The role of vision screening and classroom illumination in the vision health of Korean school children.
Vision screening generally proves effective for preschool and school-aged children, whereas providing self-tests and teaching the value of vision health prove effective for middle school students. (6,8) Vision screening is part of an annual physical examination conducted by primary schools that submit results to the Ministry of Education and Human Resources (School Physical Examination Act Articles, 3 and 11). Screening procedures, location of screening, lighting, and distance from the Snellen chart vary from school to school, and most schools do not comply with the standard. Therefore, many professionals express concerns about the validity of the tests (3,4,8,10,11) and about the under-referral and poor follow-up care of the subnormal visual acuity (SVA) group after the test. (5,6,12,13)
Illumination levels in many kindergartens and primary schools do not meet recommended levels. Specific recommendations from the Korea Standard Association (KSA) for school illumination can serve as reference points to examine illumination levels in schools. The KSA recommend 300Lux to 600Lux for reading and writing, and 1,500Lux as the maximum allowable level for performing precise work under low brightness. (14) For precise work, KSA recommends 2,000Lux for focal lighting, with regular room lighting to minimize harmful effects from high-intensity focal lighting.
This project examined vision health of children from grades K-12; compared results of the Snellen test with the automatic vision test; and analyzed the illumination status of learning environments, including classrooms, computer rooms, and laboratories, in primary schools and kindergartens.
With approval of parents and school principals (the standard procedure for human subject recruitment in Korea), all students in grades one and two in one urban school in Honam province (southwest region of Korea), and all students in kindergartens and in one class from grades one to six in four rural schools in the same province, were asked to participate in the project. All agreed to participate.
Three instruments were used. For vision screening, the Snellen chart and automatic SS-3 instrument (Topcon, Japan) were used. The Snellen chart was regarded as a universally accepted method, and the automatic SS-3 was considered a valid, reliable, accurate, and sensitive instrument because its use was authorized by the provincial Health Center. The SS-3 was easy to use but more expensive than the Snellen chart. Status of school illumination was examined using the digital illumination meter (TES-1330) authorized by the Bureau of District School Health in Korea.
The Snellen chart was used following standard guidelines. For the automatic vision test, an optometrist from Chonnam National University Hospital trained five school nurses, who then conducted the test following a specified procedure. Visual acuity equal to or less than 0.7 in one eye or both eyes was counted as subnormal visual acuity, according to the guidelines for school physical examinations in Korea.
Five school nurses examined illumination status of primary schools and kindergartens using the TES-1330 digital illumination meter between 10 - 11 am on sunny days and on cloudy days. Illumination was measured in classrooms, computer rooms, and laboratories children use frequently. Following a standard protocol, illumination was checked at nine points on the surface of desks in the rooms and at three points in front of the chalkboard (Figure 1).
[FIGURE 1 OMITTED]
Vision screening and illumination were examined twice, during October and November 1999, and during May and June 2000. School illumination was computed by averaging measures of each point from five schools. Descriptive statistics and [chi square] test using SPSS-PC program were used for data analysis.
Participants included 92 students in kindergarten (13.9%); 191 in grade one (28.9%); 181 in grade two (27.5%); 45 in grade three (6.8%); 46 in grade four (7.0); 56 in grade five (8.5%); and 49 in grade six (7.4%). Boys constituted 52.0% of the total population, and children living in urban areas constituted 84.2%.
Visual Acuity by Screening Method
The Snellen test detected subnormal visual acuity in 14 kindergarten students (15.2%) on the right eye, and 12 (13.0%) on the left eye; and in 31 (30.4%) fiftth graders and sixth graders on the right eye, and 26 (25.5%) on the left eye. Visual acuity differed significantly among grades for the right eye ([chi square] = 18.55, p = .001), and for the left eye ([chi square] = 12.88, p = .005). Distribution of visual acuity using the SS-3 instrument was similar to the Snellen test, but the automatic test showed more children with subnormal visual acuity (Table 1).
Visual Acuity by Gender, Grade, and Area
The Snellen test showed significant differences in subnormal visual acuity which was seen in more girls than boys ([chi square] = 9.07, p = .003); more upper graders than lower graders ([chi square] = 9.62, p = .022); and more children living in urban areas than those in rural areas ([chi square] = 8.75, p = .003). The automatic test showed similar results (Table 2).
On sunny days, classroom illumination was 3,040Lux in front of the window point, 920Lux at the rear middle, and 328Lux at the rear aisle points. The same points in kindergarten were relatively low: 1,587Lux, 850Lux, and 360Lux. Wide differences occurred in the points measured, ranging from 3,040Lux to 328Lux in the same classroom in primary schools; 1,587Lux to 360Lux in the kindergarten. On cloudy days, illumination of the middle and aisle parts were almost under the minimum recommended standard of 300Lux (Table 3).
Illumination around the chalkboard was relatively lower than the classroom. On sunny days, average illumination in front of the chalkboard was from 1,533Lux at window side and 588Lux at aisle side. On cloudy days, classroom illumination levels from the middle to the aisle side of the chalkboard were less than 300Lux (Table 4).
