Early detection of significant vision problems in children is a high priority for pediatricians and school nurses. Routine vision screening is a necessary part of that detection and has traditionally involved acuity charts. However, photoscreening in which "red eye" is elicited to show whether each eye is focusing may outperform routine acuity testing in pediatric offices and schools. This study compares portable acuity testing with photoscreening of preschoolers, kindergarteners, and 1st-graders in 21 elementary schools. School nurses performed enhanced patched acuity testing and two types of photoscreening in a portable tent. Nearly 1,700 children were screened during spring semester 2004, and 14% had confirmatory exams by community eye care professionals. The results indicate that one form of photoscreening using a Gateway DV-S20 digital camera is significantly more sensitive to children with significant vision problems, as well as being the most cost effective (85% specificity and only $0.11 per child). This suggests that the adaptation of photoscreening into a routine vision screening protocol would be beneficial for efficiently detecting vision problems that could lead to amblyopia. (Contains 2 tables and 3 figures.)