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Ophthalmology > Low vision and visual rehabilitation > Flashcards

Low vision and visual rehabilitation Flashcards

1
Q

What % of patients that go to LVA are under 16 years old?

A

5%

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2
Q

What 6 conditions/reasons do children go to LVA for?

A
  1. Congenital cataracts - most common
  2. Optic atrophy (often 2o)
  3. Albinism
  4. Buphthalmos
  5. Myopia
  6. Retinopathy of prematurity
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3
Q

What % of patients that go to LVA are adults in the employable age group?

A

25%

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4
Q

What 6 conditions/reasons do adults go to LVA for?

A
  1. DR
  2. Myopia
  3. Uveitis
  4. Corneal dystrophies
  5. Macular degenerations
  6. Retinitis pigmentosa
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5
Q

What are 2 clinical features of congenital cataracts in children?

A
  1. Occurs in first few months of life

2. Absence of red reflex

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6
Q

Why is it important to address congenital cataracts in children?

A

Need to stimulate development of visual pathways

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7
Q

What is buphthalmos in children?

A

Congenital glaucoma – problem with drainage angle so pressure rises, and eye expands, leading to enlargement of eyeball

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8
Q

Are children usually born hyperopic or myopic?

A

Hyperopic

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9
Q

What happens to shape of eye as a child grows up?

A

Elongates

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10
Q

What are 4 common causes of visual impairment in the elderly?

A
  1. Age related macular degeneration (dry/wet) – most common
  2. Glaucoma
  3. Inoperable cataract
  4. DR and maculopathies
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11
Q

What % of LVA patients are retired/elderly age group?

A

70%

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12
Q

What are the 7 principles of vision assessment?

A
  1. Clear diagnosis and make sure patient has a good understanding of their problem and realistic expectations of what optometrists can do for them
  2. Identify patients practical needs/assess expectations e.g. problems with reading/watching TV/cooking etc
  3. Record distance unaided vision i.e. Snellen chart
  4. Retinoscopy – objectively assessing someones prescription i.e. holding lens in front of the eye + shine light with torch
  5. Subjective refraction – ask patient to tell you if different lens have any benefit etc
  6. Near vision assessment e.g. N10 (size of print) at 25cm with +4.00D add
  7. Unit magnification assessment
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13
Q

What is unit magnification? How does it work?

4

A
  1. Determines patients distance refraction/correction
  2. Ask patient to view reading chart at 25 cm, then determine best near acuity at this range e.g. N10
  3. Ask patient what size is required for desired tasks
  4. Calculate magnification required to achieve this
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14
Q

What are logMAR charts? How is it different to Snellen?

“

A
  1. Used more in research/clinical setting – good for people with visual impairment.
  2. More subjective – 5 letters per line and decrease down in size evenly in a logarithmic fashion so it is more fair. However there is more crowding as you go further down.
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15
Q

What is a General referral GOS (18) form?

4

A
  1. Standard referral for patients from the community to hospital i.e. optometrists refer to hospital eye service via GP
  2. Referral by optometrist: sign of injury, disease or abnormality and treatment or further investigation required, or unsatisfactory level of VA even with corrective lenses
  3. Information by GP: Screening and monitoring diabetes and patients with glaucoma
  4. Referral implies transfer of responsibility to GP
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16
Q

If urgent treatment is needed, how does an optometrist directly refer to hospital?

A

Directly refers, but needs to notify GP by phone/fax

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17
Q

What are the 2 different sections of GOS (18)?

A

Section 1 - Completed by optometrist

a. Patients details
b. Sight test details and acuities
c. Disc appearance, IOPS and visual fields
d. Points of interest

Section 2 – complete by GP

a. Relevant clinical and social history
b. BP, urinalysis, provisional diagnosis

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18
Q

What are the 3 specific visual impairment referrals?

A

LVI – letter of visual impairment
RVI – referral of visual impairment
CVI – certificate of visual impairment

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19
Q

What is the definition of visual impairment?

A

A person who is ‘substantially and permanently handicapped’ by defective vision caused through congenital defect, illness or injury

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20
Q

What are the objective definitions of visual impairment (3)?

A

VA – 3/60 to 6/60 on Snellen chart
OR
Up to 6/24 with moderate fields contraction
OR
VA 6/18 or better if severe field loss (advanced glaucoma, retinitis pigmentosa or hemianopia)

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21
Q

What is an LVI (3)?

A
  1. Referral form for use by optometrists or clinicians outside the HES
  2. Given to patients with significant difficulties to help seek advice from a council with social services (SS) responsibilities
  3. Patient fills in the details
22
Q

What is an RVI (2)?

A
  1. Can be used by non-ophthalmic staff

2. Can be used to allow patient to access social services

23
Q

What is CVI (4)?

