Prism and Strabismus

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Strabismus is a disorder in which the two eyes do

not line up in the same direction, and therefore do

not look at the same object at the same time. The

condition is more commonly known as "crossedeyes.³

One eye may look straight ahead, while the other

eye turns inward, outward, upward, or downward.



Genetics

Inappropriate development of the "fusion center"

of the brain.

Problems with the controlled center of the brain. Injuries to muscles or nerves or other problems

involving the muscles or nerves.



` Eyes that do not look in the same direction at the sametime.

` Eyes that do not move together. (The direction that theaffected eye moves depends on the type of strabismus thechild has.)

` Squinting or closing one eye in bright sunlight.` Tilting or turning the head to look at an object.` Bumping into things (strabismus limits depth perception).Complaints of the patient:` Blurred vision.

` Tired eyes.` Sensitivity to light.` Double vision.





` Esotropia. The most common form of childhood

strabismus is "crossed eyes," or esotropia, in

which one eye turns inward, toward the nose,

instead of looking straight ahead.E

sotropia oftenappears early, in infants or very young children.



` Exotropia. Exotropia, commonly called walleye, is

a form of strabismus in which one eye turns

outward, toward the temple. Symptoms of exotropia usually begin between the ages of 1 and

6 years

` Hypertropia. Also called vertical deviation,

hypertropia is a form of strabismus in which one

eye turns upward, toward the eyebrow. It is a far

less common form of strabismus.



Constant- When an eye deviates all of the time,

Strabismus is classified as constant

Intermittent- If, on the other hand, an eye

deviates only some of the time, Strabismus isclassified as intermittent. Intermittent cases of

Strabismus usually result from some other

physical condition, such as sickness or stress.



Unilateral Strabismus- If only one eye converges

or diverge.

Bilateral Strabismus- If both are eyes converge

or diverge, at the same time.Alternating Strabismus- If convergence or

divergence alternates between the eyes, such that

one eye is able to focus on an object while the

opposite eye is askew.



` Congenital

When strabismus is developed during infancy.

Congenital Strabismus may develop

Amblyopia or Lazy eye Amblyopia is anaturally occurring condition in which the brain

ignores any input from a deviated eye.

Amblyopia in infancy causes problems in the

ability to perceive depth.



` Acquired

Strabismus that develops in adults. AcquiredStrabismus in an adult, who otherwise had proper

alignment of the eyes before the onset, is likely to

cause double vision, which also known as diplopia.

typically caused by injury to the eye orbit or injuries to

the brain, such as with a stroke or head injury. Loss of

vision from Acquired Strabismus usually results in a

gradual development of an exotropia condition, rather

than Amblyopia.



` Suppress one eye

` Head Tilting` Face turning

` Both Face turning and Head tilting





` Glasses-If the eyes are only slightly misaligned, wearing

glasses can sometimes correct strabismus.-Some children may need to wear bifocals or special

lenses called prisms.

` P atches- This is primarily a treatment for amblyopia (lazy eye).-The stronger eye is covered with a patch to force the

child to use the weaker eye. Excessive use of a patch cancause amblyopia in the initially stronger eye



` Atropine- used instead of patching to help treat poor vision in one eye by blurring vision in the good eyebeyond that of the weaker eye and forcing the child touse the weaker eye.

` M iotics ± (echothiophate iodide) affect muscles in theeye that control the pupil and the eye¶s ability to focus.

` Botulinum toxin ± (botox) a drug that temporarilyprevents contraction of a muscle for several months at

a time. It causes the muscle to relax, which allows theopposing muscle to change the eye¶s position.



` Recession is a weakening of eye muscles. Theprocedure involves detaching one of the six muscles attached to the eye and a reattachmentof that muscle further to the back of the eye.

` Resection is a strengthening of eye muscles. Thesurgical procedure involves detaching one of theeye muscles, removing a portion of the musclefrom the distal end of the muscle and reattachingthe muscle to the eye. As a result of surgery, most

patients are expected to experience some form of straitening that positions their eyes in the forwarddirection.



` is a transparent optical element with flat,polished surfaces that refract light. The exact

angles between the surfaces depend on the

application.



` Prism An eye looking through a prism will be place

towards the apex.

If the patient is esotropia

: Base±in Prism

If the patient is Exophoria

:Base-out Prism

If the patient is Hypertropia:Base-Up Prism

If the patient is Hypotropia

:Base-down prism



` If the strabismic patient already developed

Anomalous Retinal Correspondents, We

should not prescribe prisms

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Prism and Strabismus