What is the definition of strabismus

What is the prevalence of strabismus?

Is this more common in neurologically or non-neurologically normal children?

-condition in which the lines of sight of the two eyes are not directed toeard the same fixation point when the patient is fixating and object

-3-5%

-more common in non-neurologically normal children

What types of strabs have been more commonly reported in females?

Which race does ET tend to be found more commonly in?

Which strab is more common in asians?

Overall, does strab show a specific gender, race, or social class preference?

-Duane's syndrome, thyroid myopathy, XT

-whites

-XT

-no

-abnormal binocularity

-amblyopia and amblyopia treatment

-spectacle wear

-EOM sx

-psychosocial

=negative social prejudice and can significantly reduce an applicants ability to obtain or hold employment and can negatively affect ones self image anad interpersonal relationships with others

___% of strabismus commences before what age?

This is know as a "disease of ______"

What is the median stage of onset?

90% before age 5

childhood

29 months

What are the 3 possibilities of and adult with strabismus?

Which is the most ominous sign of the 3?

-childhood onset that was never treated, treated unsuccessfully, residual strabismus, or recurring strabismus

-decompensated heterophoria

-recent onset strabismus

-recent onset strab

Is strabismus hereditary?

What is the incidence range between families?

Therefore, children of parents with strab are more than likely to have strab, just as likely to have strab, or less likely to have strab as those that are born to parents without strab?

-yes

-10-70%

-strab more likley if parents have strab (even higher if both have it)

Heredity of strabismus is _______, which means there are ___ modes of transmission.

Is the strab itself inherited? What may be inherited?

-multifactorial, multiple

-no, rather they underlying cause such as abnoraml AC/A ration, reduced fusional amps, high emetropia, unusual facial configuration, readiness to suppress, reduced stereo, etc

In Helveston's study of parents of strabismic patients, what did they find?

What can be concluded?

-that parents of strab children had 16% greater chance of reduced stereo than parents of those with non-strab children

-reduced stereopsis may represent a sub-threshold effect on gene that cause strab under appropriate conditions

How often can the etiology of strab be reasonably determined?

Many times the etiology is ___ or ___. 

-only about 50% of the time

-vague, presumed

-refractive/optical

-sensory/organic

-anatomic/motor

-innervational

What are some of the optical causes of strabismus?

At what age is this most likely to affect alignment?

Which cause is most associated with ET?

Is myopia associated with XT, usually?

-high amertopia, anisometropia, hyperopia

-younger children

-hyperopia

-no

What is an organic or sensory cause of strab?

What types of disorders might cause this?

What does a severe bilatral interocular disease usually result in?

What is the most common cause of organic/sensory strab?

If a patient experiences an ocular disease as they get older than 5, what is the most likley deviation to develop?

-any disease of the globe, retina, or optic nerve can provoke a strab if it lasts long enough, reaches a stage of irreversibility, or if it is unilateral or asymmetric

-unilateral cataract, unilateral ROP

-amblyopic nystagmus

-unilateral cataract

-XT

What are the motor/anatomic causes of strabismus?

What are some conditions that are commonly associated with strab? Why type of strab?

What % of the last 2 syndromes have strab?

-orbital factors- dimensions of the orbits, spaces between them can be causative for strabismus

-craniofcaial abnormalities- strab is common here

-hypertelorism- favors XT

-small inter pupillary distance and or epicanthal folds favors ET

-Crouzon, Apert syndromes (60-70%)

What is pseduo-XT also know as?

What clinical finding would you expect in this patient?

Which is more common, pseduo ET or pseudo XT?

-ectopic macula

-large positive angle kappa (looks like an XT, but isn't)

-pseduo ET

Pseduo ETs make up what percentage of all presumed ETs?

What is a clinical finding that will help you determine whether it is a true or pseduo ET?

-50%

-is the ET more apparent when the child is viewing to the right or to the left

If the parents say a child has an ET and you do not find it, what should you conclude?

If the parents say that the child has an XT and you cannot find it, what should you conclude?

Of children diagnosed with pseduo-ET before 3 yoa, what percentage will go on to actually have strab?

-you are correct and the parents are wrong

-the parents are correct and you are wrong

-12%

-musculoligamentary factors such as hypoplasia, aplasia, fibrosis, or displacement of EOMs or check ligament

What is a condition of a muscle pulley that can cause a strabismus?

What happens in this condition?

-Brown's syndrome

-SO tendon cannot move freely through the trochlea

What are the innervational causes of strab?

What 3 possibilities would you expect to see with a high AC/A?

-abnormal AC/A

-ortho at distance and ET at near or XT at distance and ortho at near, or XT at distance and ET at near

In a hyperopic child, if the AC/A ratio is abnomally low, will this be more likley to cause or not cause a strab?

In a hyperopic child with a high or normal AC/A ratio, will this be more likley to cause or prevent a strab?

-prevent a strab

-cause a strab

If you see a child that is highly hyperopic and is ortho, what would you presume?

What about a child with a small amount of hyperopia that is ET?

-they have an abnormally low AC/A ratio

-abnormally high AC/A ratio

What is the most likely innervational cause in infantile ET?

What is this caused by?

What happens to many infantile ETs and other strabs under general anesthesia?

-innately weak or absent fusion

-excessive or insufficient innervation to EOMs

-they become ortho

What questions do you want to ask in the case of innervational strabs?

What syndrome is 10x more likely to have strab compared to normal children?

Which strab is more likely here?

-is the brain normal?

-Down's syndrome

-Esotropia

What percentage of children with cerebral palsy have strab?

What kind of strab? What does this mean?

What is the ___% of children with this kind of strab?

This is supposedly ____ for CP?

-44%

-dyskinetic strab- variable fluctuation between ET and XT that is independent of accommodation, changes in fixation, direction of gaze, or visual attention status

-12-23%

-pathognomonic

What happens in spasm of near reflex?

This is an ___ problem?

How migh we cause this?

-variable ET, pupillary miosis, AS, limited motility

-integrative problem

-pharmacologically induced with mydriatics

A blindspot ET is an ____ anomaly.

What is a blindspot ET?

Do these patients have normal fusion potential?

What type of strab do you expect to see?

Will you see suppression or ARC?

What happens if they are presented with undercorrecting prism?

-innervational

-when the ON is used binocularly

-yes, despite early onset

-25-35 PD ET at distance and near

-no, these are prevented since the extra-foveal images coincides with the blindspot

-they have diplopia

What are the 2 subdivisions of the nature of strabismus?

What do they mean?

-comitant- the angle of the strabismus is the same (within 5 PD) in all positions of gaze, or with each eye fixating in turn

-incomitant- angle of strabismus changes by more than 5 PD in the positions of gaze, or with each eye fixating in turn

What are the different directions a strab may have?

-horizontal- ET, XT

-vertical- hyper T, hypo T (according to fixating eye)

-cyclotorsioanl- rotation around the antero-posterior axis

What angle is a small strab?

Moderate strab?

Large strab?

- >/= 10 PD

-11 PD- 30PD

- > 30 PD

What are the subdivisions of laterality?

Which is more likley amblyogenic?

-monocular or unilateral

-alternating

-monocular/unilateral

-constant

-variable

-intermittent

-relative/periodic

If there is similar magnitude in the strab between distance and near (within 10 PD), what is presumed?

If there is dissimilar magnitude at distance and near (> 10 PD), what is presumed?

-a normal AC/A ratio

-an abnormal AC/A ratio

What are the 2 subdivisions of age of onset?

What are the ages of onset for both?

-congenital (infantile)- 6mo or younger

-acquired- onset after 6 mo