Vision Screening Guidelines

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Background

South Africa needs specific guidelines in vision screening of certain focus groups that are at risk of developmental handicap, causing road accidents or is restricted in their potential to partake in the economy. Preventing blindness forms part of the responsibility of local health workers, industry and the community at large. The State and Local Authority more than often rely on input from the public to put the necessary infra structure in place but to sustain certain services, a public/private partnership is often the best structure to pursue.

A LAW FOR VISION SCREENING

Vision screening in South Africa is not prescribed by law accept under certain drivers licence regulations. School screening in Public Schools happens in an uncoordinated and fragmented way. The shared responsibility between the State, the Local Authority and the broader community results in a "buy in" situation that creates a continuous system that addresses a public need. This document identifies the focus groups that need specific attention. These groups are:

1. Those entering primary school.
Ideally children should be screened by the age of three but current logistical problems will not allow this to be a successful exercise. It was decided that the most effective screening point would be during grade one. However, certain preparatory schools may well decide to implement this prior to grade I.

2. Those entering high school.
The age group 11 to 15 years has been identified as a high-risk group and therefore will need routine vision screening.

3. All Public Transport workers.
This group will consist of all those who require a code EC drivers licence.

4. Those over the age of forty-five with the potential to be economically active.

In schools, local educators, vision screening personnel and eye care professionals should co-operatively determine which and when specific tests will be done and how the screening will be organised, thus ensuring a cost effective and efficient program. This document will seek to provide a maximum standard that may be implemented in part depending on the availability of resources within a particular situation.

SCHOOL SCREENING EXPERIENCES IN THE STATE OF INDIANA

According to a 1980 survey conducted by the (then) Division of Reading Effectiveness, the Indiana Department of Public Instruction and the I.U. School of Optometry, the most commonly used method of vision testing in Indiana public schools was the "Titmus Vision Tester" (74% of school corporations). Used properly, these vision tester units will detect more vision problems than just a Snellen chart at 20 feet. However, in actual use, these machines tend to fail children who do not have vision problems and fail only half the children who do have vision problems Further, the study found that nearly one half the schools were using their machine testers as portable space saving Snellen charts and, when used in this manner, they will do a poorer job than just a Snellen chart. The Snellen chart at 20 feet is the state's required minimum testing method and, until 1987, it was the second most commonly used. It fails fewer unnecessarily, but will miss more than half of those children needing vision care.

In 1980, the Modified Clinical Technique (MCT) was found to be already in use by 6.6% of Indiana public school corporations.16 since 1986, the MCT use rate has risen to over 90%. The MCT is actually composed of four different tests: (1) a distance Snellen chart for visual acuity, (2) a cover test to estimate ocular muscle balance, (3) an objective retinoscopy to estimate refractive error and (4) an ocular health inspection. It was designed and validated by a rigorous interdisciplinary study in 1959 (The Orinda Study). The MCT detects nearly all vision problems of children. With its high level of accuracy (95%), it is clear why the Indiana General Assembly chose to make the MCT the standard for vision screening in the public schools.

Presently, approximately 93% of all Indiana public school systems use the MCT, as directed by law.16 the chart below dramatically illustrate the rapid increase in the number of Indiana school corporations using the MCT.

GROUPS 1 & 2

GUIDELINES FOR SCHOOL SCREENING

1. All schools should conduct an annual vision test by:
a) The MCT method on either the preschool or first grade children. The choice of which grade is left up to the local School committee, but the proposal in this document is that children be tested at the earliest practical time.
b) Snellen Chart or equivalent visual acuity test on grades 3, 8, and all others suspected of having a visual defect.

2. The components of the MCT need to be defined. Records and reports are to be maintained and filed by Oct 1st of each school year.

3. If the MCT cannot be conducted, the school committee should still conduct a screening of visual acuity for grades 1,3 and 8.

ORGANIZING THE SCREENING PROGRAM
Introduction

The complexity of a comprehensive school vision screening program will vary considerably according to community size, the number of children screened and the number of 'eye care professionals available. Only a general organisational format can be outlined here. Educators, school nurses, eye care professionals and others who are aware of the guidelines must initiate the local program. Those interested and responsible should organize a meeting to discuss the various requirements of the vision screening and how the local school committee can most efficiently implement this mandated program. This meeting would allow those involved reviewing and discussing the various expected positive outcomes as well as possible problems of implementation and arriving at solutions agreeable to all. Representatives of public health, medicine, special education, parents and service organizations will be interested in learning about roles they may play in the vision-screening program. For most school committees, a close working relationship between local eye care professionals and school nurses will ensure that the program operates effectively and efficiently. It is suggested that the school nurse function as chief coordinator for all activities of those involved. Once the vision screening is completed and adequate time has passed for those who were referred to receive vision care, a follow-up meeting should occur to evaluate the program and receive recommendations for improvements from those involved.

