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Strabismus > Accommodative anomalies > Flashcards

Accommodative anomalies Flashcards

1
Q

Defective accomodation examples

A

Accommodative insufficiency
Accommodative fatigue
Accommodative paralysis
Accommodative inertia
Accommodative spasm- excessive

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2
Q

Defictive accommodation conditions (IFP)

A

Accomm insuffiency, fatigue, paralysis

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3
Q

Which accomodative anomaly cause a failure to accommodate

A

Accommodative inertia

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4
Q

Excessive accommodation

A

Accommodative spasm

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5
Q

Accommodative insufficiency and cause

A

The near point of accomm consistently below that expected for age and refractive error. It is usually bilateral and might be monocular if due to local trauma.
Local trauma to the eye can cause accommodative insufficiency, usually temporary – recovery may be incomplete.

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6
Q

Accommodative insufficiency

Near vision
Unioc and binoc NPA
Dynamic RET
Deviation
Micropsia

A
  • Near vision? Blurred
  • Uniocular and binocular NPA? Reduced with age
  • Dynamic ret? Increased accom lag
  • Deviation? Effort may produce eso
  • Micropsia? Rare illusion in severe cases
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7
Q

Is accommodative fatigue bilateral

A

Yes
It is when accommodation is initially sufficient but reduces with continued exertion

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8
Q

Accommodative fatigue

affect on near vision
NPA
Dynamic RET
When does it occur
Micropsia

A
  • Near vision? Blurred
  • NPA? Reduced on repeated testing (unioc and binoc)
  • Dynamic ret? Increased accom lag
  • When does it occur? With prolonged near work, can be relieved by rest
  • Micropsia? Rare
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9
Q

Accomodative inertia

A

is bilateral and there is difficulty in altering accomm - delay in either exerting or relaxing accomm

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10
Q

Is accommodative inertia bilateral

Blur
NPA
Dynamic RET
Accomodative facility

A

YES
Blur? When changing focus/distance
NPA? Possibly normal
Dynamic RET? Possibly normal accomm lag
Accommodative facility? Reduced and worse in poor illumination

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11
Q

Accomodative paralysis

Blur
NPA
Dynamic RET
Micropsia
Pupils
Photophobia
Diplopia

A

Blur? Increased blue as fixation moves from infinitity towards patient
NPA? Unable to measure
Dynamic ret? Unable to measure
Micropsia? Present
Pupils? Possibly dilated depending on aetiology
Photophobia? If pupil is dilated
Diplopia? If convergence paralysis present

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12
Q

What is macropsia

A

Objects appear larger than natural size.
When there is an excess of accommodation, reduced effort or no effort is required to focus on a near object. The brain interprets the near object producing the retinal image as being further away. The near object is judged to be a larger than normal object in the distance.

Note- Excess of accomm such as convergence spasm, retinal image is the same, don’t have to accommodate for the distance

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13
Q

What is micropsia

A

Objects appear smaller than natural size. In a defect of accommodation, excessive accommodation is required to focus on a near object. The brain interprets the retinal image as produced by an object close to the eye. The object is judged to be smaller than its natural size.

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14
Q

Cause of accommodative anomalies

A

For all anomalies side effects of medication and drugs was seen to cause all of them.
* Anticholinergics
* Neuroleptics & antipsychotics
* Bladder spasmolytic drugs
* Antihistamines (long term use)
* Antidysrhythmic drugs
* Tricyclic antidepressants

-so its important to ask pt about meds as it can reduce accommodation

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15
Q

Specific medications and effects

A

Anticholinergics e.g. Scopolamine patch used for: motion sickness, nausea, vomiting
Or used to reduced drooling in children with disabilities

-Neuroleptics and antipsychotics e.g. phenothiazines reduce accom by 40- 100% (Thaler 1979)
Bladder spasmolytic drugs e.g. proviverrine
Reduces accom in children if given a high dose (Arfwidsson, 2007)

Antidysrthymic drugs e.g. cibenzoline
Restores normal heart rhythm and can cause severely decreased accom (Frucht et al 1984)

Tricyclic antidepressants e.g. Lorazepam
(Jung et al, 2012) – found reduced accommodation, (Speeg-Schatz et al, 2001) - found it affects convergence but not accomm

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16
Q

Managing accommodative insufficiency

A

correct refractive error

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17
Q

Managing accommodative fatigue

A

treat any underlying cause

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18
Q

Managing accomodative inertia

A

orthoptic accommodative exercises

Correction of small degree of hypermetropia or astigmatism can aid symptoms
+0.75DS

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19
Q

Orthoptic accommodative exercises

A

Near point accomm – accomm push up, reverse dot card, jump exercises
Accomm facility (Sterner et al 2001)
Emphasise CLEAR rather than SINGLE vision
Simple conv exercises are more effective at improving accomm than accomm exercises!
(Horwood & Toor 2014; Horwood et al 2014)

20
Q

Other management options

A

Plus correction for near work (if no response to Tx) – low plus lenses should improve vision
Wahlberg et al (2010) suggests +1DS instead of +2DS
Bifocal wear in Downs Syndrome
?counselling/ referral to clinical psychologist
?Functional  dynamic retinoscopy (obj test) and +/- lenses

21
Q

Accommodative paralysis managment

everything but exercises

A

Treat cause (if possible), correct any refractive error, exercises aren’t suitable
* Prescribe reading addition (+ lens)
* Painted contact lens if pupil dilated
* Counselling/ referral to clinical psychologist
* Base in prism (if convergence paralysis too)
* Miotics (e.g. Pilocarpine) rarely given (Reduce accomm effort needed for clear image)

22
Q

Excessive accomodation

A

Excessive accommodation- A condition where the ciliary muscle is contracted and cannot be relaxed, therefore accommodation is continuously exerted.