A
  1. Document patients level of vision – certificate of a person as sight impaired or severely sight impaired/blind
  2. Patients can volunteer to have it done
  3. Gives them access to social services
  4. 3 parts:
    a. Opthalmologist i.e. visual function
    b. Other relevant factors e.g. lives alone, hearing, mobility
    c. Patient consent to registration
24
Q

What is vision (2)?

A
  1. The level of vision that an eye can resolve unaided
  2. Determined by the size of the smallest line of letters or symbols on the test chart that can be read without any form of optical correction in place
25
Q

What is visual acuity (2)?

A
  1. A measure of the eye’s ability to resolve fine detail with the optimum optical correction in place
  2. Determined by the size of the smallest line of letters or symbols on the test chart that can be read after any defects of focusing, other than aberrations have been corrected
26
Q

What is accomodation?

A

The ability of lens to change the shape resulting in change of power

27
Q

How does the lens accomodate (3)?

A
  1. Ciliary muscle contracts
  2. Zonules relax
  3. Lens assume a more convex shape
28
Q

What is presbyopia?

A

With age, the crystaline lens undergoes sclerosis resulting in accommodative ability causing an inability to focus on near objects

29
Q

What are 2 methods of testing visual acuity?

A
  1. Snellen chart

2. LogMAR chart

30
Q

When measuring near vision, what does N6 mean?

A 
N = notation
6 = size of print
31
Q

What are the 3 main refractive components of the optical system?

A
  1. Cornea
  2. Lens
  3. Axial length
32
Q

What is a dioptre?

A

The unit of measurement of the optical power of a lens or mirror
It describes an ability to bend or refract rays of light so light is focused accurately onto the fovea

33
Q

What does emmetropia mean?

A

Optically perfect eye

34
Q

What are the dioptres of the cornea and lens, and axial length in an emmetropic eye?

A

Cornea = 40D
Lens = 20D
Axial length = 22.22mm

35
Q

What is ametropia?

A

One or more of the optical parameters are ‘less than perfect’ and therefore an optical or focusing error occurs

36
Q

What happens in myopia?

A

Light is focused in front of the retina

short-sightedness

37
Q

What are the 2 types of myopia?

A
  1. Refractive myopia
    - Effective power of eye too strong >60D
  2. Axial myopia
    - Eye is too long, >22.22mm
    - Corrected with divergent lenses
38
Q

What type of lens corrects myopia and how does it work?

A

Divergent

Light rays spread out and focus pushed back on to retina

39
Q

What happens in hypermetropia?

A

Light is focused behind the retina

40
Q

What are the 2 types of hypermetropia?

A
  1. Refractive hypermetropia
    - Effective power of eye too weak, <60D
  2. Axial hypermetropia
    - Eye is too short, <22.22mm
    - Corrected with convergent lens
41
Q

What lens corrects hypermetropia and how does it work?

A

Convergent

Light rays contracted and focus pulled forward on to retina

42
Q

What is an astigmatism?

A

Eye is shaped like a rugby ball - symmetrical in shape in all but one direction. Therefore light will be refracted in the same manner over all most of the eye, forming a point focus as normal. Light striking the eye in the direction of the asymmetry will be refracted in a different manner and thus a second point focus will be formed

43
Q

What is the correction of the astigmatism?

A

A convergent or divergent lens will correct the main refraction error.
An additional lens with power in one direction only will then be used to correct the residual astigmatic error - a cylindrical or toroidal lens

44
Q

What are 2 alternative methods of correction to glasses?

A
  1. Contact lenses

2. Refractive surgery

45
Q

What is the pinhole used for?How does the pinhole work?

A

Pinhole can help to differentiate between reduced VA due to uncorrected refractive error and a pathological cause.

It reduces the blur circle and induces a point focus within the eye

46
Q

If VA is corrected with pinhole, what does this mean?

A

There is uncorrected refractive error causing the redeuction in VA

47
Q

If a VA is not corrected with pinhole, what does it mean?

A

Underlying pathological cause

48
Q

What are 5 advantages of soft contact lenses?

A
  1. Flexible
  2. Good initial comfort
  3. Larger diameter incurs secure fit
  4. Safer for sport
  5. May be used for extended wear
49
Q

What are 7 advantages of rigid gas permeable lenses?

A
  1. Fixed shape and durable
  2. Good for all-day wear
  3. Smaller diameter incurs less risk of hypoxia
  4. Creates smoother ocular surface therefore better
  5. Visual result for irregular corneas and high astigmatism
  6. Easy to clean
  7. Good VA if large elvels of astigmatism
50
Q

What are 4 disadvantages of soft contact lenses?

A
  1. Splits easily
  2. Depositions from tear
  3. More expensive
  4. Dehydrates if left out of the solution
51
Q

What are 2 disadvantages of rigid gas permeable lenses?

A
  1. Poor initial comfort

2. Smaller diameter therefore prone to fall out of eye

Ophthalmology (12 decks)

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