Screening for amblyogenic factors using a volunteer lay network and the MTI PhotoScreener

Donahue et al 䡠 Photoscreening of Preliterate Children Discussion by Kurt Simons, PhD This report1 represents something of a landmark, detailing the largest photoscreening study yet reported. What makes this large size particularly noteworthy is that data quality standards were maintained despite those large numbers, a formidable undertaking. Six hundred ten volunteers were trained, not simply via lecture presentation, but with supervised screening, until less than 10% of their screening photographs were unreadable. The photographs were then interpreted by experienced ophthalmologic photograph readers at an academic reading center, with the still further precaution taken of the readers having their interpretations monitored by Dr. Donahue for the first 2000 photographs processed. When parents did not comply with a referral, they were contacted as many as three times, and eye care personnel who were known to have seen referrals from the study were contacted if they did not submit a report to the study. However, although they make the study’s level of achievement more impressive, two major problems it faced would appear to have wide implications. The first was that, of those 610 screeners who were trained, only 206 (34%) did any screening at all and only 134 (22%) did more than two screenings. In other words, approximately three quarters of the training effort was wasted, and only approximately one quarter of the volunteers recruited were actually of substantive use to the project. Furthermore, despite the fact that virtually all the children screened were covered by insurance, only 29% of the ophthalmologists in the state and 20.5% of the optometrists were willing to take referrals from the study. The end result of this effort, then, is that, despite the scale of its achievement, of a state population of 263,000 children in the study’s age range, only 15,059 of 263,000, or 5.7%, were able to be screened. In other words, despite the use of a technology that could be realistically applied to screening at these young ages, despite the great efforts of those who were involved, and despite the availability of a funded central administration and reading center, the project was only able to screen approximately one child in 20. This adds another demonstration, if one is needed, that providing anything approximating universal preschool vision screening in the United States will require a mechanism beyond what can be accomplished by a volunteer-based model. Whether provision of adequate funding alone would assure wider coverage or whether some form of mandate would also be required has yet to be determined. A second feature of note in this study is the failure criteria used, which are some of the most elaborate yet devised for the instrument used, based on a pupil-size calibration made by Dr. Donahue and his colleagues as yet another preparation for the study. What is noteworthy here is the wide variation in failure criteria and interpretation across studies of just this one instrument. Thus, for instance, the manufacturer’s own instruction manual has two different sets of criteria, one in the front of the manual (pp. 38 –39), another in the back (pp. 87–91),2 with the latter based on a set of pupil-size–related calibration curves, but different from those of Dr. Donahue and colleagues,1 and with the astigmatism and an-

From the Pediatric Vision Laboratory, Krieger Children’s Eye Center, The Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, Maryland. Address correspondence to Kurt Simons, PhD, Pediatric Vision Laboratory, Krieger Children’s Eye Center, The Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, MD 21287. E-mail: [email protected].

isometropia failure criteria not clearly specified.2 One study varied the hyperopia criteria with age3 and used a set of calibration curves different from either those of the manufacturer’s manual or Dr. Donahue and colleagues, whereas others have used simple crescent-size– based algorithms4,5 or not explicitly reported their criteria.6 Some studies have used global sensitivity and specificity measures,7–9 whereas others have reported sensitivy and specificity by specific type of deviation or refractive error.10 –13 The second conclusion to be drawn here, then, would appear to be that there remains a need for some form of standardization of failure criteria, as well as of test conditions (e.g., participant age, type and amount of refractive error being detected) to allow adequate and meaningful evaluation of the efficacy of both photoscreening generically and of specific photoscreening instruments.14 References 1. Donahue SP, Johnson TM, Leonard-Martin TC. Screening for amblyogenic factors using a volunteer lay network: initial results from a statewide program targeting preliterate children. Ophthalmology 2000;1637–1644. 2. The MTI Photoscreener Instruction and Interpretation Manual. Cedar Falls, IA: Medical Technology, Inc, 1994. 3. Freedman HL, Preston KL. Polaroid photoscreening for amblyogenic factors. An improved methodology. Ophthalmology 1992;99:1785–95. 4. Weinand F, Gra¨f M, Demming K. Sensitivity of the MTI photoscreener for amblyogenic factors in infancy and early childhood. Graefes Arch Clin Exp Ophthalmol 1998;236: 801–5. 5. Tong PY, Macke JP, Bassin RE, et al. Screening for amblyopia in preverbal children with photoscreening photographs. III. Improved grading for hyperopia. National Children’s Eye Care Foundation Vision Screening Study Group. Ophthalmology 2000;1630 –1636. 6. Lewis RC, Marsh-Tootle WL. The reliability of interpretation of photoscreening results with the MTI PS-100 in Headstart school children. J Am Optom Assoc 1995;66:429 –34. 7. Ottar WL, Scott WE, Holgado SI. Photoscreening for amblyogenic factors. J Pediatr Ophthalmol Strabismus 1995;32:289 – 95. 8. Hatch SW, Tibbles CD, Mestitio IR, et al. Validity and reliability of the MTI photoscreener. Optom Vis Sci 1997;74: 859 – 64. 9. Holgado SI, Arfeli S, Gomez-Demmel E, Espinosa J. Comparative study of the MTI photoscreener,™ visual acuity and Lang stereopsis test for amblyogenic factors in mentally delayed children. Am Orthoptic J 1998;48:122–30. 10. Tong PY, Enke-Miyazaki E, Bassin RE, et al. Screening for amblyopia in preverbal children with photoscreening photographs. National Children’s Eye Care Foundation Vision Screening Study Group. Ophthalmology 1998;105:856 – 63. 11. Schworm HD, Kau C, Reindl B, et al. Photoscreening zur Fru¨herkennung amblyopieauslo¨sender Augenvera¨nderungen. Klin Monatsbl Augenheilkd 1997;210:158 – 64. 12. Simons BD, Siatkowski RM, Schiffman JC, et al. Pediatric photoscreening for strabismus and refractive errors in a highrisk population. Ophthalmology 1999;106:1073– 80.

1645

Ophthalmology Volume 107, Number 9, September 2000 13. Tong PY, Macke JP, Bassin RE, et al. National Children’s Eye Care Foundation Vision Screening Study Group. Screening for amblyopia in preverbal children with photoscreening photographs. II. Sensitivity and specificity of the MTI photoscreener. Ophthalmology 2000;1623–1629.

14. Simons K. Vision screening techniques: a survey. In: Hartmann EE, ed. Vision Screening in the Preschool Child. Genetic Services Branch, Maternal and Child Health Bureau, Health Resources and Services Administration, US Department of Health and Human Services, 1999.

Historical Image This advertisement appeared in the New Braunfels Zeitung of January 24, 1901. It alerted readers of the newspaper to an impending visit to New Braunfels, Texas, by Dr. H. Robinson of Waco on January 30th and 31st. The advertisement was part of a four page supplement extolling Dr. Robinson’s skills in treating eye diseases and outlining the medications and devices he used to effect cures. It also contained testimonials from grateful patients, including one from R. B. Hubbard, a former governor of the State. Dr. Robinson will not be appearing at the annual meeting of the American Academy of Ophthalmology that will be held in Dallas in October, 2000.

(Historical image and caption provided courtesy of Andrew P. Ferry, MD, Richmond, Virginia.)

1646