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o and m > management of ic deviations > Flashcards

management of ic deviations Flashcards

1
Q

what do you need to know from the investigation

A

weather it is a paresis or paralysis

the level of incomitance i.e weather muscle sequelae has developed or not

differential diagnosis - is it acquired or congenital

is it recent or longstanding

the symptoms ie.e ptosis , pain , diplopia decrease in vision , nystagmus or other

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2
Q

what do you need to know about diplopia

A

is it constant or intermittent

what direction i.e. horizontal or vertical or torsional

where is the largest separation of images, i.,e. what positions of gaze , near distance or both fixation distances

are they able to relieve diplopia by closing one eye and which eye do they prefer to close

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3
Q

what do you need to know about the symptoms- regarding pain

A

do they have pain - when and what positons of gaze

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4
Q

what do you need to know regarding colour vision/ visual loss

A

do they have reduced colour vision

do they have reduced contrast sensitivity

do they have visual field defects

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5
Q

what do you need to know regarding ptosis

A

is it complete/partial

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6
Q

what do you need to know regarding nystagmus

A

type and direction

constant / intermittent

ocscillipsia

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7
Q

what are the aims of orthoptic management

A

observation - allow time for spontaneous recovery before considering surgery

9-12 months and ocular motility stable for at least 3 months

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8
Q

what do you need to do during the observation period

A

monitor improvement / deterioration

offer conservative management

make patient comfortable

restore potential bsv

obtain good ocular alignment if no bsv potential

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9
Q

what are methods of relieving / minimising diplopia

A

teach ahp , prisms , occlusion

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10
Q

what do you need to know about ahp

A

aim is to move eyes away from the field of parsed muscle

and move eyes to a position where the deviation is the least
type depends on direction of muscle

and position of gaze where they appreciate diplopia

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11
Q

what are the types of ahp

A

head turn

head tilt

chin elevation head up

chin depression head down

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12
Q

what would the typical ahp in a patient with a left 6th nerve palsy and diplopia to the left be

A
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13
Q

what are the aims of prism

A

restore bsv - use smallest prisms which restore comfortable bsv

move image into supression area if potential bsv is absent

separate images further if no potential bsv or suppression area

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14
Q

what do the type of prisms depend on

A

direction of diplopia

constant/ intermittent diplopia

distances diplopia is appreciated at

positions of gaze where diplopia is appreciated

duration and stability of deviation

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15
Q

what types of prisms are their

A

temporal - fresnel prisms

permeant - incorporated prisms

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16
Q

what types of fit can you have for prisms

A

full lenses

distance or reading glasses only

upper segment or bifocal segment

split prisms

17
Q

what are the disadvantages of prisms

A

optical distortion

horizontal magnification

vertical magnification

curvture or vertical lines (less so in prisms incooportated into glasses

asymmetric horizontal magnificztion

change in vertical
magnification with horizontal angles

18
Q

How do fresnel prisms affect chromatic dispersion and dynamic va

A

cd= fresnel prisms cause diffraction of light by the grooves In the fresnel prisms

reduces contrast

effects visual acuity , contrast sensitivity and steroacuity
and this reduction is substantial if the prism is more than 10 diopters

if incorporated into glasses it reduces va to 6/9

fresnel prisms reduce va to 6/12

dva - ability to discriminate an object when their is movement between the object and individual

DVA is increasingly reduced as fresnel prism strength increased
Identification of orientation of a moving Landolt C viewed at 57cm (Maconachie et al. 2010)

19
Q

how is va effected with fresnel prisms

A

va reduces with increasing prism power

progressive reduction in va under photopic (day light) and Mesopic (night) conditions - participants were dark adapted for 5 mins

in photooptic conditions using over 15 diopter prism participants should not be driving

in Mesopic conditions using under 5 diopters participants should not be driving

20
Q

what are the advantages of fresnel prisms

A

orientation of prism has no effect on va and contrast sensitivity

lightweight

easily changeable

may relieve ahp

may allow return to work and ability to do daily tasks

21
Q

what are the indications for prism incoorporation

A

stable angle of deviation (after observation period)

comfortable in prisms - reasonably concomitant

power of prism relatively small

surgery contraindicated

problems - weight , edge thickness

22
Q

when would you choose a fresnel prism rather than incorporating the prism into the patients glasses

A
23
Q

how successful is the use of prisms

A

4th nerve palsy

prisms useful is relatively small vertical deviation in pp and fairly concomitant

full correction of angle often required to relieve diplopia

eexpeection - longstanding with extended vertical fusion range

6th nerve palsy

prisms useful is minimal/ small amount of lateral incomintance

typical prism prescribed for horizontal deviations is generally 50% of the total deviation

successful use of prisms more likely if realistic patient expectations , frequent follow up and patient is under 65 years

24
Q

how successful is the use of prisms

A

Hatt et al (2014) performed a retrospective study including 34 patients (aged 14-84 years) with diplopia
Aim: determine if successful treatment of diplopia improve HRQOL
Method: two questionnaires pre-prism treatment and at follow up
Diplopia questionnaire: rate severity of diplopia (5-point scale)
Adult strabismus questionnaire: four areas
Self-perception
Reading
Interactions
General function

74% were prescribed Fresnel prism and 26% had prisms incorporated

Conclusion: successful correction of diplopia with prisms improve functional domains but psychosocial domains unchanged

25
Q

how do you work out the true angle of deviation for a 4th nerve palsie for a longstanding unilateral 4th nerve

A

prism adaptation

fully correct angle of deviation with prisms for 1-2 weeks

perform pct on return to determine if angle has increased

diagnostic occlusion

occlude the paretic eye (non fixing eye) for 1 day- 2 weeks ft

perform pct before occlusion and on return without allowing binocular vision

26
Q

what are the options for occlusion and what does it depend on

A

options for occlusion are

blenderm

bangrter foils

frosted lenses

occlusive contact lenses

type depends on

constant/ intermittent diplopia

position of gaze appreciate diplopia

duration and stability of deviation

27
Q

which type of occlusion would you choose in a recent onset case with trouble some diplopia that cannot be relieved by prisms

A
28
Q

what are the types of fits of occlusion

A

total occlusion

lower or upper segment occlusion

sector occlusion

29
Q

what happens after the observation period

A

you look for outcome

recovery , stability , detoeritaion

management options - conservative management - continue use of small ahp , fresnel prism and occlusion

incorporate prisms , frosted lens , occlusive contact lens

botulinum toxin a

surgery

post botulinum toxin post surgery

ahp, prism and or occlusion for residual symptoms

30
Q

what factors affect management

A

general , age , ateiology , general health, occupation

ocular- severity of symptoms, duration since onset , presence and size of ahp, binocular functions , torsion , appearance

31
Q

what are the orthoptic management options

A

teach ahp

prisms

occlusion

consider advantages and treatments for each option , factors affecting management , most appreciate treatment option if patient shows recovery , stability , deteoriations

o and m (30 decks)

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