Journal of Pediatric Ophthalmology and Strabismus

The Feasibility of Introducing a Visual Screening Test for Children During Vaccination Campaigns

Marisa B Potério, MD; José Augusto Cardillo, MD; Firmane De Senne, MD; Ricardo Pelegrino, MD; Newton Kara José, MD; Denise Y J Norato, MD; Glória MariaB Potério, MD

Abstract

Abstract

Purpose: A visual screening test for children was prepared for the use of paramedics during vaccination campaigns. This test was used in a vaccination campaign in Taquaritinga, Säo Paulo, Brazil.

Methods: The campaign was carried out by two paramedics trained by ophthalmologists. The first 130 children vaccinated whose families showed interest in participating in the visual screening program were chosen. The program consisted of demographic information and eight questions, a visual screening test for children >4 years, and an external eye examination. After studying the data collected, the paramedic decided if the child needed a more thorough ophthalmologic examination.

Results: Of the 4505 children vaccinated, 130 children participated in the screening test. One (76.9%) hundred of the 1 30 children were reexamined by ophthalmologists. Of these, 38 (29.2%) were initially considered to have visual disorders. Ophthalmologic disorders were confirmed in 22 (57.9 %) children; of these, 3 were already under ophthalmologic care. The paramedics correctly screened a total of 77 (77%) children.

Conclusion: Visual screening during vaccination campaigns is simple and rapid, and provides the opportunity to identify children with visual disorders during the critical stage of visual development without the need of ophthalmologists.

Journal of Pediatric Ophthalmology and Strabismus; 2000;37:68-72.

Abstract

Abstract

Purpose: A visual screening test for children was prepared for the use of paramedics during vaccination campaigns. This test was used in a vaccination campaign in Taquaritinga, Säo Paulo, Brazil.

Methods: The campaign was carried out by two paramedics trained by ophthalmologists. The first 130 children vaccinated whose families showed interest in participating in the visual screening program were chosen. The program consisted of demographic information and eight questions, a visual screening test for children >4 years, and an external eye examination. After studying the data collected, the paramedic decided if the child needed a more thorough ophthalmologic examination.

Results: Of the 4505 children vaccinated, 130 children participated in the screening test. One (76.9%) hundred of the 1 30 children were reexamined by ophthalmologists. Of these, 38 (29.2%) were initially considered to have visual disorders. Ophthalmologic disorders were confirmed in 22 (57.9 %) children; of these, 3 were already under ophthalmologic care. The paramedics correctly screened a total of 77 (77%) children.

Conclusion: Visual screening during vaccination campaigns is simple and rapid, and provides the opportunity to identify children with visual disorders during the critical stage of visual development without the need of ophthalmologists.

Journal of Pediatric Ophthalmology and Strabismus; 2000;37:68-72.

INTRODUCTION

Discovery and correction of ocular defects early in life is of the utmost importance for preventing persisrent amblyopia and achieveming optimal binocular function.1 To prevent or treat serious ocular problems, examination of children should begin before there are any symptoms of poor vision. However, children who do not show signs of poor vision after birth, did not have problems during the embryogenic period, and have normal development are rarely taken for an Ophthalmologie examination. Most children are examined only when they demonstrate visual problems that are detected by the family or by teachers in school. Therefore, these children often do not receive adequate treatment during the period of visual development. This indicates the necessity of introducing a visual screening test in the public health system.2

The World Health Organization (WHO) has developed programs with the participation of specialists and the community to increase awareness of the necessity of early ophthalmologic screening. The WHO reinforces the fact that "effective programs require systematic community action to eliminate blindness and visual disorders."2-4

The key to the success of preventive programs is the competence of members of die community and their influence on the population. These characteristics often are found in teachers, social assistants, religious leaders, and in specialized or unspecialized members of a health team.3 Parents must recognize the investigation as being of importance for their children's health.

Many preventive programs are already well organized such as vaccination, breast-feeding, cancer prevention, and acquired immunodeficiency syndrome prevention campaigns. The vaccination campaign has established itself as a program involving different social classes of the community and covering an age group still undergoing visual development. In view of this fact, the possibility of increasing the social impact of this program by introducing an ophthalmologic examination using the same paramedics was considered.

