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OT > NV Syndromes, Prescribing Prism > Flashcards

NV Syndromes, Prescribing Prism Flashcards

1
Q

What is convergence insuffiency at Distance and Near?

A

Distance: Ortho
Near: Exophoria

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2
Q

What is divergence insuffiency at Distance and Near?

A

Distance: Esophoria
Near: Ortho

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3
Q

What is convergence excess at Distance and Near?

A

Distance: Ortho
Near: Esophoric

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4
Q

What is divergence excess at Distance and Near?

A

Distance: Exophoric
Near: Ortho

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5
Q

Overall, what is convergence insuffiency or excess lead to at distance?

A

ORTHO

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6
Q

Overall, what is divergence insuffiency or excess lead to at near?

A

ORTHO

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7
Q

If the patient is 4XP at distance and 12XP at near can they still be considered convergence insuffient?

A

Yes

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8
Q

What are the biological causes for divergence insuffiency?

A

Anotomical:
Low muscle tone
Abnormal orbital shape
Abnormal orbital position
Abnormal Check ligaments
Abnormal muscle insertions

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9
Q

What is the way to fix divergence insuffiency? What would this lead to?

A
  1. Correct Rx
  2. Train divergence
  3. VT for vergence
  4. Rarely prism

ESOPHORIA

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10
Q

What causes convergence insuffiency?

What do these pt show clinically?

A

Under accommodation from:

  1. Uncorrected myopia
  2. Absolute Hyperopia
  3. Suppression
  4. Monocular Viewing
  5. Presbyopia
  6. Large PD

Reduced PRV and receded NPC

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11
Q

Should convergence insuffiency take off glasses to read?

A

No because large PD and exo at near

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12
Q

How do you manage convergence insuffiency?

A
  1. Correct Rx
  2. Train accommodation with flippers
  3. Train vergence with flippers, vectograms or brock string
  4. Rarely prism
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13
Q

What are the cause of convergence excess?

A

Excess accommodation due to uncorrected hyperopia (latent hyperopia), accommodative spasm, pseudomyopa or early presbyopia.

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14
Q

What do convergence excess pt display?

A

Reduced BI, and large lag of accommodation

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15
Q

How do you manage convergence excess?

A
  1. Correct Rx
  2. Use bifocals with high AC/A NOT low AC/A
  3. Train divergence at near
  4. Increase Working distance or decrease duration of near work
  5. Rarely prism
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16
Q

What are the causes of divergence excess?

A

Basic Exo (Exo at distance and near) with high AC/A
Anotomical factors
With age becomes more Exo

17
Q

How do you manage divergence excess?

A

Difficult to do but can train accurate vergence at distance
Rx 2 glasses one with prism for distance and one without for near

18
Q

When would a pt with divergence excess become symptomatic?

A

As they get older because they had a larger amplitude of accommodation when they were younger thus they could compensate

19
Q

Based on EBM VT is only good for which problem?

A

Convergence insuffiency
(Ortho at distance and exo at near)

20
Q

How does brock string work?

A

Point of fixation is single while everything else is seen in diplopia

21
Q

What happens if the pt is an over converger and perform brock string?

A

They will converge the two strings together in the front and see bead as double

22
Q

What happens if the pt is an under converger and perform brock string?

A

They will converge strings behind the bead and the bead will appear double

23
Q

What evaluation does brock string give us?

A

Fixation Disparity

24
Q

What is the overall goal of brock string?

A

To make the “two strings” cross at the fixation bead

25
Q

Prescribing too much horizontal prism is good for which type of pt?

A

Vertical deviations

26
Q

What are morgan’s norms?

How is it used to Rx?

A

Distance: 0-2XP
Near: 0-6XP

Was never meant to Rx but you would add prism until the pt is in normal range

27
Q

What is percival criterion best for?

What does it not consider?

A

Best for ESO
Does not consider size of phoria

28
Q

What is Rx’ing with fixation disparity good for?

A

Rx with associated phoria this shows the uncompensated phoria and is good for horizontal deviations

29
Q

What do prisms do to the FD curve?

A

Shift left and right

30
Q

What does plus and minus lenses do to the FD curve?

A

Shift it up or down

31
Q

What does VT do to the FD curve?

A

VT flattens the curve

32
Q

When should plus lenses be used over prisms?

A

High AC/A
Eso because they are hyperopic
Lead of accommodation
Low Amp of accommodation

33
Q

In which situation is ground prism better? PD= 65

Ie: 2prisms

A

When the Rx is lower ie: +1.00

Because if the pt needed 2prisms and you ordered prism by decentration then it would be
p=cF

2=c(1)
c=20mm/ eye which would be a DBC of 65-40= 25= Crazy

34
Q

What is prism titration?

A

When you introduce prism till the pt reports the previous higher prism was better

35
Q

What does VT improve?

A

The SFV system by improving prism adaption

36
Q

What is asthenopia?

A

Eye fatigue from demand on FFV system

OT (13 decks)

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