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Heterotropia Cheat Sheet (DRAFT) by

Hetetrotropia: Classification, Microtropia and Management

This is a draft cheat sheet. It is a work in progress and is not finished yet.

What is a Hetero­tropia?

Also known as a stabismus, it is a manifest deviation, wherein the eyes are misaligned under normal binocular viewing conditios
Tropias may be constant or interm­ittent
Tropias may affect one eye or alternate between both
In early childhood, tropias may cause an amblyopia (lazy eye)
Tropias may or may not be linked to refractive error
Tropias may or may not be linked to accomm­odation and conver­gence
A comitant hetero­tropia is one where the angle of deviation remains the same in all directions of gaze, regardless of which eye they use

Hetero­tropia Classi­fic­ation



Patients look like they have a strabismus but they don't
Common in children with epicanthal folds as it mimics esotropia
Also patients with a positive angle Kappa, where the corneal light reflex is displaced nasally, can look like they have an exotropia
Here, you should perform a cover test to double check

IPE: Accomm­odative

Esotropia disappears when the hyperm­etropia is fully corrected
Usually arises between 2-5 years
Amblyopia is uncommon unless the hyperm­etropia has been uncorr­ected for a long time. E.g. the problem not picked up at an early age
Usually normal BSV with glasses on
Management - perform cyclop­legic refraction and issue a full prescr­iption.
Treat the amblyopia if present.
If there's low amounts of hyperm­etropia and astigm­atism, exercises might help to reduce the need to wear glasses as child gets older (over 8)
Most patients will always need to wear glasses or contact lenses

Invest­iga­tion: Key Things to Note

Their age - if young, it may be linked to amblyopia and impact their visual develo­pment, if a little older, was it acquired?
If the tropia is new or longst­anding
Is it causing any symptoms?
Is it present all the time, why not if not?
Are any adapta­tions present?
Is referral required?

Invest­iga­tion: Concluding Inform­ation

The type of test you perform and the expected outcome depends on your prelim­inary diagnosis
Usually, if the tropia isn't causing a problem, then it isn't much of a worry. Measur­ements may be helpful to monitor. Tailor your test to their binocular status and move on
If the tropia is causing a problem and the px is sympto­matic, they warrant further invest­igation
In young children, squints need careful invest­igation to determine the cause and approp­riate manage­ment!!


Primary Esotropia
Secondary Esotropia
Consec­utive Esotropia
Constant: partially accomm­odative or non accomm­odative
Results from a loss of vision
Due to a surgical overco­rre­ction of an exotropic strabismus
Interm­ittent: fully accomm­oda­tive, conver­gence excess, relates to fixation distance e.g. at distance or near, non-sp­ecific

CPE: Non-Ac­com­mod­ative

Esotropia present all the time and unaffected by the accomm­odative state
Deviation may alter between both eyes
For example, infantile esotropia. Has an early onset in the first year of life usually before 6 months and is a large angle often >30. Could be an altern­ating deviation, thus VA good in both eyes Dissoc­iated vertical deviation may be present Not associated with hyperm­etropia
Management - correct the refractive error and treat the amblyopia. May require surgery to align the visual axes and allow normal BSV to develop. Best to perform before they're 2.

Invest­iga­tion: Relevant Clinical Tests

Case history alongside observing patient
Visual acuity at both distance and near
Cover test with and without prism bar
Ocular motility
Suppre­ssion tests e.g. worth 4 dot test, 4 base out prism
Accomm­odation and Covergence
Bagolini lenses
Patient invest­iga­tions would depend on whether the tropia is new or longst­anding (esp. in an adult), depend on whether patient is a child, and whether the tropia is constant or interm­ittent

CPE: Partially Accomm­odative

Esotropia present at all time and increases in size when patient accomm­odates
Deviation size reduces when the hyperm­etropia is corrected but it is still present
Occurs in early childhood (ages 1-3)
Anomalous retinal corres­pon­dence may be present
Dissoc­iated vertical deviation may be present (different from vertical tropia where only 1 eye deviates upwards)
Manage­ment: fully correct the refractive error, treat the amblyopia (as they're childr­en!), only refer for surgery in extreme cases