The purpose of this article is to provide recommendations for screening children aged
36 to younger than 72 months for disorders of the eyes and visual system, primarily
amblyopia, strabismus, significant refractive error, and risk factors associated with
these disorders. The screening may be performed in educational-, community-, or public
health–based settings or in the medical home using recommended methods that are appropriate
for the screening venue. The tests recommended herein are intended for vision screenings
conducted by lay screeners, school nurses, and other screening personnel in public
health settings, primary health care practices, or the child’s medical home to identify
children in need of further evaluation by an eye care professional.
This article describes best practices supported by available research evidence, as
well as acceptable standards for the conduct of vision screening in children aged
36 to younger than 72 months. Using best practice standards should be the goal for
all vision screening programs.
RATIONALE FOR VISION SCREENING
Amblyopia and its primary risk factors, strabismus and significant refractive error,1,2
are the most common visual disorders in preschool children.3 The prevalence of amblyopia
among children aged 36 to younger than 72 months in the United States is about 2%.4–6
Strabismus, a contributor to amblyopia and a disorder with significant psychosocial
consequences,7,8 has an estimated prevalence of 2.1 to 3.6% in preschool children.4–6
The prevalence of significant refractive error, a condition more widespread than amblyopia
and strabismus combined, is dependent on race/ethnicity, age, and the type of refractive
error and criterion used to define the magnitude considered significant.9–13 For example,
recent population-based estimates in a multiethnic cohort of children aged 6 to younger
than 72 months found the prevalence of hyperopia greater than or equal to 2.00 diopters
(D) and astigmatism greater than or equal to 1.50 D in Hispanic children to be 26.9
and 16.8%, respectively, whereas the prevalence in African American children was 20.8%
for hyperopia and 12.7% for astigmatism.9,11,12 Not all of these children, however,
have amblyogenic refractive error or refractive error significant enough to warrant
an optical correction. The US Preventive Services Task Force (USPSTF) recommends that
children between the ages of 3 and 5 years be screened at least once to detect the
presence of amblyopia and amblyogenic risk factors such as strabismus and significant
refractive error.3
Whereas vision screening is typically easier in school-aged children 6 years and older,
evidence suggests that the success of amblyopia treatment is influenced by a child’s
age, with children younger than 7 years old being more responsive to amblyopia treatment.14
The recent USPSTF report concluded that there is adequate evidence that early treatment
of amblyopia results in improved visual outcomes.3 In addition, optical correction
of significant refractive error may be related to child development15 and may improve
school readiness.16,17 The USPSTF recommends that children undergo vision screening
at least once between the ages of 36 and 72 months instead of waiting until children
are school-aged. Ongoing and periodic vision screening during the school years, however,
is also important for school-aged children not receiving comprehensive eye examinations
because refractive errors and other visual disorders may develop during this time.
Recommendation Development
In 2009, the Maternal and Child Health Bureau, recognizing the importance of early
vision and eye health, funded the establishment of the National Center for Children’s
Vision and Eye Health at Prevent Blindness. A National Expert Panel (NEP) composed
of leading professionals in ophthalmology, optometry, pediatrics, public health, and
related fields was formed to advise the Center on how best to improve the public health
infrastructure supporting the early detection of children’s vision problems. The NEP
specifically addressed vision screening methodology and the system of care needed
to ensure appropriate, subsequent referral for professional eye evaluation and management.
The NEP undertook a literature review (through February 2014) of the evidence base
underlying vision screening of children aged 36 to younger than 72 months, supplementing
their evaluation of the literature with the group’s clinical experience where necessary.
The rationale and process used to develop the recommendations are fully described
in the Appendix, available at http://links.lww.com/OPX/A187. Screening methods designated
herein as “best practice” are considered to have a sufficient evidence base from well-designed
and well-conducted vision screening studies of children aged 36 to younger than 72
months to support their use in the educational, community, public health, or primary
health care environments. Methods considered to be “acceptable practice” have some
peer-reviewed published literature, but an insufficient level of evidence for the
best practice categorization, generally because of small sample size, flaws in study
design, or limited generalizability to the targeted age group or mass vision screening
environment.
