Canadian Task Force on Preventive Health Care

Full Text Review

Routine Preschool Screening for Visual and Hearing Problems

Prepared by John W. Feightner, MD, MSc, FCFP, Department of Family Medicine, The University of Western Ontario

These recommendations were finalized by the Task Force in March 1994

Up Contents

UpOverview

The 1979 Task Force report concluded that there was no justification for routine screening for visual deficits among asymptomatic individuals, although it did advocate that screening of children and adolescents be continued until better evidence became available. It stated that there was fair justification for physicians to actively identify people with a hearing impairment necessitating further diagnostic study. A subsequent review of the literature to 1988 resulted in changing the recommendation to include testing of visual acuity in the periodic health examination of preschool children based upon fair evidence.< 1> The evidence, however, remained of insufficient quality to recommend the inclusion or exclusion of screening for hearing impairment among non-complainant preschool children.

Consistent with earlier evidence, a 1992 cohort study subsequently showed no benefit attributable to routine pre-school hearing assessment. Considering the resources required for hearing screening, the Task Force does not recommend routine hearing assessment of pre-schoolers although it remains in favour of visual acuity testing.

UpVisual Defects

Up Burden of Suffering

On the basis of data from two Ontario communities, the prevalence rate of visual deficits in the preschool population is estimated to be 10% to 15%. The morbidity rate associated with such deficits depends on the degree of visual impairment and the acceptance of corrective lenses by the patient and by his or her family and peers. Estimates for amblyopia range from 1.2% to 5.6% with similar estimates for strabismus. The prevalence of combined amblyopia and strabismus is estimated to be in the region of 5%.

The identification of poor visual acuity by itself is accepted by many as being clinically important, however, firm evidence is lacking to link poor visual acuity to poor school performance.

Up Maneuver

The use of simple visual charts to test visual acuity has been well developed and is widespread. Concerns have been raised about the need for further testing among preschool children, particularly for amblyopia.

Data on the sensitivity and specificity of the individual visual charts are limited, but instrument performance is far from perfect. Some insight into performance in the clinical setting is provided by evaluating the positive and negative predictive value of screening programs which have incorporated these instruments.

De Becker and co-authors<2> evaluated a program using visual inspection, assessment of visual acuity, and evaluation of stereoacuity. They found a negative predictive value of 98.7% for amblyopia, strabismus, and/or high refractive errors. MacPherson and colleagues<3> evaluated a similar program but with a limited gold standard assessment of outcome. Their findings suggested a positive predictive value of 72%. Kohler and colleagues,<4> in a Swedish population, evaluated a program assessing monocular visual acuity, stereoacuity, and the use of a "cover-test". They found a positive predictive value of 83.5% for all visual acuity problems, but only 43% for visual acuity problems requiring treatment.

Up Effectiveness of Early Detection and Treatment

No randomized controlled trials have evaluated the benefits of screening plus subsequent therapy. Once detected, simple refractive errors affecting visual acuity are readily treatable with eye glasses. However, evidence for the treatment of amblyopia is more controversial and inconclusive. It is widely held that for any potential benefit to be realized, amblyopia must be detected during the "sensitive" period, i.e. between birth and about the seventh year.

One well designed cohort study by Feldman and collaborators<5> examined the effects of preschool screening for visual and hearing problems on the prevalence of such problems six to twelve months later. Visual deficit was defined as an acuity of 20/40 or worse in one or both eyes. At follow-up six to twelve months later, the screened group had 50% fewer visual problems and 75% fewer severe visual deficits than the unscreened group. The impact on school performance, however, was not measured.

Up Hearing Deficits

Up Burden of Suffering

Hearing problems in preschool children are best divided into short-term, transient problems that resolve and persistent problems. The latter category is composed primarily of persistent middle ear effusion and sensorineural deficits. The prevalence of short-term problems is approximately 15% while for persistent problems it is closer to 3%.

Up Maneuver

Tests available to evaluate hearing include clinical assessments such as the "whisper test" and pure tone audiometry. New instruments which evaluate the mobility of the tympanic membrane (tympanometry and acoustic reflexometry) have been used to screen for middle ear effusion, a common cause of transient hearing loss. While pure tone audiometry is often considered a gold standard, its appropriate application requires conditions and equipment which limit its use as a screening method.

