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  1. #1
    Big fish Guest

    This is an NBME Q-strabismus

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    This is an NBME Q.

    This is an NBME question:
    A newborn has strabismus. Which of the following is the rationale for surgically correcting this problem during early childhood?
    A) Cataract formation is more likely in misaligned eyes
    B) Neither eye will develop normal monocular vision
    C) Normal binocular vision will not develop
    D) Retinal ganglion cells in the temporal hemiretinas will degenerate
    E) Separate representations of each retina will develop on the visual cortex

    I choose C. What's your opinion?

  2. #2
    lyuda_m@yahoo.com is offline Junior Member 510 points
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    It's normal for your baby's eyes to wander or cross now and then during the first month or so of life. A newborn is just getting the hang of making his eyes work together. But if you notice that your baby's eyes seem crossed or misaligned all the time, or if they seem to wander after the first couple of months, the problem could be strabismus (misaligned eyes) or amblyopia (lazy eye). Talk to his doctor, who will probably refer you to an ophthalmologist. Fortunately, these conditions can be successfully treated if detected early.
    If your baby has strabismus and it isn't treated, his brain could start ignoring the input from one of his eyes, eventually causing the vision in the ignored eye to deteriorate. This condition is known as amblyopia or "lazy eye". Depth perception could also be damaged.
    Sometimes strabismus is present at birth. The condition seems to run in families, but can also show up in children with no family history — and when that's the case, it sometimes indicates a more significant vision problem. Those who are farsighted also seem to be at higher risk.
    Strabismus that's a result of farsightedness can usually be corrected with glasses, especially if caught early. Strabismus that persists even when a child wears glasses may require surgical correction. While the lack of coordination between the eyes centers in the brain, it's not possible to operate on the brain to change the alignment of the eyes. Instead, doctors operate on the eye muscles, which are accessible. That's one reason that the surgery isn't 100 percent successful.
    Amblyopia (also called lazy eye) develops when the brain shuts off or suppresses vision in one eye. This can happen if your baby's eyes are misaligned or if he can't see as well with one eye because of nearsightedness, farsightedness, astigmatism, or something that's blocking clear vision in that eye, like a cataract or a drooping eyelid.

    About 3 to 6 percent of children under the age of 6 develop amblyopia. Treatment is most successful before age 5 or 6, although recent research shows that even older children may recover their vision. If ignored, though, amblyopia can result in permanent vision loss.

    How to recognize amblyopia
    Identifying the problem isn't easy because children can get along fine using only one eye. The less-used eye may look perfectly normal, even though your baby isn't using it to see.

    Your child's doctor should routinely test for amblyopia (as well as strabismus) by checking the eyes independently and together. But pediatric ophthalmologist James Ruben, a member of the AAP section on ophthalmology, says it's also a good idea for you to occasionally test the vision in your child's eyes at home.

    Testing for amblyopia at home
    Here's a simple way to get an idea of whether your baby's eyes are both pulling their weight:

    While your baby is interested in an object — a toy bear that you dance in front of him, for example — cover one of his eyes (it helps to have a partner for this). See if he follows the object with his uncovered eye as you move it. Then cover the other eye and see if he follows the object just as well — and as far.

    It's a little tricky to test a baby, who may lose interest or become distracted before your informal test is over. But if one eye seems weaker, try testing it again another time — maybe starting with the other eye first.
    If your baby seems to be able to see better with one eye than the other, schedule an appointment with either your child's doctor for a vision screening test or an ophthalmologist, who can diagnose and treat the problem.
    The first step is to address any underlying problem — by correcting the astigmatism or nearsightedness with glasses or removing a cataract with surgery, for example. Once that's taken care of, the goal is to encourage your child's brain to connect with the weaker eye, eventually improving its ability to see.

    Glasses don't help to improve this eye-brain connection. In fact, one sign of the condition is that your baby's vision is still worse in one eye when he's wearing the correct glasses. That's because glasses work to help the eye focus — like a camera lens — but if the brain isn't communicating well with that eye, there won't be a clear picture.

    Instead, your doctor will probably recommend covering your baby's stronger eye with a patch or using eyedrops once a day to blur the vision in that eye, either of which will force the brain to use the weaker eye. This process could take weeks, months, or even years.


  3. #3
    lyuda_m@yahoo.com is offline Junior Member 510 points
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    I think than correct answer is E.

  4. #4
    Giatros is offline Newbie 510 points
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    Good explanation, thanks

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