Exotropia - Miriam Flashcards
What kind of people is XOT more prevalent in?
Asians
What is more prevalent intermittent or constant?
Intermittent
What are the three classifications of XOTs?
Secondary, consecutive and primary
What does secondary mean?
Pathology first and XOT follows due to visual impairment
What is a consecutive?
- Esotropia first and exotropia follows
- often constant
- may be spontaneous
- Often occurs after eso deviation (iatrogenic-post-op)—> leads to slow divergence over time
What are the two categories that a primary XOT cane be classified into?
Constant and intermittent
What is a primary constant XOT?
XOT is present at all times and is the initial problem
Why should a primary constant exotropia be examined properly?
To ensure nil pathology or neurological disease
What are three classifications of a primary intermittent XOTs?
Near, non-specific and distance
What in the history may indicate an intermittent near XOT?
- More likely in adults than children
- Complain of dipl
- Complain of problems for near work such as HAs, dipl, asthenopic sx
What would happen in a CT for an intermittent near XOT?
Near XOT and distance controlled phoria
Does an intermittent non-specific XOT have BSV at any distance?
Yes
Can intermittent nonspecific XOT present at any age group?
Yes
LWhat does an intermittent non-specific XOT mean?
Sometimes your eyes are Straight and sometimes they aren’t
With intermittent distance XOT have near or distance BSV?
Near BSV
With a child who has a intermittent distance XOT how does the child not see double in the distance?
They suppress at the distance
What is the most common of all intermittent XOTs in children?
Intermittent distance XOT
What is a symptoms a mum may notice with a child intermittent distance XOT?
They may close one eye in bright light
What is a true distance XOT?
They have near BSV and distance XOT
What is a simulated distance XOT?
At distance they are XOT but at near they are managing to compensate
What are two ways someone may be simulating an XOT?
- High AC/A ratio
- Using fusion
How would you tell if a px has a high AC/A that causes a simulated distance XOT?
Present a +3.00DS to them which relaxes accommodation and will cause them to decompensate to a manifest constant XOT
How would you tell if a px’s fusion is causing a simulated distance XOT?
Use patching for about 30 mins and there will be a larger angle of deviation compared to before the patching
What key information should you ask in history when investigating an XOT?
- Age of onset
- Type/frequency (constant or intermittent)
- Symptoms
- POH (glasses, amb, pathology, previous surgery?)
- GH (milestones, chronic health, neurological)
What type of XOT is amblyopia more prevalent in?
Constant and consecutive and secondary XOT from pathology
In what case will an intermittent XOT cause amblyopia?
If they decompensated and untreated in child
How would you investigate an XOT?
- Cover test
- Ocular motility
- Near point of convergence
- Investigation of BV function (simultaneous perception/sensory, fusional reserves, stereopsis)
- Measure angle (PCT ect)
- Measurement of suppression
- AC/A ratio
- Cyloplegic refraction
- Fundus and media examination
What would a cover test show about an XOT?
- size deviation
- intermittent or constant
- Near or distance
What should you note when doing ocular motility?
Versions and ductions (common for limitations with prev strab surgery)
Scars on sclera from surgery
A or V patterns
What would you note form near point of convergence when assessing XOT?
How well they are controlled at near
(distance XOT that may decompensate to a constant XOT)
Under what conditions should stereopsis be done for a XOT px?
Where they are controlled, for example if they have an intermittent distance XOT, would asses stereopsis at near
If a px had an intermittent distance XOT, what binocular function tests would you use?
Lang, Randot, TNO, fusion range for near, 20^BO both eyes
If a px had an intermittent near XOT, what BV tests would you use?
Synoptophore, FD2 distance stereotest, fusion range distance
How would you measure the deviation?
Prism cover test - GOLD STANDARD
Prism reflection test
Krismsky
AT NEAR AND DISTANCE and maybe FAR distance
In what instance would you use a Krismsky?
If they have poor vision
In order to determine if a distance XOT is simulated or true what would you do?
With +3.00DS either eye at near with PCT (increased near angle simulated by accommodation) and after 45 minutes of occlusion with PCT (increased angle simulated by fusion)
How is suppression measured?