ROLE OF THE LOCAL SCHOOL COMMITTEE

1) The school administrator shall be responsible for assigning the best-qualified person(s) in the school system or school health service for conducting, supervising, and assisting in eye screening.

2) The school administration shall be responsible for obtaining the services of a licensed eye health care professional.

The school nurse's role:
A Coordinate health programs
B Supervise personnel
C Evaluate health programs
D Contact families after referral
E Complete and return the Vision Screening Report.

Thus, it is recommended that the school administrator appoint the school nurse (or designee) as chairperson of the local vision screening committee. In that role, the nurse should identify the participants and convene the local committee to set the screening process in motion. The committee should consist of those with knowledge or ability to conduct and assist with the different components of the MCT.

With the potential personnel needs identified, the local coordinating Committee can determine the number of children needing to be screened each day and the local format for half- or full-day screenings. That information will help to determine the screening team composition and time format that is the most efficient and feasible for the given local circumstances. The following chart, Reflective of current optometric practice in South Africa should aid the local leaders in implementing their screening program.

The next important issue for consideration by the local planning committee is the screening format. Most schools will hopefully utilize the Modified Clinical Technique in one of three formats noted below. Depending upon local conditions, the following describes those formats that have been used successfully for efficient, cost effective screenings:

(1) The eye care professional, the school nurse and the screening team travel together to each individual school and perform the entire battery of tests in one session. This format is most suitable for small schools. The school nurse would need to return in two weeks to recheck any borderline findings and report them back to the eye care professional.

(2) For larger schools, the school nurse or screening personnel would conduct the visual acuity and, if directed by the eye care professionals also conduct one of the alternate binocular tests at the individual school(s) and record the data for each student. Later on a selected day, the eye care professional visits the individual school(s) and performs the ocular health and refractive error tests as time permits, with the school nurse conducting any visual acuity rechecks necessary.

(3) For several very small schools with limited eye care professionals, the school nurse or screening personnel would conduct the visual acuity and, if directed by the eye care professionals, also would conduct one of the alternate binocular tests at the individual schools and record the data for each student. One day is set aside and several schools and/or neighboring schools transport the students to a central location where the eye care professionals conduct the ocular health exam, refractive test and any retesting of binocular vision that may be needed. This format permits one or two professionals and the screening team to screen up to 200+ children per day.

As final plans are being made for the screening, attention must be given to the specific lighting and equipment requirements of each test being planned. The following chart provides valuable reminders for consideration of these requirements.

Note: The testing order presented here is only a suggestion, but it is good clinical practice to:
1) take history before any test,
2) conduct visual acuities first and cover test second before any lights are used on the eyes and while the child's responses are "fresh" and
3) Perform internal health exam last because of after-images and increased light sensitivity of children.

As the local leaders are considering a location for the screening, the issue of floor plans comes into play. Space and layout considerations must include
1) lighting,
2) ease of movement (in and out) and
3) space for holding children between screening stations, which allows for appropriate administration of each test component without undue noise and confusion.

RECOMMENDED SCREENING GUIDELINES & PROCEDURES

The Modified Clinical Technique was designed to be a flexible system in which several different tests could be used in each of the five component areas since the needs and resources vary from community to community. The following tests and auxiliary procedures are recommended in order to fulfill the clinical criteria for examination of children when using the Modified Clinical Technique.

IF A CHILD CURRENTLY WEARS GLASSES, ALL TESTING SHOULD BE DONE WITH THE GLASSES ON.

MCT Component #1

1. Although not required by law, a short visual health history from parents, teachers, etc. should be taken by the school nurse or aide prior to the screening. This should include observations and/or complaints about the child’s eyes, previous eye care, if glasses are worn and any observable behavior of eye strain (Teacher Observation Checklist, Addendum E, p. 41 and Sample Form, Addendum F, p. 42).

MCT Component #2

2. Visual acuities are standardized in Rule 1.1. by the use of the 6 meter

Snellen Chart, or a Tumbling E Chart. It is noted, however, that better results are obtained for pre-schoolers and first graders with a chart calibrated for a 3 meter distance and this can be used with the eye care practitioner’s recommendation.12 While a visual acuity of 6/12 for each eye is listed as passing on this component, most eye care practitioners recommend 6/9 as a more sensitive cut-off point for first graders. The best chart for testing kindergarten is the illiterate or Tumbling ”E” chart.20 This chart can be used, provided the child understands the “E game” and indicate the direction of the ”E” on the chart while covering one eye at a time. Even though children may know the alphabet, responses or cooperation on Snellen letter chart may be questionable. For those who fail, a simpler test must also be performed to verify acuity if below passing. This is necessary because a tester would not know whether the poor responses were due to poor vision or inability to recall the letters.

