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Thought, Sense and Movement > Eyes > Flashcards

Flashcards in Eyes Deck (21):
1

What is the DVLA requirements for minimal eyesight?

Acuity - 6//10
Visual field - <20 degrees

2

What is inflammation of the cornea called?

Keratis

3

What three substances form tears and what secretes them?

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

4

Describe how aqueous humour drains from the eyes?

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

5

What is normal intra-ocular eye pressure?

15.5 mmHg

6

What do rod and cone cells synapse onto?

Rod - On bi-polar cell
Cone - On and Off bi-polar cell

7

Describe phototransduction?

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

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

Macula fibres - Medial
Peripheral fibres - Lateral

9

Describe the optic radiations?

Upper retinal fibres travel directly posterior
Lower retinal fibres travel temporally (Meyer's loop)

10

Define low vision?

3//60
Visual field loss of <20 degrees

11

Define blindness?

<10 degrees

12

A lesion of the macula will cause what field defect?

Unilateral central scatoma with distortion

13

Acute optic nerve lesion will cause what field defect?

Unilateral central scatoma

14

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

Pre-tectal nucleus (bypassing the lateral geniculate)
Fibres are then sent to the Edinger/Westphall

15

Describe the relative afferent pupillary defect?

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

What is RAPD indicative of?

Optic nerve (CN II damage)
Retinal detachment

17

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

Afferent problems - both pupils same size at rest
Efferent problems - both pupils different size at rest

18

Describe what can efferent defects?

Failure to constrict - CN (III) palsy/acute glaucoma
Failure to dilate - Horner's syndrome/ Uvitis

19

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

Acute (open-angled) glaucoma
Optic nerve neuritis

20

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

Retinal detachment
Macular degeneration WET
Vitreous haemorrhage

21

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

Cataracts
Chronic glaucoma
Optic nerve and pathway tumours
Macular degeneration DRY