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PPO 3 > Midterm #2 > Flashcards

Midterm #2 Flashcards

1
Q

what might an esophoria at distance suggest?

A

hyperopia or an over-minused patient

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2
Q

what might an exophoria at near suggest?

A

undercorrected myopia

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3
Q

how do you get a spherical equivalent?

A

take half the cylinder power (keep sign) and add it to sphere power

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4
Q

OD: -0.50 -1.00 x 180

what would the unaided VA be expected to be?

A

20/50 - about -1.00D of blur

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5
Q

what is refractive hyperopia?

A

abnormal refractive power due to curvatures that are too flat (do not have enough power)

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6
Q

what is axial hyperopia?

A

abnormal refractive power due to an axial length that is shorter than normal

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7
Q

what is simple myopia?

A

most common type, no pathology, usually less than 6D, juvenile or adult onset

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8
Q

what is degenerative myopia?

A

degenerative changes in posterior segment, retina is partially stretched away from disc, decreased BVA, myopic conus, and RD and glaucoma are common

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9
Q

what is nocturnal myopia?

A

only occurs in dim illumination, increased accommodative response toward dark focus

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10
Q

what is pseudomyopia?

A

inappropriate accommodative response, overstimulation or spasm

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11
Q

what is induced myopia?

A

occurs with pharmaceutical agents, blood sugar changes, NS - temporary and reversible

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12
Q

what two things change during emmetropization?

A

radii of cornea and lens (refractive) and length of eye (axial)

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13
Q

what refractive power is the end result of emmetropization?

A

emmetropic or slightly hyperopic (acts as visual buffer)

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14
Q

what do minus lenses induce during emmetropization?

A

induce hyperopic defocus - causing the eye to develop myopia

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15
Q

what do plus lenses induce during emmetropization?

A

induce myopic defocus - causing the eye to develop hyperopia

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16
Q

what part of the eye does myopia change in emmetropization?

A

sclera

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17
Q

what part of the eye does hyperopia change in emmetropization?

A

choroid

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18
Q

what are two influential factors for emmetropization?

A

image quality and neuronal interaction

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19
Q

what are the best ways to control myopia?

A

bifocal, multifocal CL’s and orthokertatology

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20
Q

why can’t you control myopia progression with myopic glasses?

A

the higher the lens power, the larger the peripheral defocus - eye grows until periphery is same defocus as center

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21
Q

what is tonic convergence?

A

convergence maintained by the EOM tonus (phoria position)

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22
Q

what is accommodative convergence?

A

occurs reflexively with stimulation of accommodation

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23
Q

what is proximal (psychic) convergence?

A

due to awareness or impression of nearness of an object

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24
Q

what is fusional vergence?

A

typically autonomic response to retinal disparity - when an image falls outside panum’s fusional area

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25
Q

what is positive fusional vergence?

A

both eyes move in or converge

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26
Q

what is negative fusional vergence?

A

both eyes move out or diverge

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27
Q

what is vertical fusional vergence?

A

one eye moves up and the other moves down

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28
Q

what type of vergence is measured using BD prism?

A

supravergence

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29
Q

what do you measure infravergence with?

A

BU prism

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30
Q

what is the AC/A ratio?

A

the relationship between accommodative convergence (lateral phoria) and accommodation (usually 1 diopter)

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31
Q

how do you measure the gradient AC/A?

A

measure near lateral phoria (40cm), add +1.00 sphere, remeasure near lateral phoria = difference between two measurements : 1 diopter

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32
Q

what is Morgan’s expected for AC/A?

A

4/1 (+/- 2)

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33
Q

what is Morgan’s expected for distance lateral phoria?

A

1 exo (+/- 2)

34
Q

what is Morgan’s expected for near lateral phoria?

A

3 exo (+/- 3)

35
Q

what is Morgan’s expected for amplitudes?

A 
ave = 18 - 1/3(age)
min = 15 - 1/4(age)
36
Q

what is Morgan’s expected for FCC?

A

+0.50 (+/- 0.50)

37
Q

what is Morgan’s expected for NRA?

A

+2.00 (+/- 0.50)

38
Q

what is Morgan’s expected for PRA?

A

-2.37 (+/-1.00)

39
Q

how do you calculate the convergence demand?

A

pd (prism diopters) = convergence demand

pd = PD(cm) x meter angle (1/test distance)

40
Q

what are some symptoms of accommodative insufficiency?

A

blurry vision at near, discomfort/strain/fatigue with near work, difficulty with attention and concentration at near

41
Q

what are some clinical signs of accommodative insufficiency?

A

esophoria at near, low accommodative amplitude, low PRA, will accept plus at near (any age)

42
Q

what is the most common non-strabismic binocular condition?