The NEP has written three reports targeting children aged 36 to younger than 72 months
with recommendations for (1) conducting quantitative vision screening, (2) building
an integrated data system to track vision screening and subsequent eye care,18 and
(3) specifying recommendations for developing state-level performance measures to
track progress toward the goal of providing high-quality vision screening and follow-up
to all preschool-aged children.19
This document is the first of the three reports and provides vision screening recommendations
for children aged 36 to younger than 72 months that incorporate best practices based
on currently available evidence. These practices should be reviewed periodically,
at least every 5 years, with revised information available on the Web site for the
National Center for Children’s Vision and Eye Health (http://nationalcenter.preventblindness.org).
Children Requiring Automatic Referral for Examination
Children at high risk for vision disorders and those with readily recognized eye abnormalities
such as strabismus or ptosis should be referred directly, and in a timely manner,
to an appropriate eye care professional. Because children with known neurodevelopmental
disorders (e.g., hearing impairment, motor abnormalities such as cerebral palsy, Down
syndrome, cognitive impairment, autism spectrum disorders, or speech delay) have a
higher rate of vision problems than those without neurodevelopmental abnormalities,20–24
they should be referred directly to an optometrist or ophthalmologist for a comprehensive
eye examination. Children with systemic diseases or using medications known to cause
eye disorders, those with a family history of a first-degree relative with strabismus
or amblyopia, and children born prematurely at less than 32 completed weeks of gestation
also should receive a comprehensive eye examination rather than be screened.2,25–27
Additionally, when a parent or guardian believes his or her child may have a vision-related
problem, an eye care professional should examine that child. Because the purpose of
vision screening is to identify children in need of further care, those who have received
a comprehensive eye examination from an eye doctor within the previous 12 months do
not need to be screened but should be referred back to their eye doctor for follow-up.
VISION SCREENING PROCESS
In general, there are two vision screening approaches (Table 1) for children aged
36 to younger than 72 months, each with advantages and disadvantages. The first method
is a monocular measure of recognition visual acuity using an age-appropriate technique.
The alternative approach is to use instrument-based screening methods (autorefraction
or photoscreening) to identify amblyogenic risk factors, particularly significant
refractive error.29 All screening personnel should undergo a comprehensive training
program, preferably with standardized training and certification in the screening
methods to be used, with subsequent continuing education and formal recertification
every 3 to 5 years. Tests such as red reflex testing for media opacity detection or
cover testing for eye misalignment should only be used as part of the vision screening
process if administered by health care personnel professionally trained to perform
and interpret the tests. When performed alone, neither test provides sufficient information
for a full vision screening,30,31 although detection of an abnormality should trigger
referral for a comprehensive eye examination.
TABLE 1
Best practices for vision screening children aged 36 to younger than 72 months
Selecting the vision screening method to be used depends on the screening venue, availability
of screening personnel, time allotted for the screening, and funding resources. Ideally,
a vision screening program should consist of a single cost-effective test that can
be quickly and easily administered by nonmedical personnel to the target population
in any environment. Significant training should not be required; the child’s cooperation
should not be essential; missed referrals and unnecessary referrals should be nonexistent;
and the screening results should automatically be integrated into an electronic health
record. Any real-world screening method represents a trade-off among all of these
factors. Screening programs can be designed to use a single screening test or a combination
of more than one test. However, combining two screening tests does not necessarily
result in the highest sensitivity and specificity from each component test.32 The
strengths and weaknesses of currently available vision screening methods are described
below.
Recognition Visual Acuity Screening
Visual acuity is the quantifiable measure of the ability to identify black symbols
on a white background at a standardized test distance. The most commonly measured
type, recognition visual acuity, is defined as the ability to discern certain optotypes
(letters, numbers, or figures) at a specified distance. Ideally, tests of visual acuity
should have the same number of optotypes for each acuity level and the same proportional
decrease in size from one acuity level to the next smaller level in logMAR (logarithm
of the minimum angle of resolution) progression.33
Visual acuity methods for vision screening are widely used for adults and school-aged
children. To be performed reliably in children aged 36 to younger than 72 months,
however, a number of testing modifications are required (Table 2).34,35 These include
using age-appropriate and adequately illuminated test symbols that can be presented
in random order and using a lap card (i.e., card with the test optotypes that the
child places on his or her lap) for matching, administering a pretraining or demonstration
session before the start of testing to confirm that the child understands and can
perform the test, and using a closer test distance. Ideally, the test environment
should be quiet and free of distraction, the wait time short, and the child approached
in a manner that maximizes his or her cooperation (such as presenting the screening
task as a game rather than as a test). The parents and/or teachers of the child to
be screened should be fully informed about the importance of vision screening and
ideally be provided with practice cards to be used before screening.
