Refractive errors and visual field defects

Question 1

Emmetropia

Answer 1

No refractive errors

Question 2

Myopia

Answer 2

Short sightedness

Vision is better for near than for further away

Question 3

Myopia - positive/negative lens

Answer 3

Negative lens

Question 4

Myopia - concave/convex lens

Answer 4

Concave lens

Question 5

Myopia - relationship with the retina

Answer 5

Visual images come in to focus in front of the retina

- images focus too early

Question 6

Myopia - converges/diverges light?

Answer 6

Diverges

Question 7

Hypermetropia

Answer 7

Long sightedness

Vision is better for further away than near objects

Question 8

Hypermetropia - positive/negative lens

Answer 8

Positive lens

Question 9

Hypermetropia - concave/convex lens

Answer 9

Convex lens

Question 10

Hypermetropia - relationship with the retina

Answer 10

Visual images come into focus behind the retina

- images focus too late

Question 11

Hypermetropia - converges/diverges light

Answer 11

Converges

Question 12

Presbyopia - definition

Answer 12

Power loss due to age

Question 13

Presbyopia - positive/negative lens

Answer 13

Positive lens

Question 14

Presbyopia - concave/convex lens

Answer 14

Convex lens

Question 15

Accomodative esotropia

Answer 15

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

Question 16

Astigmatism - definition

Answer 16

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

Question 17

Astigmatism - clinical features

Answer 17

Constant blurred vision at all distances

Question 18

Diplopia

Answer 18

Double vision

Question 19

Horizontal diplopia

Answer 19

Images are side by side

Problem with LR or MR

Question 20

Vertical diplopia

Answer 20

Images are one on top of the other

Problem with SO, SR, IR, IO

Question 21

Esotropia - definition

Answer 21

Inward squint, convergent squint

Question 22

Esotropia - what movement do you see when covering good eye

Answer 22

Outward movement

Question 23

Exotropia - definition

Answer 23

Outward squint, divergent squint

Question 24

Exotropia - what movement do you see when covering good eye

Answer 24

Inward movement

Question 25

Hypertropia - definition

Answer 25

High eye

Question 26

Hypertropia - what do you see when covering good eye

Answer 26

Downward movement

Question 27

Hypotropia - definition

Answer 27

Low eye

Question 28

Hypotropia - what do you see when covering good eye

Answer 28

Upward movement

Question 29

Visual field pathway

Answer 29

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

Question 30

Visual field defect

Answer 30

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

Question 31

Optic nerve defect - cause

Answer 31

Ischaemic optic neuropathy Optic neuritis Tumours

Question 32

Optic chiasm defect - cause

Answer 32

Pituitary tumour

Question 33

Optic tracts and optic radiation defect - cause

Answer 33

Tumours | Demyelination

Question 34

Occipital cortex - cause

Answer 34

``` Vascular disease (CVA) Demyelination ```

Question 35

Optic nerve problem - patients vision

Answer 35

Can't see at all in the affected eye

Question 36

Optic chiasm problem - patients vision

Answer 36

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

Question 37

Optic tract / optic radiation problem - patients vision

Answer 37

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

Question 38

Occipital cortex problem - patients vision

Answer 38

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

Question 39

Sudden vision loss - causes

Answer 39

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

Question 40

Gradual visual loss - causes

Answer 40

``` Cataract Dry ARMD Refractive error Open angle glaucoma Diabetic retinopathy ```