Refractive Errors

Question 1

What is Myopia?

Answer 1

• The eyeball is too long, or the cornea is too curved
• Light rays are focused in front of the retina
• Near objects are clear

Question 2

What is Hyperopia?

Answer 2

• The eyeball is too short or the cornea is too flat,
• Light rays are focused behind the retina
• Far objects are clear

Question 3

What is Astigmatism?

Answer 3

• Light rays don’t come to a single focus but instead, focus on more than one spot

Question 4

As we age what happens to the lens?

Answer 4

Lens becomes less flexible which can lead to hyperopia because the lends struggles to focus on nearby objects

Question 5

What contributes to developing myopia in the vision?

Answer 5

• Prolonged screen time
• reading without proper lighting
• not enough time outdoors

Question 6

What type of lens helps with myopia(minus) sight?

Answer 6

Concave lens (thinner in the center)

Question 7

What type of lens helps with hyperopia(plus) sight?

Answer 7

Convex lenses (thicker in the center) .

Question 8

What type of lens helps with astigmatism?

Answer 8

Cylindrical lenses are used to correct the irregular curvature of the cornea

Question 9

What does OD stand for and what does it refer to?

Answer 9

Oculus Dexter: Refers to the right eye

Question 10

What does OS stand for and what does it refer to?

Answer 10

Oculus spinster: left eye

Question 11

What does SPH stand for and what does it do?

Answer 11

Sphere: indicates the degree of myopia or hyperopia

Question 12

What does ClY stand for and what does it do?

Answer 12

Cylinder: indicates degree of Astigmatism

Question 13

What does the axis do?

Answer 13

Ensures that the cylindrical correction to address the specific shape of the eye

Question 14

What does the ADD do for the spectacle prescription?

Answer 14

ADD is to additional magnifying power for reading (used for presbyopia)

Question 15

Explain what this prescription is trying to say.
OD: -2.00 sph, -1.00 cyl, 180 degree axis
OS: -1.50 sph, -0.50 cyl, 90 degree axis

Answer 15

The OD (right eye) needs a concave lends of -2.00 diopter for myopia while the -1.00 diopter cylindrical correction for astigmatism with the cylindrical axis at 180 degrees.
The OS (left eye) needs a concave lens of -1.50 diopters of myopia while the -0.50 diopter cylindrical correction for astigmatism at 90 degrees

Question 16

what is myopia corrected with?

Answer 16

Minus lenses

Question 17

What is hyperopia corrected with?

Answer 17

Plus lenses

Question 18

What is the primary purpose of the eye?

Answer 18

To focus light on the retina.

Question 19

What are the steps of how vision works.

Answer 19

1. Light enters the eye through the cornea.
2. Travels through the clear aqueous fluid and passes through the pupil
3. As muscles in the iris relax or constrict, the pupil changes size to adjust the amount of light entering the eye
4. Light rays are then focused through the crystalline lens.
5. Proceed through the vitreous
6. Then reaches the retina where the light rays are converted into an electrical impulse that travels along the optic nerve to the brain where it is interpreted as an image

Question 20

What is emmetropia?

Answer 20

• Normal 20/20 vision
• The eye focuses light perfectly onto the retina without the need for corrective lenses.

Question 21

What is another name for Nearsightedness?

Answer 21

• Myopia
• Objects near are clear but distant objects are unclear

Question 22

What is another name for Farsightedness?

Answer 22

• Hyperopia
• Objects near are blurry and distance objects are clear

Question 23

What is compound myopic Astigmatism?

Answer 23

• Both focal points are in front of the retina but in two different location.

Question 24

What is compound hyperopic astigmatism?

Answer 24

• Both focal point are behind the retina in two different location.

Question 25

What is mixed astigmatism?

Answer 25

- One focal point is in front of the retina, while the other is behind.

Question 26

What is presbyopia?

Answer 26

- When the crystalline lens is no longer able to change shape which prevents light to focus on the retina for near objects.

Question 27

What corrects presbyopia?

Answer 27

- Bifocal or multifocal lenses

Question 28

Approximately how much power can be generated by the eye's optical system?

Answer 28

- 60 diopters

Question 29

What is simple myopic Astigmatism?

Answer 29

- One focal point is on the retina while the other focal point is in front of the retina

Question 30

What is simple hyperopic Astigmatism?

Answer 30

- When one focal point is on the retina while the other is behind the retina

Question 31

Is the problem below simple myopic astigmatism or simple hyperopia astigmatism? -2.00 +2.00 x 40

Answer 31

Simple myopic astigmatism

Question 32

Is the problem below simple myopic astigmatism or simple hyperopia astigmatism? -0.50 + 0.50x135

Answer 32

Simple Myopic Astigmatism

Question 33

Is the problem below compound myopic astigmatism or Compound hyperopia astigmatism? -1.50 +0.50x135

Answer 33

compound myopic astigmatism

Question 34

Is the problem below compound myopic astigmatism or Compound hyperopia astigmatism? +2.50 -2.00 X 130

Answer 34

Compound hyperopia astigmatism

Question 35

Is the problem below compound myopic astigmatism or Compound hyperopia astigmatism? +0.50 +0.50 X 135

Answer 35

Compound Hyperopia Astigmatism

Question 36

Is the problem below compound myopic astigmatism or Compound hyperopia astigmatism? -4.50 + 2.00 X 45

Answer 36

Compound Myopic Astigmatism

Question 37

What type of Astigmatism is this? -1.00 +2.00 X 135

Answer 37

Mixed Astigmatism

Question 38

What ocular structure does light interact with first when light enters the eye?

Answer 38

Cornea

Question 39

When the light enters the eye through the cornea, it travels through what?

Answer 39

It travels through the clear aqueous fluid and passes through the pupil

Question 40

What will the eye do to allow a certain amount of light to enter the eye?

Answer 40

As muscles in the iris relax or constrict, the pupil changes size to adjust the amount of light entering the eye.

Question 41

Where do light rays pass next after the cornea and pupil?

Answer 41

Light rays are then focused through the crystalline lens and proceed through the vitreous

Question 42

Where do light rays pass next after the crystalline lens and vitreous?

Answer 42

Light rays then reach the retina.

Question 43

What does the retina do to the light rays?

Answer 43

Converts the light rays into electrical impulse that travels along the optic nerve to the brain, where it is interpreted as an image.

Question 44

What does 20/20 vision mean?

Answer 44

When a person can see an object at 20 feet, that normally sighted person can also see it at 20 feet.

Question 45

What does 20/40 vision mean?

Answer 45

When a person can see an object at 20 feet, that normally sighted person can see 40 feet.

Question 46

How is the power generated for the eye?

Answer 46

Power is generated by the cornea and the crystalline lens.

Question 47

If light isn't bent properly, what happens to the image?

Answer 47

The image doesn't focus on the retina, and there is a refractive error.

Question 48

What do Concave lens and convex lens help with?

Answer 48

Diverge light rays, allowing them to focus on the retina

Question 49

How to tell when patients has simple myopia or hyperopic astigmatisms?

Answer 49

Simple myopic astigmatism prescription will have a negative sphere and a positive cylinder (e.g., -2.00 -1.00 x 180), while a simple hyperopic astigmatism will have a positive sphere and a negative cylinder (e.g., +2.00 -1.00 x 180)