Acuity Norms Research Articles

Study to establish visual acuity norms with Teller Acuity Cards II for infants from southern China

ObjectivesTo establish the norms of binocular and monocular acuity and interocular acuity differences for southern Chinese infants and compare these norms with the results for northern Chinese infants.MethodsA prospective, comparative, and noninterventional study was conducted from January to August 2018. Teller Acuity Cards II were used to determine the binocular and monocular acuity of infants. The tolerance intervals and limits with a stated proportion and probability were used to evaluate the norms of binocular and monocular acuity and interocular acuity differences. An unpaired t-test was used to compare the obtained norms with the reported northern Chinese norms.ResultsThe tolerance intervals of binocular acuity (mean acuity of 3.73, 7.35, and 12.01 cpd, respectively, at 12, 24, and 36 months), monocular acuity (mean acuity of 2.88, 6.91, and 10.75 cpd, respectively, at 12, 24, and 36 months), and interocular acuity differences (mean difference of 0.92, 2.89, and 3.99 cpd, respectively, at 12, 24, and 36 months) were obtained, exhibiting an increasing trend with age. The binocular visual acuity norms of southern Chinese infants were significantly lower than those in northern China (4.37 vs. 6.9 cpd at 8 months and 7.35 vs. 26 cpd at 24 months) (P = 0.011).ConclusionsNorthern and southern Chinese infants exhibited distinct acuity norms and visual development patterns. The establishment of population-specific visual acuity norms is necessary for current populations of infants from different regions.

Different visual development: norms for visual acuity in children with Down’s syndrome

BackgroundVisual acuity is known to be poorer in children with Down’s syndrome than in age‐matched controls. However, to date, clinicians do not have access to norms for children with Down’s syndrome that allow differential discrimination of healthy from anomalous visual development in this population.MethodsThe Down’s Syndrome Vision Research Unit at Cardiff University has been monitoring visual development in a large cohort of children since 1992. Cross‐sectional data on binocular visual acuity were retrospectively analysed for 159 children up to 12-years of age in order to establish binocular acuity norms. Longitudinal binocular acuity data were available for nine children who were seen regularly over the 12-years age‐range. Monocular acuity was successfully recorded less often in the cohort, but analysis of scores for 69 children allowed assessment of inter‐ocular acuity differences and binocular summation.ResultsIn comparison with published norms for the various acuity tests used, binocular acuity was consistently poorer in children with Down’s syndrome from the age of three-years and stabilised at around 0.25 logMAR from the age of four-years. Inter‐ocular acuity difference and binocular summation were both 0.06 logMAR, which is similar to the reported values in children without Down’s syndrome.ConclusionsThe study provides eye‐care practitioners with the expected values for binocular acuity in children with Down’s syndrome and demonstrates the visual disadvantage that children with Down’s syndrome have when compared with their typically developing peers. The results emphasise the responsibility that practitioners have to notify parents and educators of the relatively poor vision of children with Down’s syndrome, and the need for classroom modifications.

Maturation of Binocular, Monocular Grating Acuity and of the Visual Interocular Difference in the First 2 Years of Life.

The sweep visual evoked potential method (sVEP) is a powerful tool for measurement of visual acuity in infants. Despite the applicability and reliability of the technique in measuring visual functions the understanding of sVEP acuity maturation and how interocular difference of acuity develops in early infancy, as well as the availability of normality ranges, are rare in the literature. We measured binocular and monocular sVEPS acuities in 481 healthy infants aged from birth to 24 months without ophthalmological diseases. Binocular sVEP acuity was significantly higher than monocular visual acuities for almost all ages. Maturation of monocular sVEP acuity showed 2 longer critical periods while binocular acuity showed three maturation periods in the same age range. We found a systematic variation of the mean interocular acuity difference (IAD) range according to age from 1.45 cpd at birth to 0.31 cpd at 24 months. An additional contribution was the determination of sVEP acuity norms for the entire age range. We conclude that binocular and monocular sVEP acuities have distinct growth curves reflecting different maturation profiles for each function. Differences in IAD range shorten according to age and they should be considered in using the sVEP acuity measurements for clinical diagnosis as amblyopia.

A new computer-based pediatric vision-screening test.