The use of tympanometry is becoming more widespread. It requires some patient cooperation and a good seal within the ear canal. Karzon,<6> in a study of preschool children, generated two different sets of test characteristics depending on the criteria used. These test characteristics ranged from a sensitivity of 48% and specificity of 89% under one set of criteria to a sensitivity of 78% with a specificity of 68% using different criteria.

Studies evaluating acoustic reflexometry have indicated varying results. Again, the test characteristics generated depend on the criteria used in the specific studies. Myringotomy to establish the presence of middle ear effusion serves as the usual gold standard. While one study<7> indicated a sensitivity of 93% and the specificity of 83%, another study demonstrated a sensitivity of 88% with a specificity of only 44%.<8>

Up Effectiveness of Early Detection and Treatment

There have been no randomized controlled trials to evaluate the benefit of early detection of hearing problems and subsequent treatment.

However, Zielhuis and co-workers,<9> after screening preschool children with tympanometry for otitis media with effusion, randomized those with this condition to treatment with ventilation tubes or to no treatment. There was no difference between the groups in the main outcome measure of language development, but the authors acknowledge that the number of subjects (43) was quite small. Two additional studies, one a cohort study and another a cohort analytic study, provide valuable data.

Feldman and associates,<5> in a well designed cohort study evaluated hearing in two groups of preschool children, one of which had been screened within the past year, another which had not. Hearing impairment was defined as the inability to hear sounds at 25 decibels in at least two of four speech frequencies. There was no statistically significant difference in the prevalence of hearing deficits between the two groups. The study did not evaluate the impact on school performance.

O’Mara and colleagues,<10> evaluated the outcome of screening 1,653 children aged 3 and 4 years using portable pure tone audiometry over a period of 18 months. 35 children failed the screening test and the results were reported to their parents. Of the 28 children reviewed in follow-up, two were already receiving treatment for hearing problems prior to the study. Eight of the remaining 26 were confirmed to have an underlying clinical problem but 3 of these had already been previously identified. All of the 5 "new problems" (0.3% of the original sample) were caused by middle ear effusion. The authors conclude that their results raise doubts about the potential benefit of such programs.

Up Recommendations of Others

The U.S. Preventive Services Task Force<11> and the American Academy of Family Physicians recommend that all children have testing for amblyopia and strabismus once before entering school, preferably at 3-4 years of age; routine visual acuity testing is not recommended for asymptomatic school-aged children. The American Academy of Ophthalmology, the American Academy of Pediatrics and the American Association for Pediatric Ophthalmology and Strabismus recommend that children have eye and vision screening performed as newborns and at approximately 6 months, 3 years and 5 years of age.

The American Academy of Family Physicians found there was insufficient evidence to recommend for or against universal hearing screening of children. The American Academy of Pediatrics recommends pure tone audiometry at 4 and 5 years of age and the American Speech-Language Hearing Association recommends annual pure tone audiometry for children 3-10 years of age. The recommendations of the U.S. Preventive Services Task Force on screening for hearing impairment are currently under review.

Up Conclusions and Recommendations

There is fair evidence to include testing of visual acuity in the periodic health examination of preschool children.

Two studies speak against including routine hearing assessment in the preschoolage periodic health examination. A cohort comparison study failed to demonstrate benefit of preschool screening. Second, the cohort analytic study of O’Mara and colleagues detected no new hearing problems of a sensorineural etiology after assessing 1,653 children. While hearing screening carries little or no risk to the individual child, it does detract resources (especially time) from other health maintenance maneuvers. This concern plus the lack of demonstrated benefit argue for excluding routine hearing assessment of pre-schoolers from the periodic health exam (D Recommendation).

Up Unanswered Questions (Research Agenda)

Studying the effect that correcting of visual or hearing deficits has on school performance.

Up Evidence

The literature was identified with a MEDLINE search to March 1993 using the following MESH headings or keywords: hearing disorders; vision disorders; child, preschool; mass screening, guideline or Canada. This review was initiated in March 1993 and the recommendation of the Task Force finalized in March 1994.

 Full Citation

Link to Structured Abstract of this review

Link to Summary Table of this review

Link to Selected References list of this review

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