This retrospective study reports the results of photoscreening to detect amblyopic risk factors in a large cohort of children in one statewide program. The study includes 147,809 children screened with the MTIPhotoScreener in Iowa over a nine-year period and reports on the effect of adding a follow-up coordinator to the program. Follow-up in children with abnormal photoscreen results referred for further vision testing was as low as 36.1 percent before this addition but remained above 80 percent afterward. Taking into account only those children whose follow-up examinations were adequate-adequate exams included a cycloplegic refraction (87 percent of follow-up examinations)-the positive predictive value of the MTIPhotoScreener was 94.2 percent. Children were referred if they had one of the following amblyopia risk factors: strabismus, media opacity, astigmatism ≥ 1.5D or ≥ 1.25 D if oblique, hyperopia ≥ 3.5 D, myopia ≥ 3D or anisometropia ≥ 1 D. The cost of screening was $9 per child, taking into account the program's operating budget, including salaries and associated costs.
An editorial in the same journal issue says that the study adds to the evidence that objective screening technologies are highly effective at detecting the most common causes of visual impairment in children. The editorial's author says that despite the overwhelming body of evidence demonstrating that amblyopia can be treated once detected, there is no consensus regarding the implementation of vision screening policies to identify children who are at risk. He adds that the resulting poor penetrance of preschool vision screening has caused the public and the optometry lobby to respond with mandatory eye examination legislation in several states, despite the lack of evidence for its effectiveness, its relatively high cost and resultant over-prescription of spectacles and published evidence that screening is more cost-effective.
The editorial's author says that vision screening is not more widely used in part because professional organizations have been slow to embrace the technology. He says that the failure of the Academy, the American Academy of Pediatrics and the American Association for Pediatric Ophthalmology & Strabismus to update position statements on the technology has been interpreted by payors and others as a lack of support. He concludes that ophthalmology should embrace the effectiveness of technologies used to conduct vision screening in preschoolers in the current study and other similar studies.
In the current study, screening photographs were taken by volunteers from local Lions clubs at 9746 sites. The photographs were sent to the University of Iowa for interpretation. Children with abnormal photoscreen results were referred to local eye care professionals, who preformed comprehensive eye evaluations and forwarded the results to the Iowa KidSight program.
The program referred 6247 children (4.2 percent) because of abnormal photoscreen results. Between 2000 and 2003, the follow-up rate ranged from 36.1 percent to 53.71 percent. In an attempt to improve this rate, changes were made to the program, including the hiring of a paid, part-time follow-up coordinator in October 2003. In 2004, the follow-up rate improved to 89.28 percent. The program follow-up rate after the addition of the follow-up coordinator was 81.3 percent.
Although the positive predictive value of photoscreening was high, the authors acknowledge that they do not know what proportion of children with the targeted amblyopia risk factors were missed by photoscreening. In addition, although the levels of refractive error targeted were based on expert consensus, population-based data on the prevalence or incidence of amblyopia with various levels of refractive error are scarce, and little is known about the optimal management of these refractive errors once they are identified, especially in children who may be too young for optotype visual acuity testing. Thus, further research is needed to determine the best approach to reducing the burden of amblyopia in the population. In the meantime, photoscreening remains one of the more promising modalities available.