TABLE 2
Distance visual acuity testing for vision screening of children aged 36 to younger
than 72 months
Testing Symbols
The HOTV36,37 and LEA Symbols,38 two tests that were developed for use in preschool
children,35,39,40 are presently considered best practice for visual acuity testing
of children aged 36 to younger than 72 months. The letters H, O, T, and V have vertical
symmetry, and the LEA Symbols consist of four picture optotypes (house, heart/apple,
circle, and square) that blur equally.38 Although 3-year-old Head Start children have
been reported to achieve better visual acuity scores with the LEA Symbols, no statistically
significant differences in sensitivity between the tests were found for 3-, 4-, or
5-year-old children.41 While HOTV optotypes are used more commonly in preschool-aged
epidemiological studies4,42–44 and randomized clinical trials for amblyopia,45–47
most children 3 years and older can successfully complete visual acuity testing using
either set of optotypes.48
Snellen optotypes are not recommended for the measurement of visual acuity in preschool-aged
children. Children this age do not know their letters sufficiently well and the letters
are not equally detectable. Because Landolt C and Tumbling E tests require discrimination
of left-right directionality (rightward vs. leftward pointing), a skill that is not
sufficiently developed in preschool children,49 these tests should also not be used.
Picture charts, such as the Allen Preschool Vision Test and the Kindergarten Eye Chart,
are also problematic because they are not standardized. Both have variable interline
gap widths and shape cues resulting in some of the pictures being more readily identified
than others.35 When pictures are too easily recognized, visual acuity is overestimated
in children with amblyopia.34,50,51 Furthermore, some of the pictures have a cultural
bias and others are outdated, making the pictures not readily recognizable by all
children.
Symbol Presentation and Crowding Bars
When a small number of optotypes such as the HOTV or LEA Symbols are used in testing,
the possible responses are limited. On any presentation of four letters, the probability
of guessing three of four optotypes correctly is about 5%.45 Thus, any given visual
acuity level is considered to be passed if three of three or three of four optotypes
are correctly identified at that particular level. Although the presentation of single
optotypes generally improves testability, the use of single isolated optotypes substantially
reduces the sensitivity for the detection of amblyopia.52 Surrounding single optotypes
with four flanking bars that create a “crowding effect” improves amblyopia detection.53,54
Isolated HOTV or LEA optotypes with crowding bars presented in printed format or by
computer have been used successfully in large-scale studies of preschool children5,28,44–46
and are considered best practice for measuring visual acuity in children aged 36 to
younger than 72 months. A single line of optotypes with crowding bars on all four
sides extended to form a crowding rectangle surrounding the line of optotypes48 is
also preferable to isolated optotypes without crowding bars; this type of presentation
is considered acceptable practice.
Occlusion for Visual Acuity Testing
Visual acuity testing should be conducted separately for each eye because unilateral
amblyopia is masked by the better-seeing eye when amblyopic children are tested binocularly.
Screening personnel need to monitor occlusion carefully because children with reduced
vision in one eye often attempt to use their better eye by peeking. Preferred methods
of occlusion are to use adhesive eye patches or 2-in wide hypoallergenic surgical
tape (e.g., Micropore or Blenderm). An acceptable method is the use of specially constructed
occluder glasses (e.g., Good-Lite opaque occluder glasses). Holding a tissue, hand,
paper cup, or an occluder paddle over a child’s eye is not acceptable because children
can easily circumvent these types of occlusion.
