricants. Give a brief description for each.

• Hypromellose - 1st line, supplements aqueous layer.

• Carbomers - Thixotrophic to prolong retention.

• Polyvinyl alcohol - Surfactant, good replacement for mucin layer.

• Ointments - Highly viscous, so long lasting but blur vision.

44

Week 130 - Sudden Visual Disturbance: Which medication is given in order to make the eye easier to examine for areas of damage to cornea or conjuctiva?

Fluoroscein

45