Strabismus Flashcards
This occurs when the visual axes of both eyes do not intersect at fixation
Strabismus
Consequences of strabismus
- risk of amblyopia in the deviated eye, reduced stereopsis, reduced fusion, suppression, and change of ARC
- symptoms: diplopia, blur, HA, anomalous head positioning, asthenopia
- there is also risk of injury to the better seeing/aligned eye
Prevalence of strabismus
-strabismus prevalence in the general population is 2-6%
In young children, the prevalence is about 2-3%
Risk factors for eso-tropia in children 6-72 months (BPEDS/MEPEDS)
As hyperopia goes up, so does the odds and chance of esotropia
2-3D: 6.3 odds
3-4D: 23x
4-5D: 59x
>5D: 122x
> 5D almost guarneteded to have esotropia
Relationship between refractive SE and adjusted prevalence of esotropia in children 6-72 months: BPEDS/MEPEDS
SE refractive error in less hyperopic eye from 2D on wards, has a large increase in prevelance of esotropia
Anisometropia >1D and esotropia
2x chance
Age in months and risk of esoptrioa
48-59 months old: 8x chance
60-72 months: 9x chance
Maternal smoking during pregnancy and odds of esotropia in kid
2x
Gestational age <33 weeks and chance of esotropia
4.43x chance of esotropia
Risk factors for exotropia in kids 6-72 months: astigmatism in eye with lower amount
1.50 to <2.50: 2.5x
> 2.50D: 5.88x
Maternal smoking during pregnancy and exotropia
2.88X
Gestational age <33 weeks and risk of exotropia
2.48X
Risk factors for exotropia: gender
Female: 1.62X
Family Hx and risk of exotropia in 6-72 months
Increases odds of XT if positive family Hx
Etiology of strabismus
Mechanical restrictions: abnormality of the EOMs; tumor metastasis; trauma etc
Uncorrected refractive error-esotropia (in hyperopes)
Other neuro abnormalities: innervation anmoalies resulting in paresis and paralysis
Neuro defects: brith injuries, cerebral palsy, developmental/special needs, ROP
Breainstem abnormaliteis or abnormalities along the visual pathway
Assault during gestation-smoking, alcohol
Genetics- strab of parent or sibling
Time of onset of strab: infantile
Onset at birth or during the 1st 6 months of life
Congenital is born with it
Time of onset of strab: acquired
Strabismus that developed after 6 months
Acquired strab deviations are
- acute (trauma, tumor, infection, inflamamtion, vascular disease)
- longstanding
- consecutive
Frequency of strab
Constant
Intermittent
Laterality of strabismus
Right
Left
Alternating
Direction of strab
Esotropia Exotropia Hypertropia Hypotropia Cyclotropia
Location of strab
Distance and near
Magnitude of strab
Measured in PD at D and N
Comitnancy of strab
Comitant: deviation same in all positions of gaze
Non comitant: deviation different in different positions of gaze.
Due to over action or under action of one or multiple muscles from innervation problems (paralytic) or mechanical restrictions
Onset of strab
Infantile (at birth or during 1st 6monthjs of life)
Acquired
Manifest deviation not properly controlled by fusional vergences
Esotropia
Deviations from neuromuscular abnormaliteis can be from ___ in esotropia
Innervation, anatomical, mechanical, refractive, accommodative, or genetic problems
Accomodative acquired
Refractive accommodative; non refractive accommodative; mixed accommodative
Secondary esotropia
Sensory (due to mac scar)
Consecutive (because of surgery)
Exodeviation
- manifest is tropia
- deviations are signs of neuromuscular abnormaliteis that can result from innervation, anatomical, mechanical, refractive, accommodative or genetic problems
Interestingly, prevalence varies by ethnic groups
Types of exotropia
Infantile
Acquired
Secondary
Acquired exotropia
Intermittent
Acute
Mechanical/non comitant
Secondary exotropia
Sensory
Consecutive
Exam overview for strab: detailed Hx
detailed Hx
- eye turn: which eye, onset, nature of onset, frequency and size
- eye Turn-presence/absence of diplopia, or associated symptoms/signs
- med Hx-neuro, developmental, or systemic problems
- brith Hx (prematurity and low birth Wt)
- fam Hx of strab
- previous treatments
- medications
- development and learning concerns
Exam for strab
- VA;age appropriate
- CT- presence, frequency and mag of deviations
- ocular motility-EOMS, saccades, pursuits
- pupils
- accomodation- amp and response
- BV function (sensory status: stereopsis, W4D, fixation)
- cycloplegic refraction
- anterior and posterior segment evaluation
Strab management overview
- correction or refractive error
- added lenses (bifocal, plus or minus)
- prism: if already developed normal retinal correspondence and BV
- occlusion: for amblyopia, suppression, or vergence ranges
- VT-for amblyopia, suppression, or vergence ranges
- pharm-Botox
- surgery-especially for large angle
Prism and retinal correspondence
Only for NRC
You will break it for ARC