Until the School Physical Examination Act was revised in 1999, Korea did not routinely conduct vision screening for kindergarten children. Results from this project showed subnormal visual acuity as high as 15% among kindergarten children, and it increased with increasing grades. The fifth and sixth graders showed 28.4%. Similar results were shown by others in Korea.29 Ahn and Kweon (15) reported subnormal visual acuity of 17.3% for primary school children in a large city in the early 1980s; Yoo et al. (16) reported subnormal visual acuity of 1 1.4% among six-year-old children; and Koo and colleagues (17) reported subnormal visual acuity of 38.8% among urban primary, junior, and high school students in the late 1980s. Similarities of previous results with the findings from this project suggest visual acuity of children should be assessed from an early age (at least from kindergarten) and followed up annually.
In this project, gender and location of schools made significant differences in subnormal visual acuity of children. Girls and children living in urban areas showed more subnormal visual acuity than boys and those living in rural areas. Similar results were reported by researchers who showed girls and children in urban areas had markedly more subnormal visual acuity. (2,9,16,18-20)
Several factors may contribute to increased subnormal visual acuity among Korean children. Contemporary lifestyles may play a major role. Increased use of computers, playing with hand-held computer games, and watching television too close to the screen (1,9,17) might be factors. Excessive use of display screens, (17,21) reading too much or working too closely to the eyes, (19) eye diseases, (22) sitting posture, (20) and low illumination (17) also were reported as influencing the vision health of children. Diet and poor nutrition (20) also may play a role.
Though preschool vision screening is not mandatory, some data exist on preschool vision screening and methods in Korea. (3,23) These studies advocated early vision screening for detecting abnormal vision problems and follow-up care. Vision screening for preschool children has been accepted as routine in the United States for decades. (5,25) Such early vision screening data have created baseline information for follow-up of reflective error and visual problems during primary schooling. However, some question the validity of vision screening for three-to four-year-old children, (5,11,24) largely from concerns about children's readiness to follow the screening procedure.
In western countries, studies focused on identifying more valid screening tests for preschool children (10,26,27,29,30) and primary school children. (28) These tests include a computer-based screening test for school-aged children, (28) the perception test, (23) and the MTI photo-screener (27) for preschool children. A review of the MEDLINE database on vision screening tests for detection of amblyopia from 1966 to January 1999 indicated considerable inter-observer variability in the interpretation of photo-screening results. (26) To decrease inter-rater variability, standard criteria for interpreting results from vision screening tests need to be developed.
This project found the current Snellen chart still useful and reliable if guidelines and procedures were followed accurately. However, the guidelines are difficult to follow completely in Korea because only one school nurse is assigned to a school regardless of size. For instance, one school nurse may attend to thousands of students in an urban primary school, making it almost impossible to do the job satisfactorily. Yet, when an automatic instrument was tested, school nurses found it easy to use, and they could follow up children's vision care more easily and effectively. It also increased interest in vision health among teachers. At least one automatic vision screening instrument should be placed at each school in urban areas and at the village level in rural areas.
Several issues emerged in western countries concerning follow-up care from school vision screening. Examples include over-referral or under-referral after school vision screening; (5,12) noncompliance on follow-up care; (13) lack of support from community health professionals and school authorities; (6) and concern about the value of follow-up care from eye specialists. (5,6,31) These issues do not refute the importance of mandatory vision screening from the kindergarten age in Korea.
Illumination of school classes and other learning environments play an important role in students' learning. Yet, only limited data address the status of school illumination in Korea. Most window sites in classrooms exceeded 1,500Lux (the maximum allowable level), and reached 3,040Lux on sunny days. On cloudy days, all middle and aisle sites of classrooms were darker than 300Lux, clearly below the minimum standard and not conducive for optimal learning. Schools should create an environment for preventing glaring sunlight on sunny days and maintaining minimum illumination for cloudy days. The results of this study differed from the findings of a Romanian study that showed the difference in school illumination between urban and rural areas. (32)
Illumination also affected results of various vision tests. (33,34) Under low illumination conditions, the pupil enlarges, which eventually affects vision health, often leading children to wear glasses. (35) People with subnormal visual acuity can achieve the best visual acuity with an illumination level of 500-1,000Lux. (34)
Vision health of kindergarten and primary school children can improve with regular vision screening from kindergarten and with optimal illumination levels in the learning environments of schools. The increasing rate of subnormal visual acuity from kindergarten to higher grades in primary schools suggests the necessity of enforcing annual check-ups from kindergarteners. An easy-to-use but equally effective screening instrument such as the SS-3 automatic instrument can enhance more accurate screening, albeit more expensive. Illumination of classrooms and other learning environments must maintain standard levels of illumination regardless of weather conditions with proper window blinds to prevent glaring sunlight. Conversely, middle and aisle sites need brighter lights to prevent excessive and constant dilation of the pupil commonly seen in low illumination conditions.