23
Q

Accomodative spasm

Blur
Diplopia
Dynamic RET
Micropsia
Pupils
VA
OM

A

Blur? Yes
Diplopia? Variable ET, associated with excessive conv
Dynamic ret? Accomodative lead
Micropsia? Possible
Pupils? Miosis
VA? Reduces due to pseudo myopia
OM? Spasm on lateral gaze gives appearance of LR palsy

24
Q

What happend in pseudo myopia

A

Spasm of the ciliary muscle prevents relaxation of accommodation so distance is blurred.

25
Q

Accommodative spasm causes

A
  • Functional (underlying emotional response)
  • Late onset myopia / sudden myopic increase
  • Uncorrected hypermetropia
  • Lack of relaxation after close work (mild)
  • Manipulation of accomm to control ocular alignment (XT)
  • Closed head trauma
  • Rostral midbrain lesion
26
Q

Further accommodative spasms causes

A
  • MS
  • Increased intracranial pressure (single report Kawasaki & Borruat 2005)
  • Drugs
  • Parasympathomimetics e.g. pilocarpine – used to treat glaucoma
  • Anticholinesterase agents
  • Pula et al (2013)
  • Lit review of systemic meds which result in neuro-ophthal side effects (includes accomm) and provides some info on why these occur
27
Q

Accommodative spasm investiagation

A

Observe patient throughout testing and consistency of miosis, convergence spasm
Test abduction (may need to use doll’s head), cycloplegic refraction
NB Acute myopia can be an adverse reaction to some drugs (e.g. Topiramate – epilepsy/migraines).
no miosis and no convergence spasm

28
Q

Accommodative spasm management

not exercises

A
  • Correct refractive error
  • Re-assure and visual rest – do nothing! Will resolve if no underlying neurological disease
  • If it is a child – tell the parent to stop asking about it
  • Consider counselling / clinical psychologist – if needed to remove the stress factor
  • Cycloplegics with reading correction
  • …miotics…saline (placebo)
  • BT to medial recti (convergence spasm present).
29
Q

Considerations for accommodative spams

pcs

A
  • Premature presbyopia
  • Computer Vision Syndrome (CVS)
  • Special needs children: cerebral palsy and downs syndrome
30
Q

Premature presbyopia onset and treatment

A

Age of onset of presbyopia symptoms 40-50 years old
Treatment- plus lenses

31
Q

May purely reflect extremes of normal or be due to:

A

nutritional, envionnmental, or disease-related causes

32
Q

Nutritional, environmental, or disease-related causes

6

A
  • Sunlight (ultraviolet radiation) – premature degradation of crystalline lens (Priyambada, 2019)
  • Tobacco users (Fasih et al, 2014)
  • Type 1 Diabetes (Sırakaya et al, 2020)
  • HIV and AIDS (Mathebula & Makunyane, 2017)
  • Type 1 diabetes without diabetic retinopathy
  • HIV positive patients were on antivirals
33
Q

Computer vision syndrome

A

Complaints of computer users which include:
Eye strain, eye fatigue, burning sensations, dry eyes, irritation, redness, blurred vision, delay in focusing, diplopia

33
Q

Cause of computer vision syndrome

A

It occurs due to excessive exposure to intense light, incl blue light, from screens may result in CVS

34
Q

Use of blue light filter glasses

A

No sig effect on tear production and dry eyes but patients did report a sig improvement in (Cheng et al 2014)

Improvement in symptoms but not sig
(Dabrowiecki et al 2019)

‘The best scientific evidence currently available does not support the use of blue-blocking spectacle lenses’
(College of Optometrists, 2018)

35
Q

Computer vision syndrome management

A
  • Treat any apparent accomm or conv anomaly
  • Ensure refractive correction for distance of monitor (‘middle distance’)
  • Blinking
  • Take rest breaks
    Rosenfield (2011) review
36
Q

Cerebral palsy and accommodation - lag or lead

A

42% children have poor accommodation (Leat, 1996)

Greater accommodative lag in those with more severe motor impairments (McClelland et al, 2006).

37
Q

In cerebral palsy patients

A

Might not be able to perform accomm tests so use dynamic retinoscopy (also useful in younger patients and functional cases)

38
Q

Near pupil response cerebral palsy

A

Larger focusing error (1.1-1.7D) increasing with minus lens power. response was slower and more variable

39
Q

Sensitivity

A

the ability of a test to correctly identify patients with a disease.

40
Q

Specificity

A

the ability of a test to correctly identify people without the disease.

41
Q

SHOULD KNOW

A

Be aware of the different types of accommodative anomalies

Suggest possible aetiology

Be aware of possible findings on investigation and suggest management

42
Q

Accomodative lag is

A

response is less than the stimulus

43
Q

Accomodative lead is

A

response is more than the stimulus

44
Q

Amplitude of accomodation is

A

maximum potential increase in optical power that an eye can achieve in adjusting its focus.

45
Q

What structures are involved in accomodation

A

lens
ciliary muscle
pupil

46
Q

What is the mechanism of accomodation

A

the ciliary muscle contracts and moves the ciliary body anteriorly and deep towards the optic axis

Strabismus (46 decks)

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