Pediatric Ophthalmology Flashcards
Acuity of a newborn is usually ____ and only ____ until the age of 3 and reaches adult level by 3 - 5 years of age
- 20/200 - 20/400
- 20/60
what two vision function develop between ages of 3 and 7 months
Stereopsis (perception of depth)
binocular (both eyes)
Infants should be able to follow an object by what age?
3 months of age
A 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
Amblyopia
MCC of pediatric visual impairment,
A functional reduction in the visual acuity of an eye
Amblyopia
pathophys of Amblyopia
Abnormal vision development in infancy/childhood
- Unilateral or bilateral
- brain receives a poor image from the eye and thus does not “learn to see well”
- Vision loss occurs b/c nerve pathways between brain and eye are not properly stimulated
RF amblyopia
- prematurity
- FHx of 1st degree relative
- small size for gestational age
- neurodevelopmental delay
3 classifications of amblyopia
- strabismus
- refractive
- deprivational
Misalignment of the visual axes of the two eyes
which type of mablyopia
Strabismus
One or both eyes having a refractive error causing an imbalance between the eyes
which type of amblyopia
refractive
Obstruction by a cataract or complete ptosis prevents formation of a formed retina
what type of amblyopia
Deprivational
One eye may turn in, out, up, or down
Described according to the direction of the deviation
this presentation is for what dx?
Strabismic Amblyopia
pathophys of Strabismic Amblyopia
- brain ignores, or “turns off” eye that is not straight and vision drops in that eye
- Occurs because foveas of the two eyes are presented with two different and unfusable images.
- The visual cortex suppresses the image from one eye in order to avoid having diplopia; long-term suppression of one eye results in strabismic amblyopia
refractive amblyopia MC occurs as a result of ?
asymmetric refractive error (anisometropia: glasses strength)
pathophys refractive amblyopia
- Both foveas are presented with different image clarity d/t unequal uncorrected refractive errors; one eye is not focused on the fovea at the same time as the other
- The brain does not learn how to see well from the eye that has a great need for glasses
refractive amblyopia occurs MC in what other vision condition
hyperopic
Why is refractive ambolyopia detected at an older age than strabismic amblyopia?
- refractive amblyopia lack obvious external abnormalities and visual functioning appears nml because they see well with the fellow eye
- Often dx at first vision screening when they are old enough to identify letters or figures (ages 4 or 5)
- Least common form of amblyopia, but most severe
- It results from vision deprivation, typically a result of interruption of the visual axis or severe **distortion of the foveal image. **
Deprivational Amblyopia
what other severe conditions may cause Deprivational Amblyopia
Congenital cataracts, ptosis, congenital corneal opacities, vitreous hemorrhage, and severe refractive errors
Deprivational amblyopia in infancy results in _____ if not treated urgently
permanent visual impairment
amblyopia evaluation in pre-verbal child
- Fixation reflex: amblyopia will rarely maintain fixation with amblyopic eye when both eyes uncovered
- occlusion objection test: mod-severe - will become more irritable when the other eye with better vision is occluded.
testing involves moving a visual target to and from the child’s visual space, each eye being tested by occluding the fellow eye
Fixation reflex
Involves monitoring the child’s response to alternate occlusion of the eyes. Children with equal vision respond equally, or not at all to occlusion of either eye.
occlusion objection test
amblyopia evaluation in verbal child 3y and older?
- VA - Allen or Snellen charts
- Cover
- Cover/Uncover
what line is 20/20 on allen/snellen charts?
7
Single best screening device in verbal children
Attempt at 3 years of age and older
visual acuity
Snellen chart measured at ___ ft and marked off
20
Begin with 20/40 and if child misses two figures in a row, ask the child to go up a row and identify all figures
Amblyopia Referral Indications (6)
- failed VA - worse than 20/40 (3-5y) or 20/30 (6y or older)
- abnml red reflex
- VA difference - Difference of greater than or equal to 2 lines between eyes in passing range
- asymmetry of vision
- abnml ocular alignment - Strabismus
- unilateral ptosis - Or other lesions that threaten visual axis, such as hemangioma
Amblyopia Treatment? When is intervention the most effective?
- Most responsive when initiated before age 7, with upper range to be effective is 9-10 yrs
- Elimination of any visual obstruction - Cataracts, Hemangioma
- Correct any refractive error - Corrective lenses
- use amblyopic eye - Patching, Corrective lenses, Visual blurring, Surgery
4 Strabismus Descriptions
- Eso - nasal/inward
- Exo - temporal/outward
- hyper - upward
- hypo - downward
Tropia: deviation of the eyes
Unsteady ocular alignment often sporadically present in newborns until the first few months of life
Usually resolves around 3 months of age after child is able to fix and follow
which strabismus ddx?
Ocular Instability of Infancy
- The apparent esotropia with a wide nasal bridge and/or large epicanthal folds during the first few years of life
- Not true strabismus; rather an optical illusion in which the wide nasal bridge or epicanthal folds cover nasal sclera making the eye appear esotropic, particularly when the child looks in lateral gaze
which strabismus ddx?
Pseudostrabismus
assoc sx of Pseudostrabismus
- Headache
- Diplopia
- Abnormal head posture
PE tests for strabismus
- corneal light reflex
- cover test
- cover/uncover test
- bruckner red reflex
Primary screening technique
* Accommodation target using a small toy used w/ ophthalmoscope light standing several feet away.
* Hold light and toy in same hand and use the light to reflect on both eyes at the same time
what test?
what is a normal finding?
Corneal Light Reflex
the light reflects off the same position on each eye
how to perform cover test?
findings?
strabismus
- child fixates on target at distance or near
- examiner briefly covers one eye while observing opposite eye for movement
- No movement when covering either eye = normal
- eye not occluded shifts to re-fixate on the target when the fellow, previously fixating eye is covered = strabismus
how to perform cover/uncover test? findings?
- Child fixates on target at distance or near. A cover is placed over one eye for a few seconds and then it is rapidly removed.
- The eye that was under the cover is observed for refixation movement
strabismus: previously covered eye will shift back into straight-ahead position; when cover is rapidly removed and affected eye is deviated.
how to perform Bruckner Red reflex
- Positioned 18-20 in from child’s face, ophthalmoscope used to visualize both red reflexes at same time
- light should be positioned just around the skin of the child’s eyes and the child should be looking directly at the ophthalmoscope. The red reflexes should be equal in size, shape, color, and hue
Strabismus - Complications
- Amblyopia
- Diplopia
- Secondary contracture of extraocular muscles, limiting extraocular motility and binocular vision fields
- Psychosocial and vocational consequences
Strabismus - Referral Indications
- Constant strabismus at any age
- Intermittent strabismus >6mo of age
- (+) ocular tests
- Deviations that change with gaze
- Torticollis not explained by muscle spasm (can be compensatory mechanism to achieve optimal vision in strabismus)
- Complaints of eye fatigue
- Prematurity / genetic disorder / metabolic dz
- Parental concern
Strabismus - Treatment
-
Corrective lenses
- Address vision impairment caused by amblyopia
- Refractive error correction with glasses -
Patching
- Refractive error correction with patching -
Surgery
- Recession: Extraocular muscle recession involves repositioning of muscle insertion posterior to the original insertion on sclera = weakens this effect on globe position
- Resection: shortening the muscle = passive restraint = increasing its effect on globe position