Testing Distance
The optimum test distance for measuring visual acuity in children aged 36 to younger
than 72 months is shorter than that used for adults and school-aged children. The
advantages of a shortened test distance include improved ability to maintain the child’s
attention and the ability to test the child in a smaller space, thereby avoiding the
distractions of a crowded hallway or large testing room. The best practice for children
this age is to use single surrounded optotypes at a 5-ft (1.5-m) test distance.28
Significantly increased sensitivity for a given level of specificity, equal to that
obtained by eye doctors, has been found when lay screeners use single surrounded LEA
Symbols at the 5-ft (1.5-m) test distance28 compared with when lay screeners use the
linear LEA test at 10 ft (3 m). Using a test calibrated for a 10-ft (3-m) test distance
is considered acceptable practice34,35; testing distances closer than 5 ft (1.5 m)
should not be used because myopia may be missed. For example, at a test distance of
14 in (33 cm), 3 D of myopia may go undetected. Although 0.50 to 0.75 D of myopia
may be masked at the 5-ft (1.5-m) test distance, this small magnitude does not meet
the typical referral guideline for preschool myopic refractive error. Thus, test distances
greater than 10 ft (3 m), the use of near cards, or vision testing devices that optically
simulate distance vision (such as those used at many motor vehicle testing facilities)
do not meet the recommended minimum standards for measuring visual acuity in children
aged 36 to younger than 72 months. Screening programs that are still using cards calibrated
for 10 ft (3 m) should begin moving toward the best practice of testing visual acuity
at 5 ft (1.5 m), which will require replacement of equipment.
Illumination of Test Materials
Visual acuity testing is best performed with good illumination and maximum contrast
(at least 85%) between the black symbol and the white background.55 Best practices
for illumination are using a lightbox with a translucent visual acuity chart, a lighted
stand designed to hold and evenly illuminate the acuity test, or a computer screen
display. Insufficient illumination of the test material (<80 cd/m2)55 and competing
light sources that create glare or uneven illumination (e.g., testing performed beside
a window) should be avoided because they can negatively affect visual acuity measurements.
Pass/Fail Criteria for Visual Acuity Testing
The passing criterion for HOTV or LEA Symbols is age specific and must be met by both
the right and left eyes separately. Children aged 36 through 47 months must identify
correctly three of three or three of four of the 20/50 (5/12.5) optotypes to pass;
children aged 48 to younger than 72 months must correctly identify the same number
of optotypes at the 20/40 (5/10) level.4,5,30 Children who do not meet these age-specific
criteria for each eye should be referred for a comprehensive eye examination.
Instrument-Based Vision Screening
Instrument-based screening refers to vision screening using automated technology.
Generally, instrument-based screening is quick to administer and requires minimal
cooperation from the child, thereby making it especially useful for shy, noncommunicative,
or preverbal children. Using an automated instrument also offers the advantage of
having the potential for the screening results to be integrated directly into a data
management system without requiring manual data entry. A recent policy statement published
by the American Academy of Pediatrics noted that an instrument-based approach can
be used in the medical home as an alternative to visual acuity screening for children
aged 3 through 5 years.29
Refractive Instrument-Based Methods of Vision Screening
Instrument-based screening using autorefraction or photorefraction/photoscreening
identifies the presence and magnitude of refractive error rather than providing a
measurement of visual acuity. Each of these screening devices requires instrument-
and age-specific pass/fail refractive error criteria. Abnormal refractive error is
a significant risk factor for amblyopia.2 Hyperopic refractive error greater than
or equal to 2.00 D spherical equivalent, in particular, is associated with a significantly
higher risk of esotropia,26 which by itself is an additional risk factor for amblyopia.
Because of the association among amblyopia, strabismus, and uncorrected significant
refractive error, screening for refractive error alone is often successful in identifying
children with constant strabismus and moderate to severe levels of amblyopia.28,30
Autorefraction
Autorefractors are computerized instruments that use optically automated skiascopy
methods or wave-front technology to provide a numeric estimate of refractive error.
When used for vision screening purposes, the operator or the instrument must interpret
the refractive error measurement as a pass or fail. Although accurate determination
of refractive error (hyperopia in particular) requires the instillation of eye drops
to provide cycloplegia, eye drops are not used in the screening environment. Accordingly,
vision screening by autorefraction only provides an estimate of refractive error;
it is not a substitute for an eye examination and refraction by an ophthalmologist
or optometrist.
