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Low Vision > MT 1 > Flashcards

MT 1 Flashcards

1
Q

What is LV

A

Reduced BCVA Or field loss and the need of lighting or a device

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2
Q

Standards for LV

A

20/200 snellen in best eye. 20/100 loggmar with 20/126 0r 20/160 line. OR less than 20 degrees usable VF.

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3
Q

Standard for VI

A

20/70 or worse

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4
Q

VI most common causes in adults

A

Cataracts, ARMD, glaucoma, DR.

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5
Q

Cause of VI in kids

A

Cortical impairment, OA, hereditary retinal dz, etc

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6
Q

20/100 in kids or better and 20/50 in Adults

A

No devices needed. Consider an Add

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7
Q

20/1,000 in kids and 20/400 in adults

A

Brail.

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8
Q

Photosensitivity caused by…

A

aniridia, glaucoma, albinism, achormatopsia, retinal dystrophy, conceal dystrophies

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9
Q

Color vision caused by…

A

chromatopsia, cone dystrophies, optic nerve disease

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10
Q

Contrast caused by

A

cataracts, glaucoma, retinal dystrophies, corneal dystrophies

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11
Q

Nystagmus

A

Caused by all early onset conditions affecting foveal pathway

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12
Q

What does VI in infants impact

A

fine and gross motor skills, cognitive development, socialization and communication

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13
Q

Walking in VI kids

A

18-24 months. Normal child? 9 and 12 months.

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14
Q

VI kids and language

A

Develop language at the same rate but their description is lacking.

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15
Q

Hearing and VI

A

Some VI kids will have reduced auditory acuity as they do not have visual cues for partly auditory communication. However, those that have VI early will increase hearing and motor skills.

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16
Q

Feelings and VI

A

VI cannot see nonverbal communication which shows feelings.

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17
Q

Transparecny

A

VI may not be aware of their facial expressions.

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18
Q

Cognitive development

A

Severe VI can make it difficult to grab conceptual concepts such as colors, 3D, figure ground relationships, size and shape characteristics.

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19
Q

Literacy and VI

A

Children with VI are at risk for becoming low achieving in reading. Braille and auditory users generally have higher literacy than children who are print readers

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20
Q

What VI groups is at greatest risk for literacy problems

A

Moderate (20/100-20/400)

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21
Q

Brightfield Magnifiers

A

Great for kids with 20/250 or better

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22
Q

Bioptic Driving Law

A

VI (20/70-20/200) can have a restricted drivers license with bioptic device.

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23
Q

Aging and LV

A

Very slow exam pace.

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24
Q

LV Case Hx

A
  1. Educate/clarify purpose of exam 2. Review underlying condition 3. Evaluate all areas of patient function that may impact adaption to vision loss 4. clearly outline goals/expectations
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25
Q

ADL

A

Need to understand patients life to understand vision needs.

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26
Q

What qualities indicate good prognosis with low vision adi

A

independently motivate, good cognition, previous success with low vision aid. 20/800 or better vision, positive self image, long standing stable condition

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27
Q

How different should near and far be?

A

one line

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28
Q

Refraction of LV patient

A

trial frame and retinoscopy best!

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29
Q

JND from BCVA

A

20 ft. snellen denometer/100.

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30
Q

Prescribing for near

A

Need 2x mag above acuity threshold to read comfortably.

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31
Q

Near add for pre-presbyopes

A

Use relative distance magnification

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32
Q

Adds for kids

A

No WOW factor. Increase comfort in long term.

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33
Q

Contrast threshold

A

The lowest contrast a patient can recognize optotypes. Normally a precent.

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34
Q

Contrast reserve

A

Ratio of contrast of an object to contrast threshold of the patient.

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35
Q

When contrast reserve falls below what will the patient have reduced functional deficits?

A

10/1

36
Q

Bailey Lovie Chart

A

Measure VA at 10% contrast. Normal patient will drop 2 lines. Have optotype change.

37
Q

Pelt-Robison chart

A

One size optotype with changing contrast. Test at twice the acuity threshold of the patient. VA deficits with 5% CT or greater.

38
Q

Which Contrast test is better?

A

Bailey love for showing contrast drop off with early stage disease/cataracts.

39
Q

Improving contrast sensitivity

A

increase magnification, increase lighting, etc.

40
Q

Why test BV on low vision patients?

A

May need to teach them to suppress bad eye or if nearly equal acuity need to teach them binocular summation.

41
Q

Binocular challenges with working close

A

Have mergence and accommodation needs when working at close working distance. Can use lenses and BI prism.