There is an abundance of literature concerning vision screening in preschool-aged children with varying results. In addition, the ophthalmologic findings of the referred children show great disparity. These divergences are due to biased samples and to differences in screening methods, referral criteria, and professional evaluation and follow-up.1

This study evaluated the effectiveness of a simplified, standardized ophthalmologic examination performed by paramedics in detecting visual disorders in children during a vaccination campaign in Taquaritinga, Säo Paulo, Brazil.

MATERIALS AND METHODS

A visual screening test for children ≤5 years old was performed during a vaccination campaign in Taquaritinga, Säo Paulo, Brazil, in August 1994. The screening was carried out by two paramedics who were trained by ophthalmologists at UNICAMP. The first 130 children vaccinated whose families showed an interest in participating in the visual screening program were chosen.

The form for the program consisted of demographic information and eight brief "yes/no" questions. The questions were answered by the adult accompanying the child and covered family perception of altered vision, ocular anatomic alterations, progress at school, and neuropsychomotor development of the child. The visual screening test used by the paramedics included a visual acuity (VA) test and an external eye examination, and took an average of 4 minutes to perform. The VA examination was given only to children >4 years who cooperated with distance evaluation using the Allen table. Each eye was tested separately, with optical correction if worn, at a distance of 5 m, and the smallest line correcdy read was recorded for each eye.

After studying the data collected, the paramedic decided if the child needed a more thorough ophthalmologic examination. The children screened during the vaccination campaign were divided into six groups according to their ages and recalled to be examined by two ophthalmologists at UNICAMP. The returning children were examined using the same VA test performed in the first screening, as well as Hirschberg, cover test, fly stereo test (Titmus), cycloplegic refraction by retinoscopy, biomicroscopy, and eye fundus using indirect ophthalmoscopy.

The results of those patients who completed the entire form and the second phase testing were analyzed, and the results obtained by the paramedics were compared to the results of the ophthalmologists. When studying VA, the difference in the fines noted by the examiners was compared. The criteria for positive referral to an ophthalmologist were VA <20/20 in either eye or 0.2 difference between the eyes. Stereo acuity by Titmus testing 2* 100 seconds of arc was considered normal.5'7 Hyperopia <+3 diopters (D) and astigmatism <0.75 D were not considered a significant alteration.

RESULTS

One hundred thirty of 4505 children who were vaccinated participated in the visual screening program. All 130 children were recalled for a complete ophthalmologic examination by ophthalmologists, of which 100 (76.9%) children returned. Thirty (23.1%) children did not return for the examination despite several reminders; these 30 children were excluded from the study.

Table

TABLE 1POSITIVE CASES CONSIDERED BY PARAMEDICS ACCORDING TO AGE AND RESULTS IN THE FIRST PHASE

TABLE 1

POSITIVE CASES CONSIDERED BY PARAMEDICS ACCORDING TO AGE AND RESULTS IN THE FIRST PHASE

Table

TABLE 2COMPARISON OF VISUAL SCREENING AND OPHTHALMOLOGIC EXAMINATION FOR CHILDREN CONSIDERED NORMAL BY THE PARAMEDICS AND ALTERED BY THE OPHTHALMOLOGISTS

TABLE 2

COMPARISON OF VISUAL SCREENING AND OPHTHALMOLOGIC EXAMINATION FOR CHILDREN CONSIDERED NORMAL BY THE PARAMEDICS AND ALTERED BY THE OPHTHALMOLOGISTS

Thirty-eight (29.2%) children considered to have some padiologic disorder returned for the second phase. Table 1 shows the distribution of the participating children according to the reason for suspected ocular disorder detected during visual screening by die paramedics. Padiologic alterations were confirmed in 22 (57.9%) children. Of the 62 children who participated in the second phase and were considered normal by the paramedics, the ophthalmologists detected padiologic alterations in 7 (11.3%) children (Table 2). The paramedics screened correcdy a total of 77 (77%) children.

A review of the answers related to the items clinical history and external examination showed strabismus as the most frequent alteration (14%), followed by VA alteration noticed by die family (13%), photophobia (9%), red eye (7%), eyelid alteration (5%), big eye (5%), watery eye (4%), and secretion (3%).

