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YEAR 3 > LOW VISION > Flashcards

LOW VISION Flashcards

(106 cards)

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1
Q

Define low vision

A

Significant visual impairment; cannot be fully corrected and interferes with daily life. Caused by conditions such as AMD and requires extra help such as magnification/lighting/optical aids.

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2
Q

SSI National Assistance Act definition of low vision

A

So blind they cannot do any work for which eyesight is essential.
6/120 with full visual field
Between 6/120 and 6/60 with severely restricted field of vision

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3
Q

6 psychological stages of vision loss

A
  1. Shock
  2. Denial
  3. Anger
  4. Bargaining
  5. Depression
  6. Acceptance
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4
Q

Who would you refer to for help getting out and about safely?

A

Rehabilitation officer

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5
Q

Inverse square law of illumination

A

States light gets brighter when source is moved closer; halving the distance = 4x brighter

E =I / d2

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6
Q

3 major causes of sight loss in the UK

A

-AMD
-Diabetic retinopathy
-Glaucoma

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7
Q

Low vision services

A

-RNIB
-Local charities
-Social services
-Occupational therapist
-GP
-HES
-Rehabilitation services

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8
Q

Advantages of EVES

A

-High mag
-No aberrations
-Easy focus
-Variable mag
-Hands free
-Improved FOV
-Comfortable
-Control brightness

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9
Q

Disadvantages of EVES

A

-Expensive
-Technophobic
-Training
-Complex to fix
-Trailing leads
-Not robust
-Larger means not portable
-Specialist installation

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10
Q

Magnification used for EVES

A

Transverse magnification
M = screen image size / original object size

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11
Q

Optical principles met for nominal mag

A

-Correct object position
-Correct eye to lens distance
-Relaxed accommodation
-Used of corrective lenses

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12
Q

Impairments

A

A problem in body function or structure; such as significant loss or abnormality

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13
Q

Activity limitations

A

Difficulties an individual may have in executing tasks

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14
Q

Participation restrictions

A

Problems an individual may experience in life situations

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15
Q

Performance qualifier

A

Describes what an individual does in their current environment; including with the use of assistive devices/ support

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16
Q

Capacity qualifier

A

Describes an individuals ability to execute a task or action in a standardised environment; without use of assistance

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17
Q

Hand mag training

A

-Hold mag close to eye
-Bring material close until clear
-Recommend good lighting
-Encourage build up time
-Support arms/ stand
-Use corrective lenses

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18
Q

Advantages of nominal mag

A

-Portability
-Variable use
-Availability

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19
Q

Disadvantages of nominal mag

A

-Poor dexterity
-Limited field of view
-Practice

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20
Q

Four non-optical aids to help everyday life;

A

Liquid Level Indicators;
-clips on to edge
-vibrates / beeps
-prevents spills

Talking Scales;
-weighs food
-speaks out loud
-allows independent cooking

Tactile Markers;
-places on appliances
-allows to identify settings

High cotrast;
-utensils/plates/cups
-bold, large print, contrasting colours
-improves visibility

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21
Q

Amsler chart instructions

A

-Wear near correction
-Sit in well lit area
-Place chart around 30cm
-Test each eye individually
-Focus on central dot
-User peripheral to observe grid
-Wavy/ blurred/ missing?
-Repeat with other eye
-Test daily
-Act on any changes

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22
Q

Define visual field

A

The entire area that can be seen by he eye when looking straight ahead without moving the eyes

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23
Q

Pelli-Robson chart

A

-Provides functional/ realistic assessment of a low vision patients capability; everyday tasks
-Measures contrast sensitivity not VA’s

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24
Q

Bailey-Lovie chart

A

-Measures VA’s
-LogMAR scale
-Same number of letters per line
-Equal spacing
-Standardised crowding
-Sloan letters
-More accurate then snellen
-Easy to track