42
Q

Testing stereopsis in LV

A

Use a local test (global is rare in LV population)

43
Q

VF testing

A

Binocular fields are more relevant in a low vision exam. Testing is challenging due to poor fixation. Need a big fixation target. Need for legal blindness, mobility, driving, central vision tasks.

44
Q

How to test VF in LV by standards

A

Goldmann II4e target. 30-2 or 24-3 used.

45
Q

How to test VF if goldman not available?

A

Can do confrontation but use FW. Must present in more fields.

46
Q

Tangent screen and campimeter

A

Test patient at 1m and then move patient back to 2m. Should expand twice the original size.

47
Q

Macular Testing

A

White on black gives better testability for LV patients. Can also use penlight against the back to create a kinetic mapping stimulus.

48
Q

Macular testing condition

A

May fixate with pseudo fovea.

49
Q

Scotoma and reading

A

scotoma to the right of fixation make it difficult to read. Scotia to the left make it hard to saccade to next line.

50
Q

Definition of VA

A

The threshold to discriminate a small object or detail of high contrast

51
Q

Va is an _____ measure expressed in _____ terms

A

Angular, linear. Typically based on viewing distance and the distance the target subtends 5 arc min.

52
Q

Types of VA

A
  1. Minimum detectable 2. Minimal resolution 3. Recognition 4. hyperacuity
53
Q

Hyperacuity boundaries

A

Can get down to 3-8 arc seconds. Up to 10x finer than resolution.

54
Q

Levels of VA

A

NLP, LP, L perception with projection, HM, quantified va.

55
Q

Legal blindness

A

snellen is 20/200. 20/125 or worse with logmar. VF of 20 degrees or less

56
Q

VF blindness when no goldman

A

Can use mean deviation of -22 db or worse.

57
Q

Patients with 20/40-20/70

A

Not designated as VI but have driver restrictions.

58
Q

Hyperacidity measure in LV

A

A measure where hyperacidity result is better than VA suggests that the patient has some macular function.

59
Q

H54.8

A

The code you should always code first with a LV patient.

60
Q

Snellen acuity

A

biased for a normal visual acuity as number of letters decrease and there are only three lines between 20/100 and 20/400.

61
Q

LogMar demand change

A

Going up or down the chart by 3 lines changes the demand by a factor of 2.

62
Q

Demand from one line to another on LogMar chart

A

0.1

63
Q

VA on logera with +/-

A

Each character is 0.02. If you get extra it decrease. If you get less it adds.

64
Q

Fein bloom chart

A

Calibrated in feet. Can measure acuity for much higher demands. Up to 20/14,000.

65
Q

How close can test distance be in feinbloom

A

1 foot. Typically only have one character for the low demand lines.

66
Q

Freiburg visual acuity test (FrACT)

A

A computer based system based on the orientation of the C’s. Has low demands such as feinbloom.

67
Q

Berkeley Rudimentary Vision Test (BRVT)

A

Paddles with tumbling E’s on one card, gratings, and squares. Show at 100 or 25 cm. Document which one they can see and at what distance.

68
Q

Chart options

A

Printed on a screen, printed on paper or cardboard, displayed on a device, projected directly on the retina.

69
Q

Reverse contrast charts

A

Can convert black letter on a white background to white on black

70
Q

Color contrast

A

Such as yellow on blue or blue on yellow.

71
Q

What does improved VA on reversed contrast indicate

A

Need for tinted spectacles or goggles for use at far and magnifying devices for use at near.

72
Q

Grating

A

Must identify the orientation

73
Q

Landolt C

A

Can be 20-25% better as resolution and not recognition.

74
Q

Lighthouse Flash Cards

A

Outdated pictures and do not blur equally.

75
Q

Lighthouse Game card

A

Ask the patient to read. Increases the cognitive load.

76
Q

Snellen denominater

A

The distance that the optotype subtends five arc minutes.

77
Q

Half of JND

A

Power of individual plus and minus sphere bracketing lenses. Also power of cylinder test lenses and JCC lens.

78
Q

Full JND

A

Power of individual plus and minus cylinder bracketing lenses

79
Q

Going from 100-20 feet what is the change in MAR

A

It will be 5x greater.

80
Q

Spatial Frequency

A

Square wave or line is one dark and one bright. An E has 2.5 cycles tall.

81
Q

Threshold measure of spatial frequency

A

One cycle is twice the MAR. In cpd.

82
Q

Preferred method for recording near VA for low vision patients

A

M notion.

83
Q

Afocal telescope

A

Will increase the angular subtense without changing vergence

84
Q

RIM

A

RDM X RSMx LIM

85
Q

LIM for afocal

A

1/1-tFobj. Will always be greater than one.

86
Q

Magnification issue in LV

A

Size of object patient can see/size of object patient needs to see.

Low Vision (4 decks)

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