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ABO EXAM OPTICIAN WORKS > Course 1 > Flashcards

Course 1 Flashcards

1
Q

What do Rods and Cones do?

A

The rods and cones send the light as nerve impulses to the brain for interpretation.

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2
Q

emmetropia

A

Is an eye with perfect vision. The rays of light entering the eye focus on the retina right where they need to be. No need for corrective lenses.

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3
Q

What is Refraction?

A

Refraction is the bending of light that occurs in a lens.

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4
Q

What is a refractive error?

A

When an individual suffers from wandering rays of light. Aka the light doesn’t come to focus on the Fovea.

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5
Q

What is simple myopia?
Is it nearsightedness or farsightedness?
How is this corrected?
What is the shape of the eye or cornea?

A
  • the point of focus falls in front of the retina.
  • nearsightedness
  • with a minus rx. (think my-opia, mi-nus lens)
  • the eye is long or the cornea is too steeply curved.
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6
Q

What is simple hyperopia?
Is it nearsightedness or farsightedness?
How is this corrected?
What is the shape of the eye or cornea?

A
  • the point of focus falls behind the retina.
  • farsightedness
  • with a plus rx.
  • the eye is short or the cornea is too shallowly curved.
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7
Q

What is simple myopic astigmatism?
What is the shape of the eye or cornea?
How is this corrected and what is an example?

A
  • SOME of the rays of light fall short of the retina.
  • The cornea is not perfectly round, but instead has two different curves.
  • ONE focus point of the RX will provide no correction, another focus point of the RX will have minus power.
  • Example: 0.00 -0.50 X 45
    - 0.50 + 0.50 X 135 (transposed=zero cyl)
    0. 00 -2.00 X 130
    - 2.00 +2.00 X 40 (transposed=zero cyl)
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8
Q

Eyes with simple myopic/hyperopic astigmatism is corrected with what kind of lens?

A

It is corrected using lenses with variable powers. Also known as sphero-cylinder lenses, toric lenses, or sometimes compound lenses.

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9
Q

What is simple hyperopic astigmatism?
What is the shape of the eye or Cornea?
How is this corrected and what is an example?

A

-SOME of the rays of light focus behind the retina.
-The cornea is not perfectly round, but instead has two different curves.
-ONE focus point of the RX will provide no correction, another focus point of the RX will have plus power.
-Example: +1.50 -1.50 X 45 (transposed=zero cyl)
0.00 +1.50 X135
+2.50 -2.50 X 130 (transposed=zero cyl)
0.00 +2.50 X 40

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10
Q

What is compound myopic astigmastism?
What is the shape of the eye or cornea?
How is this corrected and what is an example?

A
  • ALL the rays of light fall short of the retina.
  • The cornea is not perfectly round, but instead has two different curves.
  • All lens have minus power in all areas of the lens/RX.
  • Example: -1.00 -0.50 X 45
    - 1.50 +0.50 X 135
    - 2.50 -2.00 X 130
    - 4.50 + 2.00 X 40
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11
Q

What is a compound hyperopic astigmatism?
What is the shape of the the eye or cornea?
How is this corrected and what is an example?

A

-ALL the rays of light focus behind the retina.
-The cornea is not perfectly round, but instead has two different curves.
-All these examples have plus power in all areas of the lens/RX.
-Examples: +1.00 -0.50 X 45
+0.50 +0.50 X 135
+2.50 -2.00 X 130
+0.50 +2.00 X 40

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12
Q

What is mixed astigmatism?
Is it nearsightedness or farsightedness?
What is the shape of the the eye or cornea?
How is this corrected and what is an example?

A
  • some rays of light focus ahead of the retina, some focus behind the retina.
    -the cornea is misshapen.
  • one area of the RX has minus power while another part of the RX has plus power.
    -Examples: +1.00 -2.00 X 45
    -1.00 +2.00 X 135
    +2.00 -2.25 X 67
    -0.25 + 2.25 X 157
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13
Q

What is Presbyopia?

How is this corrected and what is an example?

A

-it is a refractive condition in which you are unable to accommodate (read fine print, thread a needle, or do fine work) without magnification.
-with an add power.
-Examples: Add +1.25
Add +2.50

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14
Q

What is Accommodation?

A

-The increase in plus power by changing the shape of the crystalline lens by relaxing the ciliary muscle.

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15
Q

What are the two equations to find the value of a diopter?

What do the components stand for?

A
  • D=1/f and F=1/D
  • D=diopters
    f=focal length
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16
Q

A prism of 1.00 diopter produces the appearance of what?

A

-it produces a 1 centimeter shift in position of an object being viewed at a distance of 1 meter.

17
Q

What produces a 1 centimeter shift in position of an object being viewed at a distance of 1 meter.

A

-a prism of 1.00 diopter.

18
Q 
What is The Nominal Lens Formula?
What do the components stand for?
What is it called when a cylinder is added to the equation?
What is it used for?
What is the flaw and why?
A
  • DL=D1+D2
  • DL=total power of the lens
  • D1=the front surface power
  • D2=the back surface power
  • Toric Transpostion
  • To calculate the total power of a lens.
  • It does not calculate the total power of the lens accurately because the formula does not take into the account of lens thickness and the index of refraction.
19
Q

What is the back vertex depth formula?
What do the components stand for?
What is it used for?

A
  • power=back+ front/1-(tm/n)front
    (power=back+front over 1-(tm over n) front.
  • back=back curve
  • front=front curve
    -tm=thickness of lens (calculate to meters)
    -n=index of refraction.
  • to calculate the total power of the lens.
20
Q

What is a phoropter?

A

-The instrument used by doctors to determine the patient prescription.

21
Q

What does “n” stand for?

A

Index of refraction

22
Q

Index of refraction is a numerical representation of what?

A

-how much a material will slow the speed of light when it is traveling through it.

23
Q

A material with a higher index of refraction will do what to light?

A

slow it down.

24
Q

What is the Index of refraction for a High Index lens?

A

1.67

25
Q

What is the Index of refraction for a CR-39 lens?

A

1.498

ABO EXAM OPTICIAN WORKS (1 decks)

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