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25
Luminous efficiency
The quantity of light created by a given electrical input. It explains how many lumens of luminous intensity are produced by 1 watt of electrical power
26
Luminous flux
The rate of the flow of light in one direction. Baring in mind that light from a source travels in all directions
27
Discomfort glare
Stray light which reduces visual comfort but is not responsible for reduction in VA’s. Normally associated with differing levels of illuminance in the visual field.
28
Disability glare
Stray light that interferes with visual performance. Normally this glare which affects low vision patients. Predominantly due to scatter and fluorescence in the ocular media
29
Estimated magnification formula
Mag = acuity achieved / acuity required
30
Calculate angular magnification
Step 1: L = 1 / l L’ = L + F Step 2: AM = qL / 1 - dL
31
Calculate accommodation
Step 1: l’ = n’ / L’ le = l1’ - d Step 2: Le = 1 / le
32
Calculate nominal magnification
Mnom = F / 4
33
Calculate max magnification
Mmax = F / 4 + 1
34
Aniridia
Absence of the irris
35
Micropthalmia
Abnormally small eyeballs
36
Diabetic retinopathy
Signs: -cotton wool spots -neovascularisation -Haemorrages Visual function changes: -flashes/floaters -blurred vision -empty areas in vision -central vision loss
37
Explain terrestrial telecope
A telescope used to view objects, typically in the distance such as bus numbers/ sights. Often handheld or spectacle mounted.
38
Explain the term reading cap
A high plus lens that is attached to the front of a telescope to allow the user to focus on near tasks such as reading. Allows hand free magnified near vision when mounted.
39
Explain telemicroscope
A telescope system to aid low vision which is designed to provide mag for closer working distances. Usually spectacle mounted but can be on a stand for hands free use. Can offer binocular/ minocular vision depending on the design
40
Form used to certify someone severely sight impaired
Certification of Visual Impairment (CIV)
41
Who can certify someone as SI or SSI
Ophthalmologist
42
Who receives copies of the certification form
-Patient for records -GP to continue care -Local social services to support / add to register
43
Symbol cane
-Indicates the user has visual impairment -Acts as a symbol to others -Features; small, lightweight, he’d in front of body, usually white
44
Long cane
-Detects obstacles/ steps/ surface changes -Mobility aid used for independent navigation -Features; long, often rolling/ tapping tip, sweeps ground ahead
45
Two ways a patient can carry the symbol cane
1. In front of the body -Held vertically or at a slight angle -Visible to others -Commonly used in crowded areas 2. Worn on arm using strap -Attached too the wrist/ arm -Allows to hang visible whilst keeping hands free -Still acts as a visible signal
46
How to see image clearly with stand magnifier
-Accurate positioning -Good lighting -Direct lighting -Inverse square law of illumination -Hold directly above
47
Why would the use of a hand/stand magnifier help someone with AMD
Provides enlarged images of near objects which help compensate for the loss of central vision caused by AMD
48
Benefits of high add reading spectacles
-Hand free -Binocular use -Wider field of view -Lightweight
49
Limitations of using high add magnification
-Short working distance -Postural strain -Difficult binocular use at high powers -Limited field of depth
50
Advantages of hand magnifiers
-Portable -Lightweight -Illuminated for better contrast -Inexpensive -Wide range of mag -Easy to use -No fitting required -Suitable for both eyes -With or without spectacles
51
Starting magnification formula
Starting mag = current NVA / target NVA
52
Why is contact sensitivity be considered useful for a low vision patient?
-Cataracts and AMD reduce contrast sensitivity -VA testing alone does not reveal reduced function in low contrast conditions -Helps identify difficulties in real world tasks -Justifies use of aids with contrast/ illumination -Assesses functional impact pathology
53
Name one other way the illuminance of a lamp can be increased
Use a higher intensity bulb
54
A cataract patient has difficulty reading a glossy magazine with a task lamp. Why?
-Glossy surfaces reflect light causing glare -Cataracts scatter incoming light making glare worse -Contrast may be reduced -Recommend using a matte finish
55
Name a magnifier with light-gathering properties
A bright field dome magnifier
56
State two ways a patient can reduce glare caused by sun
-Wrap around tinted lenses -Wear a wide-brimmed hat
57
Explain the purpose of the LVA form and who completes it
-LVA form is a clinical record detailing patients assessment, goals, recommended aids and outcomes -Competed by optometrist/ dispensing optician after low vision assessment
58
Disadvantages of spectacle magnifiers
-Hands free use -Lightweight -Cosmetically acceptable
59
Short notes on dry AMD
-Most common type of AMD -Affects macular; central vision loss -Caused by drusen accumulation -Gradual -No leakage -Often bilateral -Central scotoma develops -No cure -Amsler grid to monitor -May progress to wet -AREDS may slow progression -Causes difficulty in low contrast conditions
60
Short notes on keratoconus
-Non inflammatory thinning of the cornea -Leads to cone shaped cornea -Irregular astigmatism -Commonly present in adolescence -Vision becomes increasingly blurred -Can be bilateral -Contact lenses (RP’s) neutralise irregular astigmatism to provide a smooth surface
61
Short notes on iris coloboma
-Congenital defect where part of iris is missing -May be associated with other ocular colobomas -Causes glare and photophobia -VA’s reduced -Usually detected at birth -Tinted/ prosthetic contact lenses to improve cosmesis and reduce glare caused
62
Short notes on albinism
-Group of genetic conditions affecting melanin production -Ocular signs include nystagmus and reduced VA’s -Causes photophobia due to lack or pigment -High refractive errors are common -May have strabismus -Tinted contact lenses reduce scatter and photophobia
63
Benefits of registering as SSI
