maintaining healthy vision plays a critical role in a child 's overall success at school . early detection of vision problems in children is essential , as failure to identify and implement an effective treatment in a time sensitive manner can result in a permanent reduction in visual acuity that could have been otherwise prevented . comprehensive eye examinations that include a complete and detailed inspection of the visual pathway and eye anatomy are indispensable for individuals with known or suspected problems , risk factors , or positive family history of eye disease . however , in comparison , routine pediatric vision screenings are cost - effective and practical and can be a highly accurate means of quickly identifying children that should be referred to have a more detailed examination by an eye care specialist trained at managing pediatric ophthalmic conditions [ 2 , 3 ] . ( where healthy eyes and ears lead to success ) kindergarten readiness program is a mobile vision and hearing screening initiative for preschools in the greater richmond , virginia area . the program was created and is sustained by the medarva healthcare foundation and prevent blindness mid - atlantic , is offered at no cost to the children or schools involved , and specifically targets 4-year - old preschool programs . this target age allows for an effective treatment strategy to be implemented if necessary prior to school entry [ 3 , 4 ] . amblyopia , defined as a decreased vision caused by poorly developed visual areas of the brain from inadequate early visual experience , occurs in 1% to 4% of children ; risk factors for this eye disorder can be detected in a matter of seconds with a high accuracy during a vision screening examination using photoscreening technology [ 57 ] . in the united states , there is a high variability in vision screening recommendations since each state mandates their own policy . furthermore , there are currently a paucity of reports presenting information from a large - scale mobile vision screening program using photoscreening technology that targets 4-year - olds . program that have been collected for the past four years of the program 's existence , with an emphasis on the most current screening year conducted . the w.h.e.e.l.s . program began delivering vision screenings in 2010 using the plusoptix s09 vision screener ( plusoptix inc . , nuremburg , germany ) . in 2013 for year 4 of the screening program , the s09 model was replaced with the newer plusoptix s12 hand - held photoscreener ( plusoptix inc . , nuremburg , germany ) . there is also a hearing screening component of the program that utilizes the welch allyn oae hearing screener ( welch allyn inc . , skaneateles falls , ny ) and an educational component provided for the children , parents , and teachers ; the related diagnostic outcomes of the hearing screening and the details of the educational curriculum will be addressed in a later manuscript . trained and credentialed w.h.e.e.l.s . program staff members conduct the noninvasive screenings 4 days per week , for 9 months each year . the population of the children represented varies from head start programs , virginia preschool initiative programs , child day care centers , and public schools and private preschools within the richmond metropolitan area . prior to each screening visit permission is obtained from the parents or guardian , and directly after the completion of the screening a printed certificate showing the screening results and a letter of explanation are provided to the parents , as well as referral documentation recommending that the child seek care from a pediatric eye doctor if the child does not pass the screening . the diagnostic measures for the children screened are as follows : anisometropia , astigmatism , myopia , hyperopia , anisocoria , and gaze asymmetry . the w.h.e.e.l.s . program was initiated in september of 2010 and has provided vision screenings in the greater richmond , virginia area , each of the four years of the program . as of march of 2014 , 15,075 preschoolers have been offered a free vision screening from 50 public school locations and 63 private pre - k programs . a total of 12,402 children have received a vision screening by the program , which represents 82% of screenings offered ; see table 2 . the remaining 18% of children that did not receive a screening after the offer and consent were sent to the parents were either opt - outs , absent during the screening visit , or due to no response from the parent giving permission for the screening to take place . a total of 3,018 children , or 24% of children screened throughout the four years , have had an abnormal parameter on the screening . parents receive a screening certificate reporting the results of their child 's vision screening rather pass or fail , which also contains information about the screening process and the importance of healthy vision in children especially as it pertains to their performance in the classroom . additionally , the parents or guardians of the children that represented a failed exam were subsequently provided with referral documentation recommending that the child seek care from a pediatric eye care specialist . all caretakers are also provided with a postcard mailing requesting self - reporting as to whether their child has received follow - up care as a result of their screening . the percentage of children that reported receiving