Strabismus and Amblyopia

Question 1

Amblyopia

Answer 1

Decreased vision that results from abnormal visual development in infancy and early childhood.
Can happen even w/ no problem in eye structure.

Question 2

How does amblyopia happen w/out structural eye problem?

Answer 2

Mismatched images to brain from each eye. Lower functioning eye doesn’t develop properly.

Question 3

Amblyopia epidemiology

Answer 3

Responsible for more unilaterally reduced vision than all other causes
2-4% in N. America
Almost all types preventable or reversible if treated early
EARLY RECOGNITION = EARLY TREATMENT = BETTER OUTCOMES

Question 4

Strabismic amblyopia

Answer 4

Ocular misalignment

Double vision due to crossed eye is suppressed by brain in children

Question 5

Strabismus

Answer 5

Eye misalignment

Question 6

ESO

Answer 6

inward deviation

Question 7

EXO

Answer 7

outward deviation

Question 8

HYPO

Answer 8

downward deviation

Question 9

HYPER

Answer 9

upward deviation

Question 10

Orthophoric

Answer 10

Straight eye

Question 11

Pitfalls of strabismus terms

Answer 11

Must name which eye when talking about hyper- and hypo-

May change w/ gaze position

Question 12

Tropia

Answer 12

Manifest strabismus, exists even when both eyes are open and attempt to work together
Large angles are obvious

Question 13

Manifest strabismus

Answer 13

Misalignment of eyes that is always there

Question 14

Detecting small angle manifest strabismus

Answer 14

Cover-Uncover test

Question 15

Phoria

Answer 15

Latent strabismus, such as when fusional mechanism between two eyes is broken by covering one eye via Cross-Cover Test

Question 16

Latent strabismus

Answer 16

Misalignment of eyes that occurs some of the time

Typically more prominent when tired, ill, intoxicated, etc.

Question 17

Congenital/Infantile Strabismus

Answer 17

Infantile esotropia
Accommodative esotropia
Intermittent exotropia

Question 18

Paralytic Strabismus

Answer 18

Cranial Nerve Palsy

Question 19

Restrictive Strabismus

Answer 19

Thyroid eye disease

Question 20

Essential Infantile Esotropia

Answer 20

Present w/in first 6 mo.
Signs:
Angle large and stable
Nystagmus in some cases
Normal refraction for age
Amblyopia in about 30% (Cross-fixation causes decreased amblyopia because infant will fixate with esotropic eye also)

Question 21

Accomodative Esotropia

Answer 21

Onset 18mo - 4yo
Eye crossing inward caused by the focusing efforts of eyes as they try to see clearly, especially up close
Typically in hyperopic (farsighted) pt.
Overstimulated convergence reflex when looking up close
Glasses usually correct this

Question 22

Intermittent Esotropia

Answer 22

Onset 10mo - 4yo
Worse w/ fatigue/illness
Usually alternating (amblyopia uncommon)
Can worsen to constant exotropia if not treated early and properly

Question 23

Anisometropia

Answer 23

Refractive amblyopia type
Significantly different refractive errors between the two eyes
Brain “shuts down” worse eye.
Needs early tx or may have permanent vision loss

Question 24

Isometropia

Answer 24

Refractive amblyopia type

Too near sighted tor too far sighted

Question 25

Form deprivation/Occlusive amblyopia

Answer 25

Occurs w/ opacities of ocular media (cataract, corneal scar)
Check w/ red reflex. Usually congenital cataracts from birth.
Operate before 6 wks w/ unilateral cataract
Operate before 10 wks w/ bilateral cataract

Question 26

Peds Eye Exam Hx/Inspection

Answer 26

History

Inspection: Does the child fixate? Any obvious deviations?

Question 27

Peds Eye Exam Sensory Testing

Answer 27

Worth 4 Dot Test (red and green lights)
Stereopsis Test
Test binocular function prior to other monocular testing
Inhibition is a common visual dysfunction

Question 28

Corneal light reflex test

Answer 28

Hirschberg reflex w/ penlight for corneal white light

Bruckner reflex test w/ direct ophthalmoscope for red reflex

Question 29

Pseudo-esotropia

Answer 29

Wide, flat nasal bridge creates illusion of misalignment

Question 30

Bruckner Reflex

Answer 30

Assess for leukocoria, strabismus, anisometropia, anisocoria

Evaluates red reflex: Quality/Intensity, Pupil size, Position of light reflex, Qualtiy of corneal light reflexes.

Lights should be MIRROR IMAGES!! ANY ASSYMETRY? OPHTHO REFERRAL!!

Question 31

Cover Uncover Test

Answer 31

Detects tropia
Alternate cover test breaks fusion, detects phoria
Prism cover test measures total deviation

Question 32

Visual acuity testing in infants-2yo

Answer 32

Fix and Follow
Central, Steady, Maintain (CSM) = normal
Unsteady = Nystagmus
Central, Steady, Unmaintained = Amblyopia

Question 33

Visual acuity testing in 2-5yo

Answer 33

Allen Picture chart
E chart
HOTV chart

Question 34

Visual acuity testing >5yo

Answer 34

Snellen chart

Question 35

Amblyopia Tx

Answer 35

Glasses correction for optical errors
Patching
Atropine penalization
MAKE THEM USE THE LAZY EYE

Question 36

Strabismus Tx

Answer 36

Refractive error correction (especially in accommodative esotropia due to hyperopia/farsightedness)
Prism
Eye muscle surgery (last resort)

Question 37

Alternate Cover Test

Answer 37

Phoria test. performed after the single cover test. Occludes one eye and then the other, switching the occluder back and forth to occlude the eyes without allowing the patient to fuse in between occlusion. Most dissociative cover test and measures a total deviation, including the tropic plus the phoric/latent component. Important to hold the occlude over each eye for at least a few seconds, in order to allow the non-occluded eye enough time to pick up fixation. In general, the faster the eyes are able to recover when the occluder is switched, the better the control of the deviation.