A

convergence insufficiency

43
Q

what are some clinical findings for convergence insufficiency?

A

normal distance lateral phoria and higher exophoria at near (more than 6pd), reduced NPC, low NRA and low AC/A

44
Q

what type of ametropia is best corrected with CL’s?

A

refractive ametropia

45
Q

what type of ametropia is best corrected with spectacles?

A

axial ametropia

46
Q

what can you use to correct for aniseikonia?

A

plano size lenses

47
Q

what plano size lens could you use for 4% aniseikonia?

A

use 4% size lens over one eye to cancel (concave side towards eye to magnify)

48
Q

what is the order of tests in the near testing suite?

A

FCC, NRA, PRA, phorias and vergences

49
Q

what is the FCC testing?

A

evaluates the accommodative posture of a patient while viewing a near target under binocular conditions

50
Q

what does it mean if the FCC is over +0.75 in pre-presbyopes?

A

the patient may be over-minused

51
Q

what does it mean if the FCC is a minus number?

A

the patient has a lead of accommodation - may consider VT

52
Q

what are the NRA and PRA testing?

A

accommodation under binocular conditions when total convergence demand is constant - how changes in accommodative convergence are compensated for by changes in fusional vergence

53
Q

what 3 things happen when looking from distance to near?

A

convergence, accommodation, miosis

54
Q

what are normal K readings?

A

44.00D

55
Q

a patient has -1.75 x 180 astigmatism in the OD, what is the predicted refractive astigmatism (Javal’s rule)?

A

-1.25 x 180

56
Q

a patient has -2.50 x 090 astigmatism in the OD, what is the predicted refractive astigmatism (Javal’s rule)?

A

-3.00 x 090

57
Q

what is compound myopic astigmatism?

A

(CMA) myopic in both meridians

58
Q

what is simple myopic astigmatism?

A

(SMA) myopic in one meridian and emmetropic in other

59
Q

what is mixed astigmatism?

A

(mixed A) myopic in one meridian and hyperopic in other

60
Q

what is compound hyperopic astigmatism?

A

(CHA) hyperopia in both meridians

61
Q

what is simple hyperopic astigmatism?

A

(SHA) hyperopic in one meridian and emmetropic in other

62
Q

what is manifest hyperopia?

A

measured by relaxation of accommodation with addition of plus lenses - detected dry refraction

63
Q

what is latent hyperopia?

A

portion of total hyperopia compensated for by tonicity of ciliary muscle - revealed with wet refraction (wet - dry refraction = latent)

64
Q

what is total hyperopia?

A

manifest + latent hyperopia or total will equal amount revealed with wet refraction

65
Q

what is facultative hyperopia?

A

can be self-corrected with accommodation, uncorrected distance VA may be 20/20

66
Q

what is absolute hyperopia?

A

cannot be overcome with accommodation - uncorrected distance VA will be worse than 20/20

67
Q

what are the average powers for the cornea, lens and total eye power?

A

cornea = 43D
lens = 17D
total eye = 60D

68
Q

what is the average axial length?

A

24mm

69
Q

what are some symptoms of uncorrected astigmatism?

A

blur at distance and near, “ghost” images/diplopia, bothered by bright lights/glare, asthenopia, tearing

70
Q

how can you check if your patient has true diplopia or astigmatism symptoms?

A

have the patient close one eye if the diplopia is still there monocular = lens/astigmastim (binocular = nerve palsy, stroke, DM changes)

71
Q

why does the binocular balance work?

A

accommodation is consensual; the patient’s accommodative responses of the eyes is always matched

72
Q

what test answers the questions: where are the eyes focused when fixating a stationary near target? Is there a lag or lead of accommodation?

A

Fused Cross Cylinder Test (FCC)

73
Q

what is an accommodative demand and how do you calculate it?

A

distance of blurred target in diopters - 40cm = (100/40) = 2.50D

74
Q

if a target at 40 cm has an accommodative demand of 2.50D, but the patient accommodates 2.00D, do they have lead or lag?

A

lag of accommodation

75
Q

what is the most important cue to accommodation?

A

blur or defocus (accommodative stimulus)

76
Q

how much lag at near is normal?

A

+0.25 to +0.50 and increases with age

77
Q

what type of convergence is active during the distance lateral phoria measurement?

A

tonic convergence

78
Q

what types of convergence are involved when measuring the near lateral phoria?

A

tonic, accommodative and proximal convergences

79
Q

which test do the eyes move instead of the image, phorias or vergences?

A

vergence (image moves in phorias)

80
Q

what 3 things must the patient have in order to do the binocular balance?

A
  1. vision is same in each eye
  2. has accommodation
  3. good enough VA’s to notice small discrepancies in refraction

PPO 3 (1 decks)

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