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Ophthalmology > 3: Refractive Errors > Flashcards

3: Refractive Errors Flashcards

1
Q

What is a refractive error

A

Failure of the eye to focus light from objects onto the retina to obtain a clear image

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2
Q

What is a refractive error

A

Failure of the eye to focus light from objects onto the retina to obtain a clear image

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3
Q

Why do refractive errors occur

A

Defect in size or shape of the eye

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4
Q

What is ametropia

A

refractive error on looking at distant objects

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5
Q

What is myopia

A

short-sightedness. Image is brought to focus in-front of the retina

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6
Q

What is hypermetropia

A

long-sightedness: image is brought to focus behind the retina

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7
Q

What is astigmatism

A

optical powers are unequal across different meridians

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8
Q

What is presbyopia

A

eye focus range is reduced with age

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9
Q

What is emmetropia

A

no refractive error when looking at distant objects

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10
Q

what is myopia

A

short-sightedness

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11
Q

pathophysiologically what happens in myopia

A

light refracts before the retina

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12
Q

what causes myopia

A
  • Refractive power of the lens is too strong

- AP diameter of the eye is too large

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13
Q

what Is index myopia

A

Refractive power of the lens is too strong

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14
Q

how will individual in short-sightedness present clinically

A

Viewing far away objects is impaired, but close objects is normal.

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15
Q

what is first-line for myopia

A

Corrective lenses

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16
Q

what corrective lens is used for myopia and why

A

Negative lenses as they cause diffraction of the light before the eye refracts it. Meaning light converges on the retina instead of in-front of it

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17
Q

what surgical procedure may be used for myopia

A

LASIK (Laser assisted in situ keratomileusis)

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18
Q

what does myopia increase the risk of

A

Open-angle glaucoma
Retinal detachment
Vitreous detachment

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19
Q

what is hypermetropia

A

long-sightedness

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20
Q

what causes hypermetropia

A

weak lens

short AP diameter

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21
Q

Explain pathophysiology of hypermetropia

A

Light converges behind the retina. To compensate the ciliary muscles contract to try and increase thickness of the lens. This leads to squint in children and tiredness of gaze (headaches, ocular fatigue)

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22
Q

What is first line for hypermetropia

A

Corrective lenses

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23
Q

What type of corrective lenses are used in hypermetropia and why

A

Positive - to increase convergence so they converge before retina

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24
Q

What is second-line for hypermetropia

A

LASIK

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25
What does hypermetropia increase risk of
close-angle glaucoma
26
What is astigmatism
Refracting power of the eye differs between meridians
27
How will astigmatism present
Blurry vision regardless of depth
28
When does astigmatism occur
Cornea does not have the same degree of curvature in each eye. Meaning when light rays are focused they do not come together in the same point.
29
If a regular astigmatism what lenses are required
Cylindrical
30
what is a risk of early-onset astigmatism
amblyopia
31
what is presbyopia
with age tension in ciliary muscles decreases causing lens to become more convex for close focusing
32
how does presbyopia present
difficultly with focusing
33
Why do refractive errors occur
Defect in size or shape of the eye
34
What is ametropia
refractive error on looking at distant objects
35
What is myopia
short-sightedness. Image is brought to focus in-front of the retina
36
What is hypermetropia
long-sightedness: image is brought to focus behind the retina
37
What is astigmatism
optical powers are unequal across different meridians
38
What is presbyopia
eye focus range is reduced with age
39
What is emmetropia
no refractive error when looking at distant objects
40
what is myopia
short-sightedness
41
pathophysiologically what happens in myopia
light refracts before the retina
42
what causes myopia
- Refractive power of the lens is too strong | - AP diameter of the eye is too large
43
what Is index myopia
Refractive power of the lens is too strong
44
how will individual in short-sightedness present clinically
Viewing far away objects is impaired, but close objects is normal.
45
what is first-line for myopia
Corrective lenses
46
what corrective lens is used for myopia and why
Negative lenses as they cause diffraction of the light before the eye refracts it. Meaning light converges on the retina instead of in-front of it
47
what surgical procedure may be used for myopia
LASIK (Laser assisted in situ keratomileusis)
48
what does myopia increase the risk of
Open-angle glaucoma Retinal detachment Vitreous detachment
49
what is hypermetropia
long-sightedness
50
what causes hypermetropia
weak lens | short AP diameter
51
Explain pathophysiology of hypermetropia
Light converges behind the retina. To compensate the ciliary muscles contract to try and increase thickness of the lens. This leads to squint in children and tiredness of gaze (headaches, ocular fatigue)
52
What is first line for hypermetropia
Corrective lenses
53
What type of corrective lenses are used in hypermetropia and why
Positive - to increase convergence so they converge before retina
54
What is second-line for hypermetropia
LASIK
55
What does hypermetropia increase risk of
close-angle glaucoma
56
What is astigmatism
Refracting power of the eye differs between meridians
57
How will astigmatism present
Blurry vision regardless of depth
58
When does astigmatism occur
Cornea does not have the same degree of curvature in each eye. Meaning when light rays are focused they do not come together in the same point.
59
If a regular astigmatism what lenses are required
Cylindrical
60
what is a risk of early-onset astigmatism
amblyopia
61
what is presbyopia
with age tension in ciliary muscles decreases causing lens to become more convex for close focusing
62
how does presbyopia present
difficultly with focusing

Ophthalmology (12 decks)

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