Table 1 Visual Acuity by Snellen and Automatic Tests NVAG SVAG Snellen Automatic Snellen N (%) N (%) N (%) Right Eye Preschooler 78 (84.8) 75 (81.5) 14 (15.2) 1st - 2nd 313 (86.5) 291 (81.1) 49 (13.5) 3rd - 4th 68 (75.6) 60 (66.7) 22 (24.4) 5th - 6th 71 (69.6) 67 (65.7) 31 (30.4) Left Eye Preschooler 80 (87.0) 78 (84.8) 12 (13.0) 1st - 2nd 316 (87.3) 308 (85.8) 46 (12.7) 3rd - 4th 70 (77.8) 66 (73.3) 20 (22.2) 5th - 6th 76 (74.5) 75 (73.5) 26 (25.5) [x.sup.2] p Automatic N (%) Snellen Automatic Right Eye Preschooler 17 (18.5) 18.55 .001 1st - 2nd 68 (18.9) 16.99 .001 3rd - 4th 30 (33.3) 5th - 6th 35 (34.3) Left Eye Preschooler 14 (15.2) 12.88 .005 1st - 2nd 51 (14.2) 13.50 .004 3rd - 4th 24 (26.7) 5th - 6th 27 (26.5) NVAG (Normal Visual Acuity Group): visual acuity > 0.7 SVAG (Subnormal Visual Acuity Group): visual acuity [less than or equal to] 0.7 Table 2 Visual Acuity by Gender, Grade of Children, and School Area in Snellen and Automatic Tests Snellen NVAG SVAG N (%) N (%) [x.sup.2] p Gender Boy 250 (84.7) 46 (15.5) 9.07 .003 Girl 202 (74.3) 70 (25.7) Grade 1st - 2nd 303 (83.2) 61 (16.8) 9.62 .022 3rd - 4th 65 (73.0) 24 (27.0) 5th - 6th 73 (71.6) 29 (28.4) School Area Urban 370 (77.4) 108 (22.6) 8.75 .003 Rural 82 (91.1) 8 (8.9) Automatic NVAG SVAG N (%) N (%) [x.sup.2] p Gender Boy 249 (84.4) 46 (15.6) 15.83 .001 Girl 191 (70.5) 80 (29.5) Grade 1st - 2nd 280 (80.3) 81 (19.8) 7.65 .051 3rd - 4th 62 (69.7) 27 (30.3) 5th - 6th 75 (73.5) 27 (26.5) School Area Urban 359 (75.4) 117 (24.6) 9.30 .002 Rural 81 (90.0) 9 (10.0) NVAG (Normal Visual Acuity Group): visual acuity > 0.7 SVAG (Subnormal Visual Acuity Group): visual acuity [less than or equal to] 0.7 Table 3 Average Illumination of School on Sunny and Cloudy Days (Lux) Window Middle (1) (2) (3) (4) (5) Classroom S 3,040 2,488 2,645 820 920 C 403 405 368 247 267 Computer Room S 3,285 3,418 3,185 878 1,083 C 345 330 328 298 280 Lab. Room S 2,338 2,208 2,443 1,135 1,305 C 420 398 393 345 325 Kindergarten S 1,587 1,600 1,980 907 1,047 C 393 380 373 277 307 Aisle (6) (7) (8) (9) Classroom S 920 420 425 328 C 260 215 218 172 Computer Room S 1,035 470 518 363 C 280 215 228 218 Lab. Room S 1,388 538 603 483 C 340 255 221 222 Kindergarten S 850 570 547 360 C 273 210 193 141 S - Sunny Day; C - Cloudy Day Table 4 Average Illumination of Blackboard on Sunny and Cloudy Days (Lux) Sunny Day Cloudy Day (1) (2) (3) (1) (2) (3) Classroom 1,533 878 588 310 240 228 Computer Room 1,110 775 558 325 255 165 Lab. Room 1,053 933 568 323 263 173 Kindergarten 1,097 653 370 250 187 150 Figure 1 Measuring Points of School Illumination A. Chalkboard Measuring Points Top wi ai nd (1) (2) (3) sl ow e Bottom B. Classroom Measuring Points Front w (1) (4) (7) a i i n (2) (5) (8) s d l o (3) (6) (9) e w Rear
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Hae Young Kang, PhD, RN, Professor, Dept. of Nursing, College of Medicine, Chonnam National University, Chonnam Research Institute of Nursing Science, 5 Hakdong, Gwangju, Korea 501-746: (email@example.com); In Hyae Park, PhD, RN, Professor. Dept. of Nursing, College of Medicine, Chonnam National University, Chonnam Research Institute of Nursing Science, 5 Hakdong, Gwangju, Korea 501-746; (firstname.lastname@example.org); and Mi Ja Kim, PhD, RN, FAAN, Professor and Dean Emeritus, College of Nursing, University of Illinois at Chicago. Chicago, IL 60612; (email@example.com). This study was funded by the Ministry of Health and Social Welfare of Republic of Korea, Health Promotion Grant, 1999. This article was submitted April 2, 2003, and accepted for publication June 16, 2003.
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|Title Annotation:||Health Service Applications|
|Author:||Kang, Hae Young; Park, In Hyae; Kim, Mi Ja|
|Publication:||Journal of School Health|
|Date:||Nov 1, 2003|
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