Alternatively, the Light House Picture Test© can be used on children who do not understand the ’E’ game.12, 20 Still another option is the use of machine vision screeners, but caution must be taken; young children often perform more poorly on these machines than they do on a standard Snellen chart.6 Before a child is referred for a visual acuity failure, the child must either fail a second part of the MCT or have the visual acuity retested within two weeks and fail again (Indications For Referral, p. 25).

MCT Component #3

3. There are two sub-components to the binocularity section of the MCT. These are muscle balance and stereopsis. The following are the currently used methods.

A. For testing muscle balance, the IBH/IBE and the Orinda study both recommend the Objective Cover Test, which must be conducted by an eye care professional. A child watches a distant fixation target (toy or picture) while the cover-uncover and alternate cover tests are performed. This is repeated at close proximity (13 inches) with a small fixation object or target. The amount of muscle imbalance can be estimated or neutralized by a prism bar. (Indications For Referral and Referral Criteria, p. 25).

B. The 2nd test for binocularity is stereopsis. Of the many stereopsis tests available, the Random Dot E Stereo –Test© (RDE) is recommended by the committee. The RDE© may well be the test most reflective of visual functioning.8, 18 The RDE© consists of two 8x10cm-test cards containing a Polaroid random dot pattern, a pair of Polaroid analyzer glasses and a demonstrator card. One of the test cards, when viewed through the Polaroid glasses under normal binocular conditions contains an ’E’; the other card does not. The test is conducted under normal classroom lighting with the child wearing the Polaroid glasses and his/her glasses, if worn. The child is first shown both cards at 50cm (20 inches), and instructed to point to the card with the ’E’. If the child can correctly identify the ’E’ card at 50 cm, the cards are moved out to 1 1/2 to 2 meters (5-7 feet), and presented again. The cards should be randomly shuffled and presented six times. Five correct answers out of six, or four successive correct answers are required to pass the test. As with all subjective tests, a retest is recommended before any referral or after any failure (Indications For Referral, p. 25). For further information on this test consult Jerome Rosner’s Pediatric Optometry, Butterworth Publishing, 2nd Edition, 1990.19

Other stereopsis tests are available such as the Frisby Stereo Test©, the Stereo Butterfly©, the Stereo Fly©, the Reindeer©, the Randot© and the TNO©. Findings of any of these tests are acceptable by the IBH/IBE. Of these, the committee recommends either the Stereo Butterfly© or the Randot©.

Alternately, if the above tests are not available and under the direction of an eye care professional, the binocularity tests may be conducted on a machine vision screener as long as the prior precautions are taken. Any failure on a machine vision screener needs to be verified in a retest two weeks later (Indications For Referral, p. 25). The tests recommended by the Committee are a distance-fusion test (the Keystone 3- ball test, or Worth 4-dot), the near fusion and the near muscle balance test. The distance muscle balance test is not recommended because of the high percentage of errors made by young children on the machine screeners, as noted by the Orinda Study.6

MCT Component #4

The recommended test for the objective refractive error of the eyes is retinoscopy (skiametry). This must be performed by an eye care professional. As a child watches a movie or slide cartoon at 3+ meters, a pair of +1.50 fogging glasses (readers) are placed over his/her eyes to relax focusing.17 The refractive error can be then estimated by focusing the light of the retinoscope by use of trial lenses, or a lens bar (Indications For Referral and Referral Criteria, p. 25).
For an additional measurement at ”66 cm for near vision” is not recommended, as retinoscopy performed with a near focus is not a test of refractive error, but is, in fact, a measure of accommodation.7

Two other methods for testing refractive errors have been used, autorefractors and the plus lens test as in the Wheel of Vision. Autorefractors are expensive pieces of equipment, but can be operated by a trained layperson and will provide a printed readout of the estimated power of the eye that can be analyzed later by the eye care professional. Often, a local eye care office might have one that can be loaned out.

MCT Component #5

The eye care professional should note the external and internal eye health of each child. A penlight and ophthalmoscope will be needed for this procedure.

Any referral or suggested follow up will needs to be executed by the school nurse in charge. A referral form must be filled in and depending on the urgency of the referral, followed within the time frame suggested by the eye care professional.

P. INDICATIONS FOR REFERRAL

1. The primary reason for a referral under an MCT vision screening would be either failure on any two sub-tests, or failure on an objective component, i.e., objective refraction, objective cover test (muscle balance) or ocular health.6 It is important that the test-retest method be used whenever a failure occurs on any subjective component, i.e., visual acuity, muscle balance on a Titmus Screener® or Random Dot E©. This is done by retesting a child on the failed subjective component two weeks after the initial screening; a second failure on the particular subjective test is an indication for a referral.