Unlike tabletop models that are often difficult to use with young children, handheld
autorefractors are suitable for vision screening because they are portable and only
require a few seconds of a child’s attention. At the time of this publication, two
handheld autorefractors, the Retinomax (Right Mfg Co Ltd, Tokyo, Japan) and the SureSight
Vision Screener (SureSight) (Welch-Allyn, Inc, Skaneateles Falls, NY), have high-quality
published performance data in the targeted age range and are commercially available
with the appropriate Food and Drug Administration designation; thus, they meet the
criteria for best practice for preschool vision screening.28,30 The Vision in Preschoolers
(VIP) Study has shown that these two autorefractors meet or exceed the screening performance
achieved using recognition visual acuity testing in preschool children.28,30
The Retinomax has a high testability rate28,56,57 and good sensitivity at both 0.90
and 0.94 specificity in children aged 36 to younger than 72 months28,30; however,
the results are reported in ophthalmic prescription format, which is not readily interpretable
by most lay screeners. The SureSight, when used in the “child mode,” provides the
operator with a pass or fail determination. Although the manufacturer’s preprogrammed
pass/fail criteria do not perform well in identifying amblyopia and amblyogenic conditions
in preschool children,30 software is available (version 2.24 or 2.25, School Health
Corp, Hanover Park, IL) for the SureSight (when used in minus cylinder format) that
incorporates the better-performing VIP Study pass/fail criteria for 90% specificity.30,58
In addition to refractive error data, an asterisk is displayed on the printout when
a child fails according to the VIP referral criteria, thus facilitating interpretation
of the results for screeners who are not eye professionals. Although there are a number
of prior software versions that have been distributed, the NEP recommends that software
version 2.24 or 2.25 be used for preschool vision screenings when the SureSight is
used.
Photorefraction/Photoscreening
Photorefraction or photoscreening devices use optical images of the eyes’ red reflexes
to provide a simultaneous, binocular estimate of refractive error. In addition, some
instruments have the capability to evaluate ocular alignment and identify media opacities.
Depending on the instrument, the output is interpreted by the operator, a central
reading center, or a computer. Some instruments allow the implementation of user-defined
refractive error criteria to determine the pass/fail cutoffs.
In a large multicenter study that compared various preschool vision screening tests,
the three photoscreening instruments evaluated (MTI Photoscreener, Power Refractor
II, and iScreen Photoscreener) were found to have unsatisfactory sensitivity in detecting
amblyopia, strabismus, and significant refractive error compared with the Retinomax
and SureSight autorefractors.30 Since that time, a number of new or updated photoscreening
devices have been introduced to the market, although none has yet undergone the same
type of rigorous evaluation.
One of these newer instruments, the Plusoptix Photoscreener (Plusoptix, Nuremberg,
Germany), is a binocular device based on the aforementioned Power Refractor II. Considered
by some investigators to hold promise for preschool vision screenings,59 the Plusoptix
provides a simultaneous measure of autorefraction and eye alignment and allows the
user to specify the desired pass/fail criteria. The device also provides a report
containing the child’s name, results, and pass/fail status that can be integrated
into an electronic medical record.
Comparisons of the Plusoptix and clinical examination results in nonscreening settings
have been mixed,59–63 and there are limited results available that apply to a vision
screening environment for children aged 36 to younger than 72 months.64 Investigators
have cautioned that the specificity of the Plusoptix is unacceptably low (37%) for
field use when the manufacturer’s pass/fail criteria are used,65 and while modifications
of these criteria can result in improved specificity without loss of sensitivity,
the ideal refractive error criteria have yet to be determined.65 Of note, consensus-based
refractive error criteria that are thought to place young children at risk for the
development of amblyopia and thereby warrant detection by vision screening66 are based
on cycloplegic refractions; these are not intended to be used as cutoff values for
vision screening instruments that measure noncycloplegic refractive error.67 Despite
these limitations and lack of robust evidence, the NEP’s opinion is that the Plusoptix
instrument appears sufficiently promising to be classed as an acceptable practice
at this time, with the caveat that the optimum refractive error referral criteria
have yet to be determined.65 Thus, when the Plusoptix is used outside of an eye care
setting, consultation with a pediatric eye care professional regarding the best cutoffs
to use for the particular patient population to be screened is advised until evidence-based
refractive error criteria are determined.
