Both strabismus and amblyopia are more common in older children than younger children, suggests a study of more than 6,000 children in the Los Angeles area. And, researchers note, many of the children in the study had previously gone undiagnosed.

These results, published in the online edition of Ophthalmology, are from the first phase of the Multi-Ethnic Pediatric Eye Disease Study (MEPEDS), conducted by researchers from the University of Southern California Keck School of Medicine.

Researchers examined 3,007 Hispanic children and 3,007 black children in Los Angeles. The children ranged from 6 months to 6 years of age. Overall, the prevalence of strabismus in black children was 2.5%, while its prevalence in Hispanic children measured 2.4%. Amblyopia was found in 2.6% of Hispanic children but only in 1.5% of black childrena statistically significant difference.

The prevalence of both strabismus and amblyopia trended upward equally until age 3 in both study cohorts. At this point, amblyopia prevalence leveled off, while the prevalence of strabismus continued to increase with age.

This is the first evaluation of strabismus and amblyopia in these two ethnic groups, says principal investigator Rohit Varma, M.D. What was most surprising about our findings was that the vast majority of children whom we diagnosed with either strabismus or amblyopia had been previously undiagnosed and hadnt received any care. Both of these disorders can be detected by age 3, so this points to a crucial need for early screening and intervention programs that could prevent lifelong visual impairments.

This large-scale, multi-phase study began in January 2004, based on both location and race. All phases of the MEPEDS study will have been completed by 2011.

Multi-Ethnic Pediatric Eye Disease Study Group. Prevalence of amblyopia and strabismus in African American and Hispanic children ages 6 to 72 months: the Multi-Ethnic Pediatric Eye Disease Study. Ophthalmology 2007 Oct 20 [Epub ahead of print].