Approach to amblyopia and strabismus (pediatrics): Clinical sciences

Chapters:

Watch video only

Introduction0:00–0:32

Amblyopia, sometimes called lazy eye refers to decreased visual acuity in one or both eyes that prevents normal development of the visual cortex.
It's crucial to identify amblyopia at a young age before it becomes difficult or even impossible to treat common causes of amblyopia include strabismus or misalignment of the eyes as well as deprivation and refractive error.

History and physical examination0:32–2:45

Now, if a pediatric patient presents with a chief concern, suggesting amblyopia or a strabismus, first perform a focused history and physical examination, including visual acuity and red reflex testing.
Visual acuity testing techniques vary by age for Children. Under age two, you can assess the pupillary response to light as well as the ability to track or fixate on and follow an object.
After age three, most Children can recognize and match objects on cards and when they're older, they can read an eye chart for younger Children or those who are unable to cooperate with standard testing, consider instrument based screening with a photo screener or autorefractor.
Remember to perform vision screening monocularly at a specified distance and make sure your patient wears corrective lenses if they were prescribed.
Now to perform the red reflex test view, both eyes through an ophthalmoscope and look for a symmetric red reflection from the retina.
You'll find it helpful to turn off or dim the lights to ensure the pupils are dilated. All right, let's look at some findings you might see in Children with amblyopia or a strabismus.
Although young Children are often asymptomatic history might reveal blurred vision or vision loss. And caregivers may describe a lazy or deviated eye as well as squinting or head tilt, also called ocular torticollis.
Infants may demonstrate a lack of eye contact. The physical examination typically reveals a unilateral or bilateral decrease in visual acuity for verbal Children.
Testing with a standard vision chart may reveal a two line difference in vision between both eyes for infants or preverbal Children.
Signs of visual loss include decreased following or fixation and a fixation preference. With these findings consider amblyopia next, assess for a history of eye deviation.

Strabismus amblyopia2:45–3:42

And if present, consider strabismus amblyopia, then perform corneal light reflection and cover uncover tests to look for corneal misalignment to test corneal light reflection.
Have your patient look straight ahead and shine a light directly onto the cornea of both eyes. If the light reflex is symmetric and centered in each pupil, the eyes are straight but an asymmetric reflex suggests pupillary deviation or misalignment to perform the cover uncover test.
Have your patient fixate on an object in the distance and then cover and uncover each eye. If the uncovered eye drifts after you cover the opposite eye, your patient has ocular misalignment.

Pseudostrabismus3:42–4:40

Now, if neither of these tests show evidence of ocular misalignment, consider pseudo strabismus, which means there appears to be misalignment when the eyes are in fact straight.
Some anatomic characteristics that can give the false appearance of ocular misalignment include a flat broad nasal bridge, prominent epicanthal folds or a narrow interpupillary distance.
If any of these features are present, your patient has pseudostrabismus. This benign condition doesn't cause amblyopia and it typically diminishes as the child grows.
Here is a clinical pearl, intermittent strabismus is a normal finding during the first few months of life. But if strabismus is constant or if it doesn't resolve after four months of age, your patient requires further evaluation.

Strabismus (Heterotropia)4:40–5:20

On the other hand, if the corneal light reflection test or cover uncover test demonstrates persistent corneal misalignment, diagnose strabismus also known as heterotropia.
Here is a high yield fact. While performing the cover on cover test, you may discover an intermittent or a latent misalignment called heterophoria.
In this case, misalignment or deviation only occurs during periods of fatigue or stress. Heterophoria can occasionally result in eye strain, headaches or double vision, but it does not cause amblyopia.

Comitant tropia5:20–6:15

All right. Once you diagnose your business, your next step is to assess the consistency of eye deviation.
If ocular deviation is equal and consistent regardless of gay's direction, your patient has a comitant tropia to determine the specific type, assess the direction of ocular deviation if either eye deviates, inward diagnose esotropia.
This is the most common type of ocular misalignment in Children on the flip side. If either eye deviates outward diagnose exotropia.
Here's another clinical pearl comitant tropis can be congenital or acquired while they can sometimes result from structural eye or brain abnormalities.
The underlying cause is usually unknown. Ok.