a comprehensive eye examination after failing a screening exam from the program is 30% , even with aggressive reporting measures in place that includes preschool director reporting , returned referrals from medical professionals , and parent self - reporting on returned postcards as previously noted . poor reported follow - up rates following failed vision screenings have been previously recognized [ 8 , 9 ] . it is possible that a higher percentage of children referred due to a failed vision screening followed up appropriately with an eye care specialist without reporting the follow - up visit . nevertheless , low reported follow - up rates raise concerns that the child referred is at risk for not receiving the appropriate care in a timely manner and also create limitations in documenting outcomes from the children that failed the vision screening . effective strategies to improve upon low follow - up rates could be further strengthening communication efforts to unaware parents , highlighting the critical importance of following up in a timely manner , and facilitating support to families to find and reach the appropriate eye care specialist . refractive outcomes determined by the plusoptix s12 hand - held photoscreener ( plusoptix inc . , nuremburg , germany ) in the children that passed the screening were compared to those that failed ; see table 3 . this screening year represented 2945 children that were screened , and 818 , or 28% of the children that failed the screening , were recommended for referral ; see table 2 . the children represented in the failed group on average had more diopters in sphere and cylinder in both eyes when compared with the children in the passed group . the screening year 4 pupil and gaze asymmetry characteristics in the children that passed the screening compared to those that failed can be seen in table 4 . the pupil size for both eyes and the pupillary distance were similar for both the passed group and the failed group . the gaze asymmetry measurement was slightly higher in the failed group on average when compared with the children in the passed group . significant refractive errors outside the normal parameters were more frequently the cause for a failed exam compared with pupil or gaze asymmetry errors . program using the plusoptix photoscreening technology that has been collected since the program was initiated in 2010 . the program has identified a high number of preschoolers with significant amblyopic risk factors each screening year that were previously undetected . identifying the risk factors for amblyopia , the leading cause of impairment in vision in children , includes using referral parameters within the photoscreening device to recognize significant anisometropia , astigmatism , myopia , hyperopia , anisocoria , or gaze asymmetry abnormalities [ 1113 ] . vision screening regulations differ in each state in the united states since there is not currently a federally mandated uniform vision screening law . program was developed as a kindergarten readiness specific initiative as there was no standardized method for screening preschool children in place in virginia . in general , most routine vision screening evaluations are performed at the child 's well - child check - up visits or by a licensed healthcare professional at the child 's school , although there are perceived barriers that may limit achieving an optimal referral catch rate [ 14 , 15 ] . photoscreening provides an objective and reliable method to identify young children with visual characteristics that are outside the normal parameters [ 16 , 17 ] . although follow - up reporting outcomes from children who fail a vision screening examination may be challenging to achieve at high rates , having a mobile vision screening program that uses photoscreening technology in screenings targeting children prior to school entry is an efficient , cost - effective , and noninvasive way to assist in identifying a significant number of children that need to be referred to an eye care specialist [ 13 , 18 ] .
objective . to report the results of the w.h.e.e.l.s . 
 prevent blindness mid - atlantic vision screening program that targets preschoolers using the plusoptix photoscreener ( plusoptix inc . 
 , nuremburg , germany ) . 
 methods . trained program staff members conducted vision screenings at up to 113 preschool programs in the richmond metropolitan area for four consecutive years ; 
 a cross - sectional analysis was performed . 
 results and discussion . from september 2010 to march 2014 , 15,075 preschoolers have been offered a free vision screening ; 12,402 ( 82% ) have been screened . 
 a total of 3,018 ( 24% ) have failed the screening and were recommended to follow up with an eye care specialist for a comprehensive examination ; only 30% reported complying . 
 significant refractive errors were more frequently the cause for a failed screening . conclusions . the w.h.e.e.l.s . 
 program has identified a high number of preschoolers with significant amblyopic risk factors that were previously unknown to be present . 
 undesirably low follow - up reporting outcomes from children who fail a vision screening examination were consistent with other reports . 
 nevertheless , having a mobile vision screening program that uses photoscreening technology in targeting children prior to school entry is an efficient and cost - effective way to detect vision disorders in a timely manner .