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Low Vision > Key Terms & Definitions > Flashcards

Key Terms & Definitions Flashcards

1
Q

Definition of Low Vision

A

A person with Low Vision is someone who has a visual impairment where it cannot be remedied by conventional spectacles, contact lenses or medical intervention which causes restriction in one’s life.

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2
Q

National Assistance Act 1948 Definitions:

Blind/Severely Sight Impaired

A

‘So blind as to be unable to perform any work for which eyesight is essential’

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3
Q

National Assistance Act 1948 Definitions:

Partially Sighted

A

‘Substantially and permanently handicapped by defective vision caused by congenital or illness or injury’

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4
Q

Form for being registered sight impaired

A

CVI - Certificate of Visual Impairment

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5
Q

Leading causes of Sight Loss in the UK

A
  1. Uncorrected Refractive Error
  2. AMD
  3. Cataract
  4. Glaucoma
  5. Diabetic Retinopathy
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6
Q

Causes of SSI and SI in UK

A
  1. AMD
  2. Glaucoma
  3. Cataract
  4. Retinitis Pigmentosa
  5. Diabetic Eye Disease
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7
Q

Who can sign a CVI?

A

Ophthalmology Consultant

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8
Q

Classifications of SSI:

Group 1

A

Visual acuity below 3/60

a px who is 1/18 cannot be certified in group 1

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9
Q

Classifications of SSI:

Group 2

A

Visual Acuity between 3/60 and 6/60 and significant field defect

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10
Q

Classifications of SSI:

Group 3

A

Visual acuity better than 6/60 and a severe significant field defect, especially if in inferior field

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11
Q

Other factors considered during registration

A

How recent the visual impairment occurred
Age of diagnosis
Home/living situation1
Any additional impairments

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12
Q

Classifications of SI:

A

VA of 3/60 to 6/60 with full visual field
VA up to 6/24 with moderate reduction of visual field or with a central cloudiness/blur
VA 6/18 or better with gross field defect (retinitis pigmentosa and glaucoma)

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13
Q

Classification for infants and young children

A

Infant and young children with visual ocular abnormalities are certified SI unless obviously blind.

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14
Q

Pathway of registration

A
  1. DO, GP or OO identifies visual impairment and referred to eye clinic.
  2. Px seen by Consultant Ophthalmologist who performs tests. If eligible, the official documentation will be given.
  3. Signed CVI goes to: Office of National Statistics, GP and local authority.
  4. Local social services will contact for confidential registration & registration card
  5. Social Care and Rehabilitation Assessment is performed to identify needs and entitlements.
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15
Q

Long Cane:

A 
White
Mid-chest Height
Lightweight
Moved side to side in arc of body
Used for mobility
Can be fitted with roller tip
Informs others of impairment
Red portion = hearing impairment
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16
Q

Symbol Cane:

A 
White
Light weight
Not load bearing
Often foldable
Carried diagonally across chest
informs others of impairment
Red portion = hearing impairment
17
Q

Guide Cane:

A 
White
Shorter than long cane
Used by Px's with more useable vision
Provides support in unfamiliar environments
Used to find obstacles
18
Q

White Walking Stick

A 
White
Load bearing
Exact length is important
Used for mobility support
Fitted by a professional
Red Stripe = hearing impairment
19
Q

High Reading Addition/Spectacle Magnifiers:

Advantages

A

Hands free
Very wide field of view
Cosmetically & psychologically more accepted
Wide range available
No specialised equipment training required

20
Q

High Reading Addition/Spectacle Magnifiers:

Disadvantages

A

Requires prism control for +4.00D and above
Short working distance
More difficult to provide required illuminance
Total powers can be high = more expensive

21
Q

Acuity Reserve

A

2:1

required N/2 = aimed for N

22
Q

Metre Angle:

A

How many angles required of convergence for metres

23
Q

‘Rules of Thumb’

Spectacles Mounted Magnifiers

A

1 Base IN prism per dioptre of object to lens distance

24
Q

‘Rules of Thumb’

High Reading Addition

A

1 Base IN for every dioptre of ADD over +3.00D

25
Q

Amsler Chart: Structure

A

Grid of lines making squares
Central fixation point
Designed to measure central 10 degrees of visual field

26
Q

Amsler Chart: Use

A 
Well lit room/in day light
Held at 30cm
Wear NV correction
Each eye occluded in turn
Px should stare at fixation point
Px should report any lines that are distorted or missing
27
Q

Contrast Definition

A

Contrast is the difference in luminance or colour that makes an object discernible

28
Q

Why is contrast sensitivity measured?

A

Allows us to gauge visual performance under real world conditions
Allows us to predict the likely success of a LVA
Allows us to consider whether contrast advice is required/warranted

29
Q

What is Contrast Sensitivity

A

The lowest amount (threshold) of contrast that can be seen (resolved) by a patient.

30
Q

Three low contrast charts

A

Pelli-Robson Chart
Bailey Lovie Chart
VISTECH Chart

31
Q

Pelli Robson Chart

A

All letters same size
Tested at 1m
Eight rows
1 row has 2 sets of 3 letters
Each triplet of letters have same contrast
Contrast reduces in logarithmic progression
Contrast reduces across and down the chart
Contrast ranges from 89% to 0.5%

32
Q

VISTECH Chart

A

Five rows
Nine columns
Sine wave gratings/circular grating patterns
Decreases in contrast left to right
Increase in spacial frequency top to bottom
Forced choice
Used at 3m

33
Q

Snellen Chart:

Disadvantages

A 
Too few letters at lower acuities
Non-logarithmic design
No consistent ratio between letter size
Non consistent spacing = crowding
Inconsistent letter legibility
Measures high contrast only
Does not consider real life environments
Designed for use at 6m
Over estimates acuity if used at closer WD
Does not allow for estimates if mag requirements
34
Q

Bailey-Lovie Chart

Advantages

A

Logarithmic in design
Constant ratio of letter size
Line and letter spacing equivalent throughout
Can be used at any appropriate WD
Allows more accurate prediction of mag requirements
Each line has 5 letters to improve accuracy/reliability
Each letter has a score which improves accuracy

35
Q

What is a ‘spot task’

A

Survival task
Brief
Require little or no fluency
Example: pills, bills, cooker dials & cooker instructions

36
Q

What is a ‘sustained tasks’

A

Requires fluency

Example: reading for pleasure

37
Q

Hand Magnifiers:

Advantages

A

Relatively inexpensive
Socially accepted
Can be internally illuminated
Quite portable/lightweight

38
Q

Hand Magnifiers:

Disadvantages

A

Requires dexterity
Do not have both hands free
Low quality lens
Difficult to train & Px to replicate

Low Vision (2 decks)

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