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Strabismus > Orthoptic management of incomitant deviations > Flashcards

Orthoptic management of incomitant deviations Flashcards

1
Q

What do you need to know about diplopia?

A

Constant/ intermittent
Direction
Largest separation of images
Is diplopia relieved after closing one eye

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2
Q

What are the directions of diplopia

A

Horizontal
Vertical
Torsional

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3
Q

Where can images separate

A

Which position of gaze
N, D or both

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4
Q

What to consider if one eye is closed to relieve diplopia

A

Which eye prefers to close

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5
Q

Pain

A

When and which positions of gaze

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6
Q

Reduced vision/ visual loss

A

colour vision
contrast sensitivity
visual field defect

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7
Q

Ptosis

A

complete or partial

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8
Q

Nystagmus

A

type and direction
constant/ intermittent
oscillopsia

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9
Q

Aims of orthoptic management

A

Observation
Allow time for spontaneous recovery before consider surgery
9-12 months and ocular motility stable for at least 3 months

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10
Q

During observation period…

A

Monitor any improvement/ deterioration
Offer conservative management
Make patient comfortable
Restore potential BSV
Obtain good ocular alignment if no BSV potential

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11
Q

Methods of relieving diplopia

A

teach AHP
prisms
occlusion

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12
Q

Adopting AHP -type depends on

A

Direction of diplopia
Position(s) of gaze appreciate diplopia

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13
Q

Aim of AHP

A

moving eyes away from field of action of paresed muscle and into a position where the deviation is least

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14
Q

Type of AHP

A

Head turn
Head tilt
Chin elevation (Head up)
Chin depression (Head down)

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15
Q

What would be the typical AHP in a patient with a left 6th nerve palsy and diplopia to the left?

A

Left

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16
Q

Aim of using prisms

A

Restore BSV
Use smallest prisms which restore comfortable BSV
Move image into suppression area if potential BSV absent
Separate images further if no potential BSV or suppression area

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17
Q

Type of prism depends on

A

Direction of diplopia
Constant/ intermittent diplopia
Distance(s) appreciate diplopia
Position(s) of gaze appreciate diplopia
Duration and stability of deviation

18
Q

Prism options

A

Temporary – Fresnel prisms
Permanent – incorporate prisms

19
Q

Fit of prisms

A

Full lens
Distance or reading glasses only
Upper segment or bifocal segment
Split prisms

20
Q

Fresnel prism disadvantages

A
  • Optical Distortion
    Horizontal magnification
    Vertical magnification
    Curvature of vertical lines (less so in prisms incorporated into glasses)
    Asymmetric horizontal magnification
    Change in vertical magnification with horizontal angle
    -Chromatic dispersion
    Diffraction of light by grooves in Fresnel prism
    Cause reduced contrast
    Effect VA, contrast sensitivity, fusion and stereoacuity
    Reduction substantial if prism >10∆
    10∆ prism (Kulnig, 1987)
    Incorporated into glasses: reduce VA to 6/9 (~0.15 logMAR)
    Fresnel prisms: reduce VA to 6/12 (0.30 logMAR)
    -Dynamic visual acuity (DVA)
    The ability to discriminate an object when there is movement between 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)
21
Q

With increasing prism power

A

visual acuity reduces

22
Q

Fresnel prisms advantages

A

Orientation of prism has no effect on VA and contrast sensitivity (Veronneau-Troutman, 1978)
Lightweight
Easily changeable
May relieve AHP
May allow return to work & ability to do daily tasks

23
Q

What to consider when fitting a prism

A

Which eye?
The amount of deviation needs correcting
Orientation of prism if both horizontal and vertical deviation present

24
Q

Fitting prisms

A

Fit
Draw outline slightly smaller than edge of lens using non-permanent marker pen
Place under water
Apply prism to back surface of lens
If very high curvature (high myopic correction) apply to front surface
Remove air bubbles by wiping/pressing in apex to base direction

25
Q

Incorporation of prisms

A

Indication
Stable angle of deviation (after observation period)
Comfortable in prisms
Reasonably concomitant
Power of prism relatively small (<8 PD either eye)
Surgery contraindicated
Problems
Weight
Edge thickness

26
Q

When would you choose a Fresnel prism rather than incorporating the prism into the patient’s glasses?

A

when prism dioptre is small and a temporary problem

27
Q

Success of prisms in fourth nerve palsy

A

Prisms useful if relatively small vertical deviation in P.P. and fairly concomitant
Full correction of angle often required to relieve diplopia
Exception: longstanding with extended vertical fusion range

28
Q

Success of prisms in sixth nerve palsy

A

Prisms useful if minimal/small amount of lateral incomitance
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 >65 years
(Gunton and Brown, 2012)

29
Q

How successful is use of prisms - study

A

Diplopia impacts on patients’ health related quality of life (HRQOL)

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

30
Q

How successful is the use of prisms? study

A

Results: 23 of 34 were successfully treated with prisms
74% were prescribed Fresnel prism and 26% had prisms incorporated
Significant improvement in
Diplopia questionnaire
Adult strabismus 20 questionnaire
Improvement in general and reading function
Unchanged for self-perception and interactions

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

31
Q

Aim of prism adaptation/ diagnostic occlusion 4th nerve palsy

A

determine the true angle of deviation
Advocated for longstanding unilateral SO palsy

32
Q

Method of prism adaptation

A

Fully correct angle of deviation with prisms for 1-2 weeks
Perform PCT on return to determine if angle has increased

33
Q

Method of diagnostic occlusion

A

Occlude the paretic eye (non-fixing eye) for 1 day - 2 weeks FT.
Perform PCT before occlusion and on return without allowing binocular vision

34
Q

Type of occlusion depends on

A

Constant/ intermittent diplopia
Position(s) of gaze appreciate diplopia
Duration and stability of deviation

35
Q

Options of occlusion

A

Blenderm
Bangerter foils
Frosted lens
Occlusive contact lens

36
Q

Which type of occlusion would you choose in a recent onset case with troublesome diplopia that cannot be relieved by prisms?

A
37
Q

Fitting of occlusion

A

Total occlusion
Lower or upper segment occlusion
Sector occlusion

38
Q

After observation - outcome management, post BT and surgery

A

Outcome- Recovery, stability,, deterioration

Management- Conservative management, continue use of small AHP, Fresnel prism and occlusion, incorporate prism, frosted lens, occlusive contact lens, BT, surgery

Post BT/ surgery- AHP, prism and/or occlusion for residual symptoms

39
Q

Factors affecting management

A

-General
Age
Aetiology
General Health
Occupation

-Ocular
Severity of symptoms
Duration since onset
Presence and size of AHP
Binocular functions
Torsion
Appearance

40
Q

Orthoptic management options for incomitant deviations

A

Teach AHP, prisms, occlusion

41
Q

Consider

A

-Advantages/disadvantages for each treatment option
-Factors affecting management
-Most appropriate treatment option if patient shows:
Recovery, stability or deteriorations

42
Q
A

Strabismus (46 decks)

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