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Refracting Skills > unit 1 > Flashcards

unit 1 Flashcards

1
Q

Refracting Equipment

A

Phoropter
Trial lenses
Retinoscope
Visual acuitu charts
Automated refraction equpiment

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2
Q

Referrals from OPTICIANS

A

An optician must use their professional judgment to assess any indication or complication that arises during a refraction for referral to another regulated health professional

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3
Q

For a rx to be valid it must be a duplication of a pxs existing glasses or contain…

A

The name/identifier of the prescriber
The patients name
The patients rx
The date of examination

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4
Q

When duplication existing glasses..

A

It is to be noted on the patents record that it is a duplication and the optician should confirm the suitability of the prescriptions to a patient

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5
Q

What does an Optician have the duty to do?

A

Inform their patients of the importance of a regular eye exam and recommend regular testing as appropriate

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6
Q

When should a child have their first EE

A

Between 6-9 months

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7
Q

How many EE should be done between the ages 2-5

A

At least 1

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8
Q

When should healthy 19-40 have an EE

A

At least every 10 years

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9
Q

When should healthy 41-55 have an EE

A

At least every 5 years

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10
Q

When should healthy 56-65 have an EE

A

At least every 3 years

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11
Q

When should pxs over 65 have EE

A

At least every 2 years

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12
Q

Pxs at high risk over age 40 should have an EE

A

At least every 3 years

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13
Q

pxs at high risk over age 50 should have an EE

A

At least every 2 years

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14
Q

pxs at high risk over age 60 should have an EE

A

At lleast once a year

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15
Q

Canadians at higher risk

A

-People w diabetes, thyroid disease, rheumatological diseases including lupus
-People of african or hispanic descent
-Anyone prone to high IOP
-Anyone with a family history of glaucoma, cataract, macular degeneration or retinal detachement
-Anyone w a previous eye injury
-Ppl taking certain medications (plaquenil, prednisonse, ethambutol)

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16
Q

Fundamental concepts

A

Index of refraction
Fundamental paraxial equation I=n/L
Prentices rule

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17
Q

Index of refraction formula

A

n= Speed of light in air / speed of light in substance

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18
Q

Substances with higher index will have/do

A

More dense
Slows down the light

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19
Q

Glass index..

A

1.52

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20
Q

Air index

A

1.00

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21
Q

Aqueous and vitreous index

A

1.34

22
Q

Cornea index

A

1.376

23
Q

Water index

A

1.33

24
Q

Snells law / refraction of light

A

n sin I = n’ sin I’
I= angle of incidence
n’ refractive index of second medium
I’ angle of refraction in second medium

25
Q

Fundamental paraxial equation

A

L’ = L + F
L= object vergence
F= lens power
L’= image vergence

26
Q

What does the fundamental paraxial equation do

A

Determine the position of an image formed by an optical device
Applied to thin lenses/single refracting service

27
Q

What does paraxial stand for

A

Rays near the axis

28
Q

Vergence power of a lens formual

A

U + P = V
U= vergence power of object rays
P= power of lens in diopters
V= vergence power of image rays

29
Q

What does vergence power of a lens equation mean

A

Amount that a lens or optical system converges or diverges the light

30
Q

Distance of the object from the lens formula

A

U= 1/u
U= vergence of the object rays
u= distance of the object from the lens (m)

31
Q

Distance of the image from the lens formula

A

V=1/v
V= vergence of the image rays
v= distance of the image from the lens

32
Q

Focal length formula

A

P= 1/f
P= power of the lens
f= focal length

33
Q

prentices rule
p=cF

A

USed when a rx is not centered properly. Meaning oc is not in the requested area

34
Q

Prentices formula

A

Prism= F x decentration (mm) / 10

35
Q

Emmetropia

A

An eye that does not need any correction / no refraction error

36
Q

Ametropia

A

A deviation from emmetropia

37
Q

Myopia

A

-The second focal point F’e lies in front of the centre of the macula “short sight”
-The far point lies at a finite distance in front of the eye - the position at which an object has to be placed for an eye to see it clearly
-Corrected using negative lenses

38
Q

Hypermetropia

A

-The second focal point F’ lies behind the centre of the macula “long sight”
-The far point lies at a finite distance behind the eye
-Corrected using positive lenses

39
Q

Astigmatism

A

-Needs a corrective lens with a power that differs along the principal meridians of the lens

40
Q

Astigmatic ametropia

A

Can originate at the cornea (corneal astigmatism), crystaline lens (lenticular astigmatism) or combination

41
Q

When astigmatism is measured through an EE what does it mean

A

It measures the total astigmatism - does not differentiate between corneal and lenticular

42
Q

Can a keratometer measure corneal astigmatism?

A

yes

43
Q

With the rule astigmatism

A

Occurs when the flattest corneal meridian is near the horizontal
-Axis of the correcting cly closest to 180

44
Q

Against the rule astigmatism

A

Occurs when the flattest corneal meridian is closer to the vertical
-axis is closest to 90

45
Q

Regular astigmatism

A

Refractive error is constant over the refracting surface

46
Q

Irregular astigmatism

A

Refractice error varies over the refracting surface

47
Q

Possible causes of irregulr astigmatism

A

-Corneal scars
-Pterygium
-Dislocation of the crystalline lens
-Kerataconus
-Lenticonus
-Eyelid lesions that press on the cornea
-cataract

48
Q

when should a healthy 36 year old asian px get an EE

A

at least every 10 years

49
Q

when should a 55 year old diabetic get an EE

A

at least every 2 years

50
Q

when should a healthy 70 year old caucasion px get an ee

A

At least every 2 years

51
Q

when should a healthy 45 year old hispanic get an ee

A

at least every 3 years

52
Q

when should a 55 year old px on plaquenil get an ee

A

at least every 2 years

Refracting Skills (7 decks)

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