Q. VISION SCREENING CRITERIA: RECOMMENDATION FOR

REFERRAL

I. VISUAL ACUITY

Preschool and Grade 1:
Unable to read 6/12 with either eye
Difference of 2 or more lines
Unable to read 6/9 @ 40 cm
Grade 3: Unable to read 6/9 with each eye
Grade 8: Unable to read 6/6 with each eye

II. REFRACTIVE ERROR:

Preschool and/or Grade 1:
Refraction of +2.00 D or greater (hyperopia)
Refraction of -1.00 D or greater (myopia)
Astigmatism of 1.00 D or greater
Anisometropia of 1.00 D or greater

III. BINOCULAR COORDINATION

Preschool and/or Grade 1:
Manifest deviation of any size
Latent deviation of 10 esodeviation
Latent deviation of 8 exodeviation
Lack of stereo acuity

IV. ANY OCULAR ABNORMALITY

The above referral criteria were set loosely in order to accommodate the youngest and/or marginally cooperative preschoolers.

R. NOTIFICATION OF REFERRAL

The Committee recommends that the school nurse do notification for further care. Notification should be on school letterhead. The referral should specify no single eye care practitioner although practitioners conducting the testing would have been identified prior to the screening in the general notification to the public and parents. It is often helpful to the practitioner seeing the referral to know beforehand which component of the IBH/IBE criteria for the MCT the child did not meet. A sample letter of notification is offered in Addendum G, p. 43.

Minimum equipment

(1) The minimum equipment to be used shall be a Snellen Chart Illuminated by two (2) sixty- (60) watt bulbs.

(2) The Snellen E Chart shall be used for grade three (3).

(3) The Snellen Alphabetical Chart shall be used for grade eight (8). (4) The use of testing equipment equivalent to or more elaborate than the Snellen test is at the discretion of the local school system and shall be based on the recommendations of the school’s professional health advisory sources.

Testing procedures; standards

Procedures for vision testing are as follows:

(1) Equipment shall be used as follows: (A) The Snellen Chart (E or Alphabetical) shall be used at a distance of 6 meters.

(B) The lamps used to illuminate the chart shall be placed 30cm from the chart.

(2) The following standards apply: (A) Children in grade three (3) who are unable to read with each eye the 6/9 line of the Snellen Chart shall be recommended for further examination based upon the recommendations of the professional advisors of a school’s eye screening program. (B) Children in grade eight (8) who are unable to read with each eye the6/6 line of the Snellen Chart shall be recommended for further examination. (C) Parents of children with corrective lenses or other ocular devices shall be informed of the eye-screening program but these children need not be referred for further examination.

Qualification of testers Authority:

The school administrator shall assign the best-qualified person in the school system or school health service to supervise eye-screening tests

Reports

Reporting of School Testing Program (1) Each school committee shall submit an annual report of its vision-testing program to the Local Authority.

(2) The report shall include the following:
(A) the number of children in each grade tested;
(B) the number of children in each grade requiring further examination;
(C) the number of children receiving further professional attention;
(D) the type of screening test used;
(E) the person or department supervising the testing program. (3) The school’s testing program shall be subject to review and approval by the local educational or health authority.

Addendum E. TEACHER OBSERVATION CHECKLIST
 
Teachers, more than anyone else, see the student when he or she is trying to achieve. Your observations will be an important part of the vision screening program. Please check below any of the signs or symptoms you observe in your students.

Student’s Name                                                                                

Grade:                                               
Appearance of the Eyes:
1. Eyes crossed – turning in or out at any time
2. Reddened eyes or lids
3. Watering eyes
4. Encrusted eyelids
5. Frequent styes

Behavioral Indications of Possible Vision Difficulty:
1. Body rigidity while reading
2. Thrusting head forward or backward while looking at
distant objects
3. Avoiding close work
4. Short attention span
5. Turning of head so as to use one eye only
6. Placing head close to book/desk when reading or writing
7. Frowning or scowling while reading or writing
8. Excessive blinking
9. Tending to rub eyes
10. Covering or closing one eye
11. Dislike for reading
12. Unusual fatigue after completing a vision task
13. Losing place while reading
14. Using finger or marker to guide eyes
15. Saying the words aloud or lip reading
16. Moving head rather than eyes while reading

Complaints Associated with using the eyes:
1. Headaches
2. Nausea or dizziness
3. Burning or itching of eyes
4. Blurring of vision at any time
5. Words or lines running together