WASHINGTON, March 28 Some 2.3 million U.S. preschoolers have an eye disorder that could result in permanent vision loss if not treated, says the National Eye Institute.The institute estimates only one in five preschoolers get their vision screened.About 300,000 to 750,000 children 3 to 5 have amblyopia, or lazy eye. The condition is often undetected because the stronger eye overcompensates, according to the institute.Early detection is essential to restoring sight for these children, says pediatric ophthalmologist Dr. Michael Repka of the American Academy of Ophthalmology and Johns Hopkins University in Baltimore.Treatment includes glasses, patches and a kind of eye drop, and more than 80 percent of patients are restored to the normal range of vision through one or more of the three treatments, according to Repka.Copyright 2007 by UPI