Ophthalmology – Strabismus: By Yi Ning Strube M.D.

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Ophthalmology – Strabismus
Whiteboard Animation Transcript
with Yi Ning Strube, MD
https://medskl.com/Module/Index/strab...


Strabismus, or misalignment of the eyes, can have many different causes. When I examine a patient with strabismus, I always try to determine if the strabismus is comitant or incomitant. Comitant strabismus means that the angle of deviation is the same in all positions of gaze and the extraocular movements are full. Incomitant strabismus, means that the angle of deviation is different in different positions of gaze, and the extraocular movements are not full.

Incomitant strabismus is a worrisome sign and is something that you cannot afford to miss. , as it may be caused by either restriction or paralysis of the extraocular muscles.

Restriction – or trapping or shortening of the muscle – can be due to ocular trauma, orbital inflammation or orbital tumour.

Paralysis, or loss of proper innervation to the muscle, can be due to one or a combination of the cranial nerves not working properly.

A diagnosis you cannot afford to miss is a palsy of the 3rd cranial nerve. This will present with limited eye movements, typically an inability to elevate, depress and adduct the eye, with the eye presenting in a down and out position. The eyelid will be droopy and the pupil may be involved and dilated.

A pupil-involving 3rd nerve palsy is an emergency due to the possibility of a brainstem aneurysm and neuroimaging must be ordered immediately.

A 6th cranial nerve palsy is another diagnosis you cannot afford to miss. It can present with an inturned eye, called esotropia, and limited abduction in one or both eyes.

If associated with disc swelling or papilledema, neuroimaging must be ordered emergently to rule out raised intraocular pressure due to intracranial pathology.
In a child, strabismus and amblyopia can be the presenting signs of a serious eye problem. Retinoblastoma, a white tumour of the retina, and congenital cataract are two diagnoses that you cannot afford to miss. If missed, retinoblastoma can cause blindness, loss of the eye and even death. Congenital cataract if not treated urgently can cause blindness.

To rule these conditions out, all children should be examined for a normal red reflex with a direct ophthalmoscope during routine check-ups starting from birth. If the red reflex in one or both eyes is dark or white, this indicates something is blocking the light from entering the eye and could be a sign of retinoblastoma or congenital cataract and must be referred to ophthalmology immediately.