Noncomitant tropia6:15–8:51

Let's go back and talk about patients with eye deviation that varies with the direction of gaits. In this case, consider noncomitant tropia, sometimes called paralytic tropia.
Noncomitant tropis can be congenital or acquired and are caused by limitations in extraocular muscle movements, usually due to paralysis or paresis.
This ultimately leads to an imbalance in gaze deviation. Now you can subcategorise noncomitant tropis according to the affected cranial nerve, to determine which nerve is involved, assess the direction of eye deviation.
If the eye is deviated outward, called exotropia and downward called hypotropia. Consider the third cranial nerve palsy.
Here, the patient might have a developmental anomaly or a history of birth trauma. The exam typically demonstrates down and out eye deviation with ptosis, possibly in combination with pupillary dilation or paradoxical movements of the lid eye and pupil.
These findings are consistent with a third nerve palsy. Alternatively, if the eye is deviated upward, called hypertropia, consider the fourth cranial nerve palsy affected patients often present with a head tilt and there might be a history of head trauma.
Most cases of fourth nerve palsy are congenital. But because this nerve has a long intracranial course, it's at an increased risk of damage in patients with head trauma.
If the exam reveals vertical upward misalignment of the eye, that's 1/4 nerve palsy. Finally, if deviation is inward called esotropia, consider the sixth cranial nerve palsy.
These patients typically demonstrate eye crossing, limited lateral eye movement and head turning. Some may have a history of trauma, vascular malformation or meningitis.
In addition to esotropia, the exam might reveal papilledema. These findings are consistent with 1/6 nerve palsy.
Keep in mind that acquired sixth nerve palsies should raise your suspicion for increased intracranial pressure which could be caused by head trauma, hydrocephalus or intracranial tumors.
Now, let's go all the way back and talk about patients without eye deviation. In this case, consider refractive or deprivation amblyopia as a next step, perform a complete eye exam with fundoscopy to check for an obstruction within the visual access.

Refractive and deprivation amblyopia8:51–9:15

Deprivation amblyopia9:15–9:53

First, let's talk about what you might see in patients with deprivation, amblyopia, external findings that can obstruct the vision include ptosis or periorbital hemangioma.
Red reflex testing might reveal leukocoria which indicates an intraocular opacity along the visual axis. You might also see in intraocular mass, a cornea or lens opacity or a vitreous hemorrhage.
Any of these findings indicates an obstruction within the visual axis which is causing deprivation, amblyopia. Ok.

Refractive amblyopia9:53–10:57

If you see no evidence of obstruction, consider refractive amblyopia and perform refractive testing. Traditionally, objective refractive testing involves dilating the pupils and projecting light onto the retina with a retinoscope.
Then using lenses, you can measure the refraction of the eyes. You can also use autorefractor devices to measure refraction for older patients.
You can perform subjective refractive testing to do this place lenses in front of each eye and ask the patient to report which lenses provide the clearest images from an eye chart.
Now, if testing confirms a refractive error, diagnose refractive amblyopia. Here's one more pearl refractive amblyopia can be caused by myopia hyperopia or astigmatism in one or both eyes.
But the most common cause is unilateral unbalanced hyperopia. All right, as a quick recap when a pediatric patient presents with a chief concern, suggesting amblyopia or strabismus obtain a focused history and physical and perform visual acuity and red reflex testing.

Review10:57–12:13

A history of eye deviation should make you consider strabismus. If corneal light reflection and cover uncover tests don't reveal misalignment diagnose pseudostrabismus.
But if either confirms misalignment, diagnose strabismus deviation that persists regardless of gaze direction indicates a comitant tropia like esotropia and exotropia.
However, deviation that varies with the direction of the gaze indicates a noncomitant tropia like 3rd, 4th or sixth cranial nerve palsies, if there is no eye deviation, but you identify an obstruction within the visual axis, diagnose deprivation amblyopia.
However, if there is no obstruction and testing reveals a refractive error, diagnose refractive amblyopia