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Vision screening of 4-year-old children in Singapore
H C Lim1, B L Quah, V Balakrishnan
1Bedok Polyclinic, Family Health Service, Ministry of Health. Hai Chiew LIM/MOH/SINGOV@SINGOV
Insights
Visual acuity screening for 4-year-olds is feasible. Setting the referral criteria at 6/12 for visual acuity improves detection rates and reduces unnecessary referrals for preschool children.
Area of Science:
- Ophthalmology
- Public Health
- Pediatrics
Background:
- Early detection of visual impairments in preschool children is crucial for timely intervention.
- Existing visual acuity screening programs may require optimization for effectiveness and efficiency.
Purpose of the Study:
- To assess the feasibility of an enhanced visual acuity screening program for 4-year-old children in Singapore.
- To establish appropriate referral criteria and evaluate referral outcomes.
- To determine the effectiveness of visual screening in identifying vision problems.
Main Methods:
- A cohort of 450 children aged 4 to 4.5 years underwent visual acuity and stereotests.
- Referral criteria included visual acuity of 6/9 or worse, failed stereotest, strabismus, or untestable results.
- Referral outcomes were assessed by ophthalmologists.
Main Results:
- Screening success rates were high (82.7% for visual acuity, 91.6% for stereotest).
- Refractive errors (35.0%) and amblyopia (4.4%) were common findings among referred children.
- Adjusting the visual acuity referral threshold to 6/12 decreased the referral rate while improving positive predictive value and maintaining detection of amblyopia.
Conclusions:
- Visual acuity screening is feasible for 4- to 4.5-year-old children.
- A referral criterion of 6/12 for visual acuity is recommended for improved program efficiency.
- Further evaluation is needed for the utility of the Frisby stereotest in this age group.
Aim Of The Study:
To evaluate the feasibility of an improved visual acuity screening program for Singapore 4-year-old preschool children and to draw up an appropriate referral criteria as well as evaluating the rates and outcomes of these referrals.
Method:
A total of 450 children aged 4 to 4 1/2 years, who attended 3 polyclinics of the Family Health Service (FHS) for their 4-year-old Developmental Health Screening during the study period from 1/4/1997 to 30/6/1997 were recruited for the study. Children who were tested with Snellen (or Sloan) visual acuity chart resulting in visual acuity of 6/9 or worse, or failed to pass the 3 mm medium plate at 30 cm distance (300 seconds of arc) in the Frisby Stereotest, or were found to have strabismus, or were untestable in either visual acuity test or stereotest were offered referral to ophthalmologists in the hospitals for specialist assessment.
Result:
82.7% of the 450 children were successfully screened with Snellen (or Sloan) chart while 91.6% were successfully screened with Frisby Stereotest. In all, 180 children were evaluated by ophthalmologists. Majority of the children were referred because of their abnormal visual acuity test while only 2 children were referred for failing stereotest alone. Among the 180 children referred, 63 (35.0%) were found to have refractive errors for which spectacles were prescribed. Eight children had amblyopia and 2 children had strabismus which were not detected at the polyclinic screening. The untestable children evaluated had significantly higher abnormality rate (37.5%) than that of children who had 6/9 vision (8.8%) therefore they should be offered referral for further evaluation. There was high "refused referral" rate of 39.0%. Parents of children who were untestable or had 6/9 vision were found to be more likely to refuse offer of referral. If these two groups of children were excluded, the "refused referral" rate dropped to 13.3%. When the referral criteria for visual acuity was reset at 6/12 instead of 6/9, the referral rate dropped from 39.6% to a more manageable 26.7% and the positive predictive value improved from 35.4% to 48.3% and none of the children with amblyopia were missed being screened-out.
Conclusion:
The study confirmed the feasibility of doing visual acuity screening at 4 to 41/2 year-old. The referral criteria for abnormal visual acuity should be set at 6/12. The efficacy of adding Frisby stereotest needs further evaluation.