Normative Data for Visual Function Tests in Young Children
abstract
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Access this abstract now Full Text Available for ClinicalKey SubscribersObjective
To provide the normative pediatric data for three tests of functional vision.
Design
Prospective, cross-sectional study.
Participants
The participants were 281 children between 3 and 5 years of age (mean 4.2 ± 0.8 years) participating in a preschool vision screening study.
Methods
Participants completed monocular testing with the Precision Vision Visual Acuity Testing (PVVAT) system, a computerized test of visual acuity. Stereoacuity was assessed using the Pass Test 3 Stereo Test. Noncycloplegic refractive error was measured using the Plusoptix S09 Vision Screener (PS09). The mean and 95% tolerance limits were determined for each test.
Results
Visual acuity improved significantly from 0.31 logMAR at 3 years to 0.18 logMAR at 5 years (p < 2.4 × 10−15). Stereoacuity improved from 104 arcsec at 3 years to 81 arcsec at 5 years (p = 0.0058). Spherical refractive error remained relatively stable at 0.29 D at 3 years and 0.24 D at 5 years (p = 0.543). Cylindrical refractive error was also relatively stable, measuring 0.39 D at 3 years and 0.31 D at 5 years (p = 0.109).
Conclusions
Both visual acuity and stereoacuity improved significantly from 3 to 5 years of age. Note, however, that the norms obtained using the PVVAT system were somewhat lower than those reported in previous studies using other tests. The norms for the PS09 were stable and showed relatively good agreement with the manufacturer-suggested referral criteria.
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Drover et al recently reported a study providing normative data on three tests of visual function (Precision Vision Visual Acuity Testing [PVVAT] system, the Pass Test 3 stereo test, and the PlusoptiX S09 [PS09] Vision Screener) in children ages 3 to 5 years from St. John, Newfoundland, Canada. As other studies have found, both visual acuity and stereoacuity improve significantly over that short period of time, and the norms for the PlusoptiX showed good agreement with manufacturer’s suggested criteria. The PVVAT results were lower than the results reported in other studies employing the LEA SYMBOLS or HOTV letters, potentially due to there being five optotypes with the PVVAT versus four for the other visual acuity tests, or perhaps due to somewhat different design elements. This would require different cutoffs for acuity with this particular test than the two others for screening purposes, as the authors state.
The results for the PlusoptiX are, in my view, more difficult to interpret as we have no data provided directly comparing these measures with those of a cycloplegic refraction, and 55 children were excluded from data analysis who failed the gold standard exam; so, it is not clear to me exactly what these data actually mean. How do they relate to the true cycloplegic refractive error? We know that the comparison between the two is very imprecise, especially for those children with moderate to high hyperopia.
In addition, as we know from a number of studies in the US, variations exist among racial, ethnic, and socioeconomic groups. We have no information about this in the paper, but likely the children were relatively more homogeneous (specifically, more Caucasian) than in a typical US urban-based study. Nonetheless, this study does provide useful information about functional test norms in the preschool population.