Why is their little girl wearing an eyepatch?

Is ANNA NICOLE SMITH's little girl losing her sight? Only ET has the truth behind why LARRY BIRKHEAD and Anna's baby is wearing an eyepatch!

"She has strabismus, which is a turning in of one of her eyes, and it's something that we've been looking out for for a while," Larry tells our own MARK STEINES in an exclusive interview. "I've been taking her to the doctors and ... Anna had taken Dannielynn to the doctor [in the Bahamas] to see about it when she was just a few months old."

Common in about five percent of children, the eye condition is perhaps better known as "cross-eyed" and it is something that cannot be outgrown and must be treated. An eyepatch is used to cover the strong eye in an effort to strengthen the weak one.

"I got her a little pirate doll to show her that people wear patches, and it's okay," says Larry, "and daddy wears a patch if he has to to show her it's okay. I've been really aggressive with the patch as much as I can be. At first she was really open to it and it didn't really bother her. Now, she's gotten a little smart because she can pull it off, so it's a little bit harder for me to patch her."

But if the eyepatch doesn't work, or if using medicated eyedrops to dilate the pupil fails, little Dannielynn may face surgery.

"I'm going to do everything to make sure that it's corrected," says Larry, "but having lost Anna and [her son] DANIEL and my dad -- my dad just came out of a simple surgery and he died -- it's just tough for me to think about surgeries with [Dannielynn]."

And Larry staunchly defends any suggestion in the tabloids and on Web blogs that Dannielynn's condition has anything to do with methadone or any medications Anna may have taken during her pregnancy.

"All of the opinions that I had [from doctors], every one of them said that it's very, very unlikely, because no one knows one-hundred percent what causes [strabismus]," says Larry. "But I point-blank ask every single doctor, 'Could any medications that Anna was on have caused this?' and they said that it's more likely that a genetic reason could have caused it."