Accommodative anomalies Flashcards
Defective accomodation examples
Accommodative insufficiency
Accommodative fatigue
Accommodative paralysis
Accommodative inertia
Accommodative spasm- excessive
Defictive accommodation conditions (IFP)
Accomm insuffiency, fatigue, paralysis
Which accomodative anomaly cause a failure to accommodate
Accommodative inertia
Excessive accommodation
Accommodative spasm
Accommodative insufficiency and cause
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.
Accommodative insufficiency
Near vision
Unioc and binoc NPA
Dynamic RET
Deviation
Micropsia
- 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
Is accommodative fatigue bilateral
Yes
It is when accommodation is initially sufficient but reduces with continued exertion
Accommodative fatigue
affect on near vision
NPA
Dynamic RET
When does it occur
Micropsia
- 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
Accomodative inertia
is bilateral and there is difficulty in altering accomm - delay in either exerting or relaxing accomm
Is accommodative inertia bilateral
Blur
NPA
Dynamic RET
Accomodative facility
YES
Blur? When changing focus/distance
NPA? Possibly normal
Dynamic RET? Possibly normal accomm lag
Accommodative facility? Reduced and worse in poor illumination
Accomodative paralysis
Blur
NPA
Dynamic RET
Micropsia
Pupils
Photophobia
Diplopia
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
What is macropsia
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
What is micropsia
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.
Cause of accommodative anomalies
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
Specific medications and effects
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
Managing accommodative insufficiency
correct refractive error
Managing accommodative fatigue
treat any underlying cause
Managing accomodative inertia
orthoptic accommodative exercises
Correction of small degree of hypermetropia or astigmatism can aid symptoms
+0.75DS
Orthoptic accommodative exercises
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)
Other management options
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
Accommodative paralysis managment
everything but exercises
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)
Excessive accomodation
Excessive accommodation- A condition where the ciliary muscle is contracted and cannot be relaxed, therefore accommodation is continuously exerted.
Accomodative spasm
Blur
Diplopia
Dynamic RET
Micropsia
Pupils
VA
OM
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
What happend in pseudo myopia
Spasm of the ciliary muscle prevents relaxation of accommodation so distance is blurred.
Accommodative spasm causes
- 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
Further accommodative spasms causes
- 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
Accommodative spasm investiagation
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
Accommodative spasm management
not exercises
- 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).
Considerations for accommodative spams
pcs
- Premature presbyopia
- Computer Vision Syndrome (CVS)
- Special needs children: cerebral palsy and downs syndrome
Premature presbyopia onset and treatment
Age of onset of presbyopia symptoms 40-50 years old
Treatment- plus lenses
May purely reflect extremes of normal or be due to:
nutritional, envionnmental, or disease-related causes
Nutritional, environmental, or disease-related causes
6
- 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
Computer vision syndrome
Complaints of computer users which include:
Eye strain, eye fatigue, burning sensations, dry eyes, irritation, redness, blurred vision, delay in focusing, diplopia
Cause of computer vision syndrome
It occurs due to excessive exposure to intense light, incl blue light, from screens may result in CVS
Use of blue light filter glasses
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)
Computer vision syndrome management
- Treat any apparent accomm or conv anomaly
- Ensure refractive correction for distance of monitor (‘middle distance’)
- Blinking
- Take rest breaks
Rosenfield (2011) review
Cerebral palsy and accommodation - lag or lead
42% children have poor accommodation (Leat, 1996)
Greater accommodative lag in those with more severe motor impairments (McClelland et al, 2006).
In cerebral palsy patients
Might not be able to perform accomm tests so use dynamic retinoscopy (also useful in younger patients and functional cases)
Near pupil response cerebral palsy
Larger focusing error (1.1-1.7D) increasing with minus lens power. response was slower and more variable
Sensitivity
the ability of a test to correctly identify patients with a disease.
Specificity
the ability of a test to correctly identify people without the disease.
SHOULD KNOW
Be aware of the different types of accommodative anomalies
Suggest possible aetiology
Be aware of possible findings on investigation and suggest management
Accomodative lag is
response is less than the stimulus
Accomodative lead is
response is more than the stimulus
Amplitude of accomodation is
maximum potential increase in optical power that an eye can achieve in adjusting its focus.
What structures are involved in accomodation
lens
ciliary muscle
pupil
What is the mechanism of accomodation
the ciliary muscle contracts and moves the ciliary body anteriorly and deep towards the optic axis