There are a number of other commercially available screening instruments that also
lack high-quality published data supporting their use for vision screening children
aged 36 to younger than 72 months. The recommendation of best practice for the Plusoptix
and other screening devices will require validation studies. An ideal validation study
consists of a prospective large-scale vision screening performed by lay screeners
in the field, in which all children who pass and fail the screening also receive a
comprehensive eye examination (including a cycloplegic refraction) from an optometrist
or ophthalmologist masked to the results of the screening. The children screened should
be within the targeted age range and also have a wide variety of vision disorders,
particularly strabismus, amblyopia, and high refractive error. This type of rigorous
assessment is necessary to determine the optimum refractive error referral criteria
for a particular instrument.65 Because autorefractor and photoscreening technologies
are evolving rapidly, recommendations for best practice will likely change with the
availability of additional quality peer-reviewed data and as the natural history of
refractive error and the role of risk factors for the development of amblyopia and
strabismus become more clear.68 Updated information will be found on the Web site
for the National Center for Children’s Vision and Eye Health (http://nationalcenter.preventblindness.org).
Nonrefractive Instrument-Based Methods of Vision Screening
Analogous to auditory evoked brain response methods of newborn hearing screening,
there are computerized systems that assess the integrity and maturation of the visual
system through measurement of the electroencephalographic visual evoked response,69
thereby providing information regarding the functional integrity of the visual system.
Another approach for vision screening that is currently under investigation is retinal
birefringence scanning,70,71 which simultaneously detects both the child’s ability
to accurately align the fovea of each eye to a common point in space and focus each
fovea on that point. At present, there is insufficient evidence to recommend either
of these methods for screening children aged 36 to younger than 72 months over either
visual acuity testing or acceptable instrument-based methods of vision screening.
Stereoacuity Testing for Vision Screening
Stereoacuity (depth perception) testing performed in isolation has not been a fruitful
preschool vision screening method.30 However, when combined with the SureSight Vision
Screener, the Stereo Smile II test has been shown to increase the detection rate of
strabismus (an amblyogenic condition).72 Because two screening tests do not necessarily
result in a higher detection rate as compared with each test alone,32 whether to add
stereoacuity testing is dependent on the goals of the screening program and resources
available. In instances when stereoacuity testing is required or desired for screening
preschool children, the Stereo Smile II test, which is commercially available as the
PASS (Preschool Assessment of Stereopsis with a Smile) test (Vision Assessment Corporation,
Elk Grove Village, IL), should be used because it performs better than the Random
Dot E test of stereoacuity.30 As new research emerges, the role of stereoacuity testing
in combination with other vision screening tests will be reviewed.
Untestable Children and Rescreening Guidelines
Children who are inattentive, are uncooperative, will not allow one eye to be covered
for monocular visual acuity testing, or do not appear to understand the screening
task are not considered to have failed, but instead are deemed “untestable” (Fig.
1). Untestable preschool children are about twice as likely to have a vision problem
than those who successfully pass a screening.73 If practical, untestable children
should be rescreened the same day. When a same-day rescreening is not feasible, rescreening
should be scheduled as soon as possible, but in no case later than 6 months. Because
children unable to be screened with visual acuity testing can often complete autorefraction
testing and vice versa,73 one should consider using the alternate method for rescreening
if both are available. Untestable children with cognitive, physical, or behavioral
issues that are likely to preclude successful rescreening, children who are unable
to be rescreened within 6 months, and those who fail rescreening should be referred
directly for a comprehensive eye examination by an optometrist or ophthalmologist
(Fig. 1).
FIGURE 1
Flowchart for children who receive a vision screening.