There was direct association of VA examinations conducted in the two phases of the project in 18 (47.4%) children. A one-line difference was found in 9 (23.7%) children and a two-line difference was found in 3 (7.9%) children. In 8 (21.1%) children, VA was carried out only in the second phase.

Table

TABLE 3TITMUS TEST RESULTS OBTAINED BY THE OPHTHALMOLOGISTS

TABLE 3

TITMUS TEST RESULTS OBTAINED BY THE OPHTHALMOLOGISTS

Table

TABLE 4OCULAR PATHOLOGIES DETECTED BY THE OPHTHALMOLOGISTS

TABLE 4

OCULAR PATHOLOGIES DETECTED BY THE OPHTHALMOLOGISTS

The 3 children with a two-line difference were examined for ocular padiology. However, only 1 of the 3 had ocular padiology. Similarly, of the 5 children with a one-line difference, only 3 children had ocular pathology. The VA test conducted in the first phase detected ocular alterations in 2 children, 4-5 years old, who had an unremarkable clinical history and external examination.

The results of the cover and Hirschberg tests confirmed strabismus in 9 (64.3%) of the 14 children who were referred by the visual screening with suspected strabismus and returned for the second phase of the program. The fly test was performed in 36 children (Table 3). No sex difference was found in any of the results (P>.05).

Ocular padiology detected at the end of the examinations by the ophthalmologists are shown on Table 4. Altogether, 29% of the children had a significant eye disorder and needed treatment or observation.

DISCUSSION

Visual disturbances in children fulfil the requirements that motivate directed screening procedures; they are common and may cause serious handicap later in life.8"10 Simple, reliable, and inexpensive screening methods and efficient treatment are available."12

In this study, 100 (76.9%) children returned for the second phase of testing. Of diese, 38% were suspected of having ocular pathology. Those who did not return remained without an ophthalmologic evaluation. This is disturbing because 9.2% of diese children showed indices of an ophthalmologic alteration during the visual screening.

A study of the results showed a high percentage of false positives (42.1%) but a low percentage of false negatives (11.3%). Visual screening as proposed had a 75.9% sensibility and 77.5% specificity, 57.9% positive predictive value, and 88.7% negative predictive value. Further evaluation of the protocol taking into account which items correcdy discriminated padiologic and normal cases probably could enhance specificity but could diminish sensibility by a low value of false positives. It could be possible with a special orientation using a small group of children to solve paramedic doubts before die campaign. The paramedics did die screening without a complete ophthalmologic examination to help determine die real pathologic cases, and they considered all children with alterations in even one item in the protocol as a possible pathologic cases. This fact made them select a larger number of children as having possible ocular alterations, thereby increasing sensitivity at the expense of specificity. Similar results were observed in a previous study in tests carried out in public school students.3

The first phase external examinations showed a high incidence of strabismus (14%), with confirmation of 9% in the second phase. This percentage is high when compared to research data that show a frequency of approximately 4% of strabismus in preschool- and school-aged children.13'14 The high percentage of strabismus observed in this study is probably related to selection bias in which the family perceived an ocular problem and enrolled the child in the study. All cases of strabismus were detected through clinical history and external examination; however, specific examinations for detecting strabismus, such as the Hirschberg and cover tests, should be included in the first phase and would contribute to a lower false-positive value.

The VA test is an important criteria for the paramedics in selecting cases suspected of having ocular pathology. The results of the test in the two phases were similar in 47.4% cases, and the difference of one line in 23.7% cases was considered insignificant. Only 3 cases of suspected ocular pathology by VA criteria were considered normal after the second phase of the examination. Of the 7 false-negative cases reported as normal by the paramedics, 5 showed significant alteration during VA test on the second phase and refractive errors confirmed by the cycloplegic refraction. The paramedics had difficulty in capturing the child's attention to answer the examiner's questions correctly, which has been observed in other studies.3'6'15 The fly test alone was not efficient in detecting significant eye disorders but may be used as a complement to the normal VA test. Similar results have been found by other authors.11,16'17

CONCLUSION

The paramedics succeeded in adequately screening most of the cases, detecting treatable ophthalmologic pathology that could permanently affect vision. The VA test was efficient in the initial phase although limited by difficulty in capturing the children's attention. There was a positive response from the population with reference to the ophthalmologic examination, shown by the large number of children who returned for the second phase. It can be concluded that ophthalmologic screening is important and can be effectively conducted by paramedics during campaigns that attract children in the critical age group to detect visual alterations that can be corrected. To diminish the frequency of false-positive results, improved training is recommended for the paramedics.

