Refractive errors and visual field defects Flashcards Preview

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Flashcards in Refractive errors and visual field defects Deck (40):
1

Emmetropia

No refractive errors

2

Myopia

Short sightedness
Vision is better for near than for further away

3

Myopia - positive/negative lens

Negative lens

4

Myopia - concave/convex lens

Concave lens

5

Myopia - relationship with the retina

Visual images come in to focus in front of the retina
- images focus too early

6

Myopia - converges/diverges light?

Diverges

7

Hypermetropia

Long sightedness
Vision is better for further away than near objects

8

Hypermetropia - positive/negative lens

Positive lens

9

Hypermetropia - concave/convex lens

Convex lens

10

Hypermetropia - relationship with the retina

Visual images come into focus behind the retina
- images focus too late

11

Hypermetropia - converges/diverges light

Converges

12

Presbyopia - definition

Power loss due to age

13

Presbyopia - positive/negative lens

Positive lens

14

Presbyopia - concave/convex lens

Convex lens

15

Accomodative esotropia

Patient with hypermetropia with a manifest squint in which the eye is turned in

16

Astigmatism - definition

Eye does not focus evenly on the retina
Eye has 2 surfaces to correct
There is shape correction needed

17

Astigmatism - clinical features

Constant blurred vision at all distances

18

Diplopia

Double vision

19

Horizontal diplopia

Images are side by side
Problem with LR or MR

20

Vertical diplopia

Images are one on top of the other
Problem with SO, SR, IR, IO

21

Esotropia - definition

Inward squint, convergent squint

22

Esotropia - what movement do you see when covering good eye

Outward movement

23

Exotropia - definition

Outward squint, divergent squint

24

Exotropia - what movement do you see when covering good eye

Inward movement

25

Hypertropia - definition

High eye

26

Hypertropia - what do you see when covering good eye

Downward movement

27

Hypotropia - definition

Low eye

28

Hypotropia - what do you see when covering good eye

Upward movement

29

Visual field pathway

Optic nerve ->
Optic chiasm ->
Optic tracts ->
Optic radiations ->
Occipital cortex

30

Visual field defect

A lesion anywhere along the visual field pathway which results in a visual field defect

31

Optic nerve defect - cause

Ischaemic optic neuropathy
Optic neuritis
Tumours

32

Optic chiasm defect - cause

Pituitary tumour

33

Optic tracts and optic radiation defect - cause

Tumours
Demyelination

34

Occipital cortex - cause

Vascular disease (CVA)
Demyelination

35

Optic nerve problem - patients vision

Can't see at all in the affected eye

36

Optic chiasm problem - patients vision

Loss of temporal vision in both eyes (as temporal vision hits nasal retina and this crosses at optic chiasma)

37

Optic tract / optic radiation problem - patients vision

Visual field loss on the same side of both eyes (e.g. temporal vision lost on right eye, nasal vision lost on left eye)

38

Occipital cortex problem - patients vision

Visual field loss on the same side of both eyes (e.g. temporal vision lost on right eye, nasal vision lost on left eye) but macula is not affected

39

Sudden vision loss - causes

Vascular aetiology
- CRAO
- CRVO
Vitreous haemorrhage
Retinal detachment
Wet ARMD
Closed angle glaucoma

40

Gradual visual loss - causes

Cataract
Dry ARMD
Refractive error
Open angle glaucoma
Diabetic retinopathy