Pediatric Opthalmology

Question 1

Functional reduction in the visual acuity of an eye, either unilaterally or bilaterally, caused by disuse or misuse during the critical period of visual development
Functional reduction in visual acuity of eye

Answer 1

Amblyopia

Question 2

What is the most common cause of pediatric visual impairment

Answer 2

Amblyopia

Question 3

What causes amblyopia?

Answer 3

• Abnormal vision development in infancy/childhood
• Unilateral or bilateral
• Brain receives poor image from eye and thus does not “learn to see well”
• Vision loss because nerve pathways between brain and eye are not properly stimulated

Question 4

Risk factors for amblyopia

Answer 4

• Prematurity
• First degree relative with amblyopia
• Small size for gestational age
• Neurodevelopmental delay

Question 5

Classifications of amblyopia

Answer 5

• Strabismus
• Refractive
• Deprivational

Question 6

Misalignment of visual axes of the two eyes

Answer 6

Strabismus

Question 7

One or both eyes having refractive error causing imbalance between eyes

Answer 7

Refractive

Question 8

Obstruction by a cataract or complete ptosis prevents formation of a formed retina

Answer 8

Deprivational

Question 9

What is strabismic amblyopia?

Answer 9

• One eye may turn in, out, up, or down
• Described by direction of deviation
• Brain ignores or turns off eye that is not straight and vision drops in that eye
• Foveas of the two eyes are presented with two different and unfusable images
• Visual cortex suppresses image from one eye in order to avoid having diplopia; long term suppression of one eye results in strabismic amblyopia

Question 10

What is refractive amblyopia?

Answer 10

• Most commonly due to asymmetric refractive error
• Foveas of two eyes presented with different image clarity d/t unequal uncorrected refractive errors; image in one eye not focused on the fovea at same time as the other
• Brain does not learn how to see wellfrom the eye that has a great need for glasses
• Most commonly in hyperopic (farsighted)

Question 11

When is refractive amblyopia most often detected?

Answer 11

• Older age than strabismic amblyopia because children with refractive amblyopia lack obvious external abnormalities and visual functioning appears normal because see well with fellow eye
• Often diagnosed at first vision screening when old enough to identify letters or figures (ages 4 or 5)

Question 12

What is deprivational amblyopia?

Answer 12

• Least common form but most severe
• Results from vision deprivation, typically as result of interruption of visual axis or severe distortion of foveal image
• Congenital cataracts, ptosis, congenital corneal opacities, vitreous hemorrhage, and severe refractive errors may cause
• Results in permanent visual impairment if not treated urgently

Question 13

Amblyopia evaluation in pre-verbal child

Answer 13

• Fixation reflex
• Differential occlusion objection test

Question 14

What is fixation reflex? How will it present in amblyopic eye?

Answer 14

• Testing involving moving visual target to and from child’s visual space, each eye tested by occluding fellow eye
• Amblyopia will rarely maintain fixation with amblyopic eye when both eyes uncovered

Question 15

Differential occlusion objection test

Answer 15

• Monitor child’s response to alternate occlusion of eyes
• Children with equal vision respond equally, or not at all
• Children with moderate-to-severe visual impairment in one eye become more irritable when other eye with better vision occluded

Question 16

Amblyopia evaluation in verbal child 3 and older

Answer 16

• Allen or Snellen charts for visual acuity

Question 17

How is visual acuity assessed?

Answer 17

• Attempt at 3 years of age and older
• Snellen chart measured at 20 ft and marked off
• Begin with 20/40 and if child misses 2 figures in a row, ask child to go up a row and identify all figures

Question 18

Amblyopia referral indications

Answer 18

• Failure of visual acuity: worse than 20/40 3-5 yrs old or worse than 20/30 in child greater than or equal to 6
• Visual acuity difference of greater than or equal to 2 lines between eyes in passing range
• Abnormal ocular alignment: strabismus
• Abnormal red reflex
• Asymmetry of vision
• Unilateral ptosis, or other lesions that threaten visual axis, such as hemangioma

Question 19

Amblyopia treatment

Answer 19

• Most responsive before age 7, with upper range to be effects 9-10 years
• Elimination of visual obstruction: cataracts, hemangioma
• Correction of refractive error with corrective lenses
• Encourage use of amblyopic eye: patching, corrective lenses, visual blurring, surgery

Question 20

Strabismus

Answer 20

Anomaly of ocular alignment of one or both eyes in any direction
AKA: misalignment of the eyes

Question 21

How is strabismus described?

