unit 1 Flashcards by Megan Blomer

Refracting Equipment

Phoropter
Trial lenses
Retinoscope
Visual acuitu charts
Automated refraction equpiment

How well did you know this?

Not at all

Perfectly

Referrals from OPTICIANS

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

How well did you know this?

Not at all

Perfectly

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

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

How well did you know this?

Not at all

Perfectly

When duplication existing glasses..

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

How well did you know this?

Not at all

Perfectly

What does an Optician have the duty to do?

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

How well did you know this?

Not at all

Perfectly

When should a child have their first EE

Between 6-9 months

How well did you know this?

Not at all

Perfectly

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

At least 1

How well did you know this?

Not at all

Perfectly

When should healthy 19-40 have an EE

At least every 10 years

How well did you know this?

Not at all

Perfectly

When should healthy 41-55 have an EE

At least every 5 years

How well did you know this?

Not at all

Perfectly

When should healthy 56-65 have an EE

At least every 3 years

How well did you know this?

Not at all

Perfectly

When should pxs over 65 have EE

At least every 2 years

How well did you know this?

Not at all

Perfectly

Pxs at high risk over age 40 should have an EE

At least every 3 years

How well did you know this?

Not at all

Perfectly

pxs at high risk over age 50 should have an EE

At least every 2 years

How well did you know this?

Not at all

Perfectly

pxs at high risk over age 60 should have an EE

At lleast once a year

How well did you know this?

Not at all

Perfectly

Canadians at higher risk

-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)

How well did you know this?

Not at all

Perfectly

Fundamental concepts

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

How well did you know this?

Not at all

Perfectly

Index of refraction formula

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

How well did you know this?

Not at all

Perfectly

Substances with higher index will have/do

More dense
Slows down the light

How well did you know this?

Not at all

Perfectly

Glass index..

1.52

How well did you know this?

Not at all

Perfectly

Air index

1.00

How well did you know this?

Not at all

Perfectly

Aqueous and vitreous index

1.34

Cornea index

1.376

Water index

1.33

Snells law / refraction of light

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

Fundamental paraxial equation

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

What does the fundamental paraxial equation do

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

What does paraxial stand for

Rays near the axis

Vergence power of a lens formual

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

What does vergence power of a lens equation mean

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

Distance of the object from the lens formula

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

Distance of the image from the lens formula

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

Focal length formula

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

prentices rule p=cF

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

Prentices formula

Prism= F x decentration (mm) / 10

Emmetropia

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

Ametropia

A deviation from emmetropia

Myopia

-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

Hypermetropia

-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

Astigmatism

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

Astigmatic ametropia

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

When astigmatism is measured through an EE what does it mean

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

Can a keratometer measure corneal astigmatism?

yes

With the rule astigmatism

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

Against the rule astigmatism

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

Regular astigmatism

Refractive error is constant over the refracting surface

Irregular astigmatism

Refractice error varies over the refracting surface

Possible causes of irregulr astigmatism

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

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

at least every 10 years

when should a 55 year old diabetic get an EE

at least every 2 years

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

At least every 2 years

when should a healthy 45 year old hispanic get an ee

at least every 3 years

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

at least every 2 years