Post-operative diplopia test to simulate what it would be like for after surgery
Why is a fundus and media examination important?
To exclude pathology
Why would someone do reconstructive surgery?
For cosmetic purposes
Why have you got to be careful when carrying out reconstructive surgery?
If px is asymptomatic and they are suppressing after surgery they may get diplopia
What are four principles you must consider for management
- Correct diagnosis
- Achieve best VAs in each eyes
- Functional cure
- Reconstructive cure
What is functional cure?
Restoring BSV at all distances
What is reconstructive cure?
Improving Cosmesis to make XOT smaller
Is a secondary XOT more common in older or younger patients ? + is it more likely to be constant or intermittent?
older patients + constant unilateral (because pathology is constant)
Should you refer children under 2 with a primary constant xot?
Yes
What is the first stage management of XOT?
- refractive correction
- amblyopia treatment for under 7s
- Fundus examination
Should you under correct small degrees if hyperopia for px with XOT?
Yes
How can you delay surgery with a px with XOT in relation to manipulation of rx?
Over minus
In an adult px what prism would you give if surgery is contra indicated or delclined?
Base in
Do prims treat the problem?
No
What orhtoptic exercises can you give for XOT?
- positive relative vergence
- dot card
What are six reasons to refer an XOT px to the HES?
- pathology concerns
- prevent amb
- treat amb
- give exercises
- surgery
- Botox
Is Botox a predictable outcome?
No
What are three reasons surgery would be undertaken for XOT PX ?
- intermittent is decompensating
- symptomatic
- Poor cosmesis
Why is a child with a decompensating intermittent distance XOT concerning ?
They may decompensate and get amb and lose bsv
What is the management for secondary XOT?
- give significant rx
- refer hes for undiagnosed issue
- treat amb
- treat for cosmesis purposes
What are two cosmetic treatments for px with secondary XOT?
Strabismus surgery + Botox for older children
What is the management for consecutive XOT for under 8 yrs old?
- give significant rx
+ refer for: - treat amb
- prevent loss of bsv
What is the management for a px with consecutive XOT for over 8s who are not happy with appearance or sx?
- give significant rx
- small XOT then under correct hyperopia
Refer to hes for :
- bi prism to give bsv
- surgery
- Botox
What is the management for a px with constant XOT for an under 8?
- Correct any rx
- Refer for ocular or neurological associations + amb treatment + prevent bsv loss
Why would you refer over 8s to hes with a constant XOT?
- cosmesis purposes
- symptomatic
- older kids with RFs for further investigation
Once referred to hes, what will they do to treat constant XOT?
Surgery or Botox
What is the management for over 8s with constant XOT?
correct any rx and consider referral to hes
What is the management for near XOT?
- correct significant rx and under correct small hyperopic rx
- refer if under 8
is it liekly to have a child under 8 with an intermittent near XOT?
Unlikely
What prisms would you give for a near XOT?
Base in
In what cases would you suggest orthoptic exercises?
- deviations less than 20^d
- to improve BO fusion range
- to improve convergence
At the hes, what may they do to treat near XOT?
Surgery or Botox
What is the management for non-specific XOt?
-correct significant rx
- refer under 8 for amb + prevent loss of bsv
- refer over 8s for cosmesis
Does a px with non-specific XOT often have symptoms?
No
What are the cosmetic treatment for a px with non-specific XOT?
Surgery and Botox
What is the management for a child under 8 with intermittent distance XOT?
- give significant rx
- refer to hes
What must you include when you are referring an intermittent distance XOT under 8 year old px?
They are well controlled at near
If they are older than 8 years old why would you refer an intermittent distance XOT px?
Cosmesis
Why should you no rush surgery if a px with distance XOT has good control at near?
- risk of loss of bsv
- risk of amb
- risk of consecutive sot due to inaccurate measurements
What is the hes job when managing intermittent distance XOT?
- Ensure controlled and not deteriorating
- potentially over minus
- surgery
- Botox
What is the likely diagnosis?
Cover tests with accommodative target small XOP good recovery. Cover test are near with +3.00 r&l moderate XOT. Cover test at distance moderate XOT?
Intermittent distance simulated XOT