Pseudo-Strabismus Flashcards
(23 cards)
What is a pseudo-strabismus?
The clinical impression of a manifest ocular deviation when no squint is present
What are the main possible causes of a pseudo-strabismus?
Facial asymmetry (receding brow makes eyes appear inward, prominent cheekbone makes eyes appear outward, angle kappa), IPD, Wide Nasal Bridge or Prominent Epicanthal Folds
How does a wide nasal bridge make it look like someone has a pseudo-strabismus?
Because the inner corner of the eye (medial canthus) is further away from the nose than the outer corner (lateral canthus)
What are epicanthal folds?
Small folds of skin that cover the inner corner of the eye (medial canthus).
How is the severity of epicanthal folds seen?
Based on the degree of caruncle obstruction which correlates to how much we think there’s a deviation of the eyes
Who are severe epicanthus folds more common in?
Some Asian populations and a feature of genetic disorders like Trisomy 21, Noonan’s Syndrome and Zellweger Syndrome
What are the 4 different types of epicanthus?
1) Tarsalis
2) Inversus
3) Palpebralis
4) Superciliaris
What is Tarsalis?
A type of epicanthus fold. Primarily involves the upper eyelid and then extends medially and dissipates
What is Inversus?
A type of epicanthus fold. Most prominent along the lower eyelid
What is Palpebralis?
A type of epicanthus fold. Symmetrically involves both upper and lower eyelids.
What is Superciliaris?
A type of epicanthus fold that extends from the eyebrow and follows down to the lacrimal sac.
What is BPES?
A rare developmental condition affecting the eyelids called ‘Blepharophimosis, ptosis, epicanthus inversus syndrome’ caused by a mutation of the FOXL2 gene
What are the 4 facial features at birth of BPES?
1) Narrow Eyes
2) Droopy Eyelids
3) Wide-Set Eyes
4) Upward fold of skin of the inner lower eyelids
What are the average IPD’sfor adults and children?
Children - approx 45-55mm
Adults - approx. 55-65mm
What pseudo-deviation do wide or narrow IPD’s cause?
Wide = Exotropic
Narrow = Esotropic
What is angle kappa/alpha?
It’s the angle between the optical axis and the visual axis that occurs as the fovea isn’t in the geometric centre of the eye (as it’s slightly temporal)
What angle kappa gives rise to slightly nasal corneal reflections?
Positive Angle Kappa (PDN)
What are other causes of pseudo-squint that aren’t the main causes?
- Corectopia (pupils displaced) - the type of deviation depends on direction of displacement
- Facial Asymmetry - appearance of vertical deviations
- Ectopic Macula - Foveal region displaced by pathology giving rise to a change between visual axis and pupillary line
- Exophalmos - Eyes protrude and can look exotropic. Associated with Grave’s Disease
- Enophalmos - Sunken eyes that can look esotropic. Rarer but seen in orbital blowout fractures.
- Coloboma
- Heterochromia
What is Coloboma?
It’s Greek for ‘curtailed’ meaning conditions where normal tissue in or around the eye is missing from birth. It affects the eyelid, lens, macula, optic nerve and UVEA
How does Heterochromia cause a pseudo-strabismus?
Where lighter eyes appear more Exo and if partial, the deviation looks to be in the direction of the lighter portion
What are the clinical presentation of pseudo-strabismus?
- Health visitors refer
- Typically present at > (or equal to) 6mo
- Thorough case history
- Vague history e.g. unsure of direction, when, etc.
- If improving or not
- No visual concerns
- Photos shown may not be face-on
How do we diagnose a pseudo-strabismus?
Diagnosis of exclusion!
- Vision assessment - if occlusion resistant use things like Cardiff Cards. Equal vision is usually a good sign if no squint is present.
- Symmetrical corneal reflections
- Cover test doesn’t show a manifest strabismus
- Check refraction, fundus and media
- Full orthoptic report to prove normal BSV and ocular alignment e.g. overcome 20PD and stereopsis
How do we manage a pseudo-strabismus?
The majority of the time it doesn’t require active management!
- Reassure parents
- Explain development of nasal bridge (or whatever it may be)
- Family history of squints
- Can discharge at 1st visit if VA is good and have BSV
- Ask parents to come back if it doesn’t resolve with time. If unresolved it may require surgery or cause management if the epicanthus persists and remains large, that they have ptosis or other lid anomalies or have craniofacial disorders