Answer 21

• Direction of deviation
• Conditions under which presents
• Whether changes with position or gaze

Question 22

What is strabismus related to?

Answer 22

• Family history
• Low birth weight
• Prematurity

Question 23

How is strabismus described?

Answer 23

• Nasal/inward –> eso
• Temporal/outward –> exo
• Upward –> hyper
• Downward –> hypo

Question 24

What should be in strabismus differential?

Answer 24

• Ocular instability of infancy
• Pseudostabismus

Question 25

What is ocular instability of infancy

Answer 25

* Unsteady ocular alignment often sporadically present in newborns until first few months of life * Usually resolves around 3 months of age after child is able to fix and follow

Question 26

What is pseudostrabismus?

Answer 26

* Apparent esotropia in children with wide nasal bridge or large epicanthal folds during first few years of life * Not true strabismus: rather optical illusion in which wide nasal bridge or epicanthal folds cover nasal sclera making eye appear esotropic, particularly when child looks in lateral gaze

Question 27

History in strabismus

Answer 27

* Developmental hx * Family hx * How long present * Head or eye trauma * Genetic or neuromuscular medical issues * Exposure to toxins * Headache, diplopia, or abnormal head posture

Question 28

Physical exams in strabismus

Answer 28

* Corneal light reflex * Cover test * Cover/uncover test * Bruckner Red Reflex

Question 29

Corneal light reflex

Answer 29

* Primary screening technique * Small toy used as accommodation targe with opthalmoscope standing several feet from child * Hold light and toy in same hand and use light to reflect on both eyes at same time * Normal test reveals light refects off same position in each eye

Question 30

Cover test

Answer 30

* Child asked to visually fixate on a target at distance or near * Examiner briefly covers one eye while observing opposite eye for movenet * No movement when covering either eye if normal ocular alignment * Strabismus present if eye that is not occluded with cover test shifts to re-fixate on target when fellow, previously fixating eye covered

Question 31

Cover/uncover test

Answer 31

* Child asked to visually fixate on target at distance or near * Cover placed over one eye for a few seconds and then rapidly removed * Eye that was under cover observed for refixation movement * If strabismus, previously covered eye will shift back into straight-ahead position to re-establish sensory fusion with other eye * Positive test when cover rapidly removed and affected eye deviated and realigns after cover removed to fixate on object

Question 32

Bruckner Red Reflex

Answer 32

* Opthalmoscope with largest diameter light positioned 18-20 inches from child's face and used to visualize both red reflexes at same time * Light positioned just around skin of child's eyes and child should be looking directly at ophthalmoscope * Should be equal in size, shape, color, and hue

Question 33

Complications of strabismus

Answer 33

* Amblyopia * Diplopia * Secondary contracture of extraocular muscles, limiting extraocular motility and binocular vision fields * Psychosocial and vocational consequences

Question 35

Strabismus referral indications

Answer 35

* Constant strabismus at any age * Intermittent strabismus after 6 months of age * Positive corneal light reflex test or cover or cover/uncover * Positive bruckner test * Deviations that change with gaze * Torticollis not explained by muscle spasm * Complaints of eye fatigue * Prematurity/genetic disorder/metabolic disorder * Parenteral concern

Question 36

Treatment of strabismus

Answer 36

* Corrective lenses: address vision impairment caused by amblyopia, refractive error correction with glasses * Patching: refractive error correction with patching * Surgery: recession or resection

Question 37

What is recession surgery?

Answer 37

* Repositioning of muscle insertion posterior to original insertion on sclera which weakens effect on globe position

Question 38

Resection surgery

Answer 38

* Shortening muscle which permits it to act as a passive restraint, effectively increasing its effect on globe position