References

1. Köhler L, Stigmar G. Vision screening of 4-year-old children. Acta Patdiatr Scand. 1973;62:17-27.

2. Temperini ER, José NK, Rigolizzo HB. Envolvimento de pessoal da comunidade em projeco de detecçâo de ambliopia cm préescolares. Arq Bras OfiaL 1983;46:85-89.

3. Temporim ER, José NK, Taiar A, Ferrarini ML. Validade da afericáo da acuidade visual realizada pelo professor em escolares de primeira a quarta série de primeiro grau de urna escola pública do municipio de Sao Paulo, Brasil. Rev Saude Pública. 1997:229-37.

4. World Health Organization. Guidelines for Programs for the Prevention of Blindness. Geneva, Switzerland: World Health Organization; 1979.

5. Cunha LAP. Acuidade Visual e Visáo Estereoscópica em Crianças. Seu Papel na Indicaçâo de Exame Oftalmológico. Tese de DouUrado resentada à Faculdade de Medicina da Universidade de Säo Paulo Sea de Oftalmologia, 1988.

6. José NK, Temporim ER. Avaliaçâo dos criterios de triagem visual de escolares de primeira série do primeiro grau. Rev Saude Pública. 1980:14:205-214.

7. Pereira VX, José NK, Costa MN, et al. Estudo de estereopsia em pré-escolares da cidade de Paulfnia, Sao Paulo. Arq Bras OfiaL· 1979;42:268-274.

8. Kripke SS, Dunbar CA, Zimmerman V. Vision screening of preschool children in mobile clinics in Iowa. Public Health Rep. 1970;85:41-44.

9. Lippmann O. Vision screening of young children. Am J Public Health. 1971;61:1586-1601.

10. Shevlin FB. The school ophthalmic service. Public Health. 1961;64:143.

11. Lippmann O. Eye screening. Arch Ophthalmol. 1962:68: 148.

12. The incidence and results of treatment of reduced vision acuity due to refractive errors in 4 year old children in a Swedish population. Acta Ophthalmol Scand. 1966:44:152.

13. Costa MN, José NK, Machiaverni Filho N, et al. Estudo da incidencia de ambliopia, estrabismo e anisometropia em pré-escolares. Arq Bros OfiaL 1979; 42:249-251.

14. Weinstock VM. Weinstock DJ, Kraft SP. Screening for childhood strabismus by primary care physicians. Can Fam Physician. 1998; 44:337-343.

15. Johnson AM. Visual problems in children: detection and referral. journal of the Royal College of General Practitioners. 1984;34:32-35.

16. Oliver M, Nawratzki 1. Screening of preschool children for ocular anomalies, I: screening methods and their ptacticabiliry at different ages. BrJOphthalmoL 1971:55:462-466.

17. Taubenhaus LJ, Jackson AA. Vision Screening of 3 Through 5 Year Old Children: Final Report. Brookline, Mass: Health Department; 1967.

TABLE 1

POSITIVE CASES CONSIDERED BY PARAMEDICS ACCORDING TO AGE AND RESULTS IN THE FIRST PHASE

TABLE 2

COMPARISON OF VISUAL SCREENING AND OPHTHALMOLOGIC EXAMINATION FOR CHILDREN CONSIDERED NORMAL BY THE PARAMEDICS AND ALTERED BY THE OPHTHALMOLOGISTS

TABLE 3

TITMUS TEST RESULTS OBTAINED BY THE OPHTHALMOLOGISTS

TABLE 4

OCULAR PATHOLOGIES DETECTED BY THE OPHTHALMOLOGISTS

10.3928/0191-3913-20000301-04

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