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Thought, Sense and Movement > Eyes > Flashcards

Flashcards in Eyes Deck (21)
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1
Q

What is the DVLA requirements for minimal eyesight?

A

Acuity - 6//10

Visual field - <20 degrees

2
Q

What is inflammation of the cornea called?

A

Keratis

3
Q

What three substances form tears and what secretes them?

A

Mucus - conjunctival goblet cells
Water - Lacrimal gland
Lipids - Meibomian gland

4
Q

Describe how aqueous humour drains from the eyes?

A

Leaves the anterior chamber and travels through the trabecular mesh-work and leaves via the canals of schlem

5
Q

What is normal intra-ocular eye pressure?

A

15.5 mmHg

6
Q

What do rod and cone cells synapse onto?

A

Rod - On bi-polar cell

Cone - On and Off bi-polar cell

7
Q

Describe phototransduction?

A

Photons hit the photoreceptor cells and hyper-polarise them. G-protein rector activation (Opsin which is Vit A bound) isomerises leading to Transducin enzyme activating the enzyme phospodiesterase, this hydrolyses cGMP and lowers its level which in turn blocks sodium channels

8
Q

On the lateral geniculate nucleus describe how macula and peripheral fibres synapse?

A

Macula fibres - Medial

Peripheral fibres - Lateral

9
Q

Describe the optic radiations?

A

Upper retinal fibres travel directly posterior

Lower retinal fibres travel temporally (Meyer’s loop)

10
Q

Define low vision?

A

3//60

Visual field loss of <20 degrees

11
Q

Define blindness?

A

<10 degrees

12
Q

A lesion of the macula will cause what field defect?

A

Unilateral central scatoma with distortion

13
Q

Acute optic nerve lesion will cause what field defect?

A

Unilateral central scatoma

14
Q

In the pupillary light reflex, where does the optic tract synapse?

A

Pre-tectal nucleus (bypassing the lateral geniculate)

Fibres are then sent to the Edinger/Westphall

15
Q

Describe the relative afferent pupillary defect?

A

Shine a light in affected eye = No constriction in either pupil, shine light in normal eye and both pupils will constrict (consensual and direct response), shine light in affected eye again and both eyes dilate

16
Q

What is RAPD indicative of?

A
Optic nerve (CN II damage)
Retinal detachment
17
Q

Describe the pupils of patients with afferent defects against those with efferent defects at rest?

A

Afferent problems - both pupils same size at rest

Efferent problems - both pupils different size at rest

18
Q

Describe what can efferent defects?

A

Failure to constrict - CN (III) palsy/acute glaucoma

Failure to dilate - Horner’s syndrome/ Uvitis

19
Q

Describe medical conditions that may bring about painful sudden loss of vision?

A

Acute (open-angled) glaucoma

Optic nerve neuritis

20
Q

Describe medical conditions that may bring about painless sudden loss of vision?

A

Retinal detachment
Macular degeneration WET
Vitreous haemorrhage

21
Q

Describe medical conditions that may bring about a gradual loss of vision?

A

Cataracts
Chronic glaucoma
Optic nerve and pathway tumours
Macular degeneration DRY