-Disabled persons railcard -Free NHS eye exams -Blue badge parking -Council tax reduction -Free/reduced TV license -Assistance from social services -Bus pass
64
Cosine law of illumination
Light directly above (0 degrees) gives max illumination
65
How can a telescope be used to increase field of view
-Reverse telescope technique -Minifies the image -Useful in tunnel vision cases -Allows user to spot objects in the periphery -Reduced detail but increased navigational awareness
66
How can a patient with central vision loss improve TV viewing without optical aids
-Sit closer to screen; relative distance magnification -Use a larger screen; relative size magnification
67
If a patient prefers old spectacles - what action should you take
-Confirm vision is better with old Rx -Check old Rx -Consider re-prescribing old Rx -Document patient referent -Provide explanation of limitations of newer Rx
68
Two ways power can be supplied to an illumination stand magnifier
-Battery powered -Main
69
3 reasons why high-power magnifiers are difficult to use
-Very short focal length -Narrow field of view -Requires precise positioning
70
State the purpose of the low vision assessment
-Understand functional vision/ daily challenges -Explore different aids -Measure vision more accurately then basic sight test -Offers support/ information -Tailor a plan for independence
71
Disadvantages of Snellen chart for low vision
-Unqual letters per line -Irregular size progression -Crowding effect not standardised -Too few lines or accurate scoring -Low resolution -Poor repeatability
72
Disadvantages of near vision telescopes
-Short working distance -Narrow field of view -Bulky/ heavy -Difficult to align -Expensive -Requires training
73
Two forms of magnification
1. Relative size magnification (larger print) 2. Relative distance magnification (move closer to TV)
74
Which form is completed for certification and can DO’s sign it?
-CVI; certificate of vision impairment -Only ophthalmologist can sign -DO’s cannot certify by can recommend
75
Optical aids for watching TV
-Monocular telescope -Reverse Galilean
76
Why may magnification be ineffective for someone with diabetic maculopathy
-Enlarging the mage pushed it onto the damaged area of retina -Severe central field loss -Magnification alone doesn’t improve contrast -Poor fixation stability -Causes frustration
77
Registration criteria for SI
-VA 3/60 to 6/60 with full field -VA 3/60-6/60 with restricted field -VA better than 6/60 with severe field constriciton
78
Registration required for SSI
-VA less than 3/60 with full field -VA 3/60-6/60 with very restricted field -VA better than 6/60 with severe field constriction
79
Additional advice to optimise EVES use
-Adjust brightness and contrast to comfort -Use correct working distance -Maintain consistent lighting -Clean screens -Train in freeze and zoom features -Use text to speech -Take regular breaks
80
Advantages of nominal use
-Simple to use -Accurate magnification -Comfortable for short tasks
81
Limitation of nominal use
-Fixed working distance -Require exact alignment -Narrow field of view -Not suited for prolonged reading
82
Example of activity limitations
1. Reading bills/ emails 2. Identifying bus numbers
83
Example of participation limitations
1. Baking for community events 2. Travelling independent to social outings
84
Why do magnifiers help with macular degeneration
-Enlarges image to stimulate functioning retinal areas -Allows use of eccentric viewing -Improves independence -May improve independence
85
Benefits of near telescopic systems
-Hight magnification -Improved posture -Can be spec mounted
86
Limitations of near telescopic systems
-Narrow field of view -Heavy -Expensive -Training required
87
Preferred retinal location
Using a functional peripheral area to fixate off centre
88
Eccentric fixation
Intentionally positioning gaze to use PRL instead of fovea
89
Steady eye strategy
Moving the target while keeping gaze steady
90
Features of wearable tech
-Text to speech -Facial recognition -Object recognition -Barcode scanning -Voice activation -Hands free operation
91
5 leading pathologies of SI/SSI in UK
-AMD -Diabetic eye disease -Glaucoma -Retinitis pigmentosa -Cataracts
92
Explain relative convergence
-Convergence required to fuse images at close working distance -Important in low vision -Must assess ability to maintain binocularity -If convergence insufficient then prism can be prescribed -Critical in high plus prescriptions
93
Short notes on Aphakia and CL benefit
-No crystalline lens -High hypermetropia -Poor image with specs -CLs provide better retinal image size -Centralised correction -Improved VA’s -Reduced aberrations -Useful post surgery -Better cosmetics
94
Short notes on Nystagmus and CLs benefits
-Involuntary eye movement -Reduced VA -CLs move with eye = stable image -CLs improve VAs -Minimise spec blur -Improved confidence -Improves binocular function
95
Visual changes in glaucoma
-Peripheral field loss -Delayed dark adaption -Glare sensitivity -Reduced contrast sensitivity -Patchy vision -Difficulty navigating -Advanced cases may affect central acuity. -Increased fall risk -Visual fatigue
96
Define scotoma
An area of partial alteration in the visual field
97
Define absolute scotoma
Area where no vision is present
98
Define relative scotoma
Area where vision is reduced but not completely absent
99
Define negative scotoma
Undetected by patient
100
Define positive scotoma
Detected by patient (appears as a dark or blurred area)
101
Define hemianopia
Loss of half the visual field
102
Advice for bar/ flat field magnifiers
-Place directly on flat page -Don’t tilt -Use strong task lighting -Move smoothly alone lines -Clean regularly -Use finger to track -Slow scanning -Avoid use on curved pages -Hold reading material steady
103
Define exit image vergence
Vergence of light leaving a telescope system
104
Define distance cap
A lens allowing focus at a set near working distance
105
Define free working distance
Distance between the aid and the object
106
Galilean a focal setup explanation
-Place lenses at sum of focal lengths -Light enters parallel, exits parallel -Objective positive lens -Eyepiece negative lens -Ensures image is at infinity

YEAR 3 (3 decks)

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