Week 130 - Sudden Visual Disturbance (Provisional) Flashcards
What does LogMAR stand for?
Logarithm of Minimal Angle of Resolution
What can cause retinal neuropathy?
- Compression
- Infection
- Ischaemia
- Inflammatory
- Congenital
- Hereditary
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.
What do tears contain that help to provide an antimicrobial function?
- Lactoferrin
- Lysozome
- Beta-lysin
- IgA, IgG
- Complement
- Leukocytes
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)
What is the required visual acuity for driving in the UK?
6/12
Week 130 - Sudden Visual Disturbance: At which point does a patient become visually impaired? (In terms of acuity)
6/36
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.
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.
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.
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.
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.
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.
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.
Week 130 - Sudden Visual Disturbance: What is the name of the tendinous ring that the four rectus muscles form?
Annulus of Zinn
Week 130 - Sudden Visual Disturbance: Which structures pass through the annulus of Zinn?
- Optic Nerve
- Opthalmic artery
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.
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)
