Rabu, 08 Oktober 2008

strabismus

Strabismus / Mata juling

What is strabismus ?
= is a condition in which the eyes are not properly aligned with each other.
It typically involves a lack of coordination between the extraocular muscles that prevents bringing the gaze of each eye to the same point in space & preventing proper binocular vision, which may adversely affect depth perception



Classification ?
Depending on the direction that the strabismic eye deviates, The direction of deviation may be assessed. Exotropic is outward (away from the midline) & Esotropic is inwards (towards the nose), or hypotropic (down) & hypertropic (up).


What causes strabismus ?
They include genetics, inappropriate development of the "fusion center" of the brain, problems with the controlled center of the brain, injuries to muscles/ nerves/ other problems involving the muscles/ nerves. Strabismus can caused by a refractive error in one/ both eyes. Ex: high myopia, often leads to atrophy of the choroid & subsequent retinal macular degeneration with loss of control visual acuity & high incidence of strabismus.

What does strabismus cause ?
- The patient will see double because the two eyes are not aimed at the same point (diplopia).
- One of the eyes can turn off (in the brain) to avoid double vision (technically called diplopia). This condition is called suppression.


Diagnosis ?
- Cover test to aid in the dx of strabismus. If the eye being tested is the strabismic eye, then it will fixate on the object after the "straight“ eye is covered, as long as the vision in this eye is good enough. If the "straight“ eye is being tested, there will be no change in fixation, as it is already fixated.














- Hirschberg test a flashlight is shone in the patient's eye. When the patient is looking at the light, a reflection can be seen on the front surface of the pupil. If the eyes are properly aligned with one another, the reflection will be in the same spot of each eye. Therefore, if strabismus is present, the reflection from the light will not be in the same spot of each eye.
















Differential diagnosis ?
Pseudostrabismus is the false appearance of strabismus. It generally occurs in infants & toddlers whose bridge of the nose is wide & flat, causing the appearance of strabismus. With age, the bridge of the child's nose narrows & the folds in the corner of the eyes go away. To detect the difference between pseudostrabismus & strabismus, a Hirschberg test may be used.

Prognosis ?
When strabismus is congenital/ develops in infancy, it can cause amblyopia,in which the brain ignores input from the deviated eye.

Treatment and management ?
- Amblyopia, if minor & detected early, can often be corrected with use of an eyepatch on the dominant eye and/or vision teraphy.
- Advanced strabismus is usually treated with a combination of eyeglasses/ prism, vision therapy & surgery,



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