COMPONENTS OF A COMPREHENSIVE VISION SCREENING PROGRAM
Vision screening of children aged 36 to younger than 72 months, which is recommended
by the USPSTF,3 can be performed either by measuring recognition visual acuity directly
or by using instrument-based methods of autorefraction or photoscreening to identify
amblyogenic refractive error. Sufficient evidence showing that either method is effective
when the aforementioned best practice testing methods are used has accumulated.28,30
The number of children to be screened, time allotted for screening, available budget
for implementing the screening program, and reporting requirements will be factors
in determining whether a recognition visual acuity–based screening program, an instrument-based
program, or a hybrid of the two is used.
Regardless of the screening method(s) selected and whether the child passes or fails
the vision screening, the screening system is only successful when the results are
used in a meaningful way. Screening results must be recorded and communicated to the
child’s parents, and as appropriate to the medical home/primary care provider, the
school, and necessary state agency, with subsequent referral to an ophthalmologist
or optometrist for examination and care when indicated. Specific data systems must
be established to facilitate this process18 and programs should monitor overall system
performance at the population level to ensure that screening goals are being met.19
SUMMARY OF RECOMMENDATIONS
All children aged 36 to younger than 72 months should be screened annually (best practice)
or at least once (acceptable minimum standard) during the interval between their third
and sixth birthdays. Exceptions to this include children with the following: readily
observable ocular abnormalities, neurodevelopmental disorders, systemic conditions
that have associated ocular abnormalities, first-degree relatives with strabismus
or amblyopia, a history of prematurity (<32 completed weeks), and parents who believe
their child has a vision problem. These children should be referred directly to an
ophthalmologist or optometrist for a comprehensive eye examination. Children who have
received an eye examination from an eye care professional within the prior 12 months
do not need to be screened. A vision screening program based on best practice standards
should be the goal.
Children who are unable or refuse to complete testing are considered untestable. These
children are more likely to have vision problems than testable children,73 and thus
should be rescreened either the same day or soon afterward, but in no case later than
6 months. Children with cognitive, physical, or behavioral issues likely to preclude
rescreening and those unable to be rescreened in a timely manner because of administrative
or other issues should be referred directly for a comprehensive eye examination.
Currently, there are two best practice vision screening methods for children aged
36 to younger than 72 months: (1) monocular vision acuity testing and (2) instrument-based
testing using autorefraction. For visual acuity testing, appropriately scaled (logMAR)
single crowded HOTV letters or LEA Symbols surrounded by crowding bars at a 5-ft (1.5-m)
test distance with the child matching or reading the optotypes aloud should be used.
A passing score is the correct identification of three of three or three of four optotypes
with each eye at the 20/50 level for children aged 36 through 47 months and at the
20/40 level for children aged 48 to younger than 72 months. Acceptable practices are
to use the HOTV or LEA Symbols calibrated for a 10-ft (3-m) test distance or to use
a single line of these optotypes surrounded by a rectangular crowding bar on all four
sides. Other optotypes like Allen pictures and the Tumbling E should not be used.
The other best practice vision screening method is instrument-based screening using
either the Retinomax autorefractor or the SureSight Vision Screener set in child mode
and programmed with the VIP Study pass/fail criteria software for 90% specificity
(version 2.24 or 2.25) in minus cylinder form. Using the Plusoptix photoscreener is
considered acceptable practice, as is adding the PASS stereoacuity test as a supplement
to one of the best practice screening methods.
Vision screening requires training and certification of screening personnel, acquiring
sufficient and appropriate space, obtaining and maintaining equipment and supplies,
as well as recording and reporting the screening results to the family, primary care
provider/medical home, and when indicated the school or appropriate state agency.
A best practice for children who fail vision screening includes documentation of the
referral to and subsequent comprehensive eye examination by an optometrist or ophthalmologist.
A range of resources to support implementation of these recommendations, including
demonstrations of the vision screening process, can be found at http://nationalcenter.preventblindness.org.
CONCLUSIONS
It is the NEP’s intent that this summary will prove useful for eye care professionals
playing a leadership role in ensuring that children aged 36 to younger than 72 months
in their communities receive high-quality vision screening and appropriate follow-up.
Supplementary Material
SUPPLEMENTARY MATERIAL
Susan CotterSouthern California College of Optometry atMarshall B. Ketchum University2575
Yorba Linda BlvdFullerton, CA 92831e-mail: scotter@ketchum.edu