Sudden onset of strabismus

I first noticed my son's left eye turning inward when he was 19 months old.  At 22 months I took him to two different optomologists for an evaluation.  Because he did not have a vision problem, we patched his eyes for several hours a day for approximately six months.  He had surgery when 28 months old.  He is now 32 months old and, so far, he seems to be doing very well.
Last week, my 13 month old daughter suddenly appeared cross-eyed.  I exam her eyes nearly every day and look closesly at every photograph.  I have enough video and photographs to prove that this just happened!  Her eyes were perfect until 8 days ago.  The first five days there was limited deviation.  Most Xmas pictures are perfect.  However, on Sunday, 12/28, her eye was severely deviated nearly 100% of the time.  And it hasn't gone back.  So... yesterday I got her in with a pediatric opthomoligist to ensure there wasn't brain/nerve damage.  I was told she seems to have the same thing her brother had; however, she is slightly farsighted.

QUESTIONS:  How could this have come on so quickly and be so severe?  If the brain just stopped sending the right signals to her eyes, can this happen again after surgery?
Also, after surgery, does the brain re-learn binocular and 3D vision?

[Flavius G Pernoud III, MD]

It does run in families. Yes it can come on suddenly. Many times mom or dad doesn't notice it until Aunt Millie comes over and asks why the childs eyes are crossed. The brain can re-learn binocular vision but the sooner the eyes are straightened the better. The abnormal position quickly teaches the brain to ignore the image from the one eye.

[Oliviaparker]

Yes, it definitely runs in families. I was disgnosed with strabismus at age two, and my worst fear was that I would pass it along to my children. I once though I noticed some abnomalities with my older daughter and took her to the doctor. They told me she was fine and it was my paranoia getting the best of me. So when I though I noticed my younger daughter's eye turning in, I wanted to believe that it was imagination again, but it very soon became clear that it wasn't. I too was really puzzled as I was going back and looking at fairly recent pictures because it seems to have come on rather suddenly. In looking at pictures from only a few months ago, her eyes look perfectly straight. Now her right eye turns in, and it seems to be getting worse every day.

[John C Hagan III, MD, FACS, FAAO]

Be sure your child is under the care of a pediatric ophthalmologist.

Incidence of eye muscle problems in general population: 2%
Incidence of eye problems in blood relatives of someone with an eye muscle problems: 20%

JCH MD