We developed and validated the Jaeb Visual Acuity Screener (JVAS), a computerized visual acuity-based screening program for children that employs a rapid, age-specific, standardized algorithm for vision screening in the medical home that is available for download at no cost. A total of 175 children aged 3 to <8 (median, 6) years were screened with the JVAS before undergoing a complete eye examination (gold standard). The JVAS presented 2 large single surround optotypes (20/100 and 20/80) and then 5 optotypes at a predetermined, age-specific normal threshold. Failure on the gold standard examination was determined using recently published referral criteria and published visual acuity norms for age. We evaluated the sensitivity and specificity of the JVAS for detecting reduced visual acuity, amblyopia, and amblyopia risk factors. JVAS pass/fail paradigms evaluated were inability to identify 3 of 4, 3 of 5, and 4 of 5 age-appropriate optotype presentations. Screening testability for the JVAS was high, at 100%. Sensitivity of the JVAS ranged from 88% to 91%, and specificity from 73% to 86%, with positive predictive value ranging from 66% to 79% and negative predictive value from 92% to 93% (ranges reflect different pass/fail paradigms). The new JVAS provides an effective and practical method for screening 3- to 7-year-olds using any Windows-based computer. Providing the JVAS free-of-charge to pediatricians and school systems would standardize currently fragmented visual acuity-based screening practices.

Visual Acuity Norms in Pre-School Children: The Multi-Ethnic Pediatric Eye Disease Study

To provide population-based normative data for monocular visual acuity (VA) and interocular differences in VA (IOD) in Black and Hispanic children 30 to 72 months of age without visually significant refractive errors or ophthalmic abnormalities.In a population-based cohort of children in the Multi-Ethnic Pediatric Eye Disease Study, monocular HOTV VA measurements using the Amblyopia Treatment Study protocol were analyzed using continuous and dichotomous outcomes for VA and IOD, after excluding subjects with ophthalmic abnormalities or refractive error.The analysis cohort consisted of 1722 Black and Hispanic children aged 30 to 72 months. Mean logMAR VA improved with age (p < 0.0001) and male gender (p = 0.0008). The proportion of children achieving VA 20/40 or better was associated with age (p < 0.0001), but not ethnicity or gender, and was 81, 94, 99, and virtually 100% in children aged 30 to 35, 36 to 47, 48 to 59, and 60 to 72 months of age, respectively. The most stringent VA threshold that excluded <5% of normal children was 20/63, 20/50, 20/32, and 20/32 for children aged 30 to 35, 36 to 47, 48 to 59, and 60 to 72 months, respectively. Children attending preschool or daycare achieved VA 20/32 more often than those not attending, after age adjustment (p = 0.01), as did children from higher-income families (p = 0.04). There was no association between mean absolute IOD and age (p = 0.45), ethnicity (p = 0.12), or gender (p = 0.19). The proportion of children with an IOD of 0 to 1 lines was higher in males than females (p = 0.02); it did not vary by age (p = 0.06) or ethnicity (p = 0.17). An IOD of 2 or more lines occurred in 6% of normal children.VA test performance in normal pre-school children improves with age. We propose new age-specific thresholds for defining abnormal monocular VA using HOTV optotypes in children between 2 and 5 years of age, for use in screening, clinical practice, and research.

Teller Acuity Card norms with and without use of a testing stage

To determine whether norms obtained using the Teller Acuity Card stage are appropriate for comparison with results obtained when the stage is not used. Eighty children were tested, 20 each at 3.5, 11, 17, and 30 months of age. Binocular grating acuity was measured once with Teller Acuity Cards presented with the stage and once without the stage. Test order was counterbalanced across subjects. Testers were aware that gratings progressed from lower to higher spatial frequencies, but were masked to the absolute spatial frequency of the grating on each card. Testers were masked to acuity results until the child completed testing. Repeated measures ANOVA with age as a between-subjects variable and test setting as a within-subjects variable showed a significant effect of age (p < 0.001) and test setting (p < 0.001), and a significant interaction between age and test setting (p < 0.01). Post-hoc comparisons (with Bonferroni correction) showed that the difference in acuity results obtained with the stage versus without the stage was significant at 17 months (p < 0.05), but not at 3.5, 11, or 30 months. Grating acuity norms obtained with the Teller Acuity Card stage are appropriate for comparison with data obtained without the stage in children 3.5, 11, and 30 months of age. However, when 17-month-old children are tested without the stage, comparison of results with norms obtained with the stage is problematic, because testing without the stage results in reduced acuity scores in this age group.

LogMAR-based visual acuity measurements: limits of normality

Aim: To review critically the literature on the use of logMAR visual acuity tests. This includes visual acuity norms for a range of different ages and tests, and repeatability values. Method: A literature review was conducted of data on validity, age norms and repeatability of currently available logMAR tests. Results: All the methodological discrepancies con­cerning the Snellen-based tests have been accounted for in the design of logMAR-based tests. Tests available for paediatric use include the crowded and uncrowded logMAR test, Kay’s linear logMAR crowded picture test. HOTV acuity test and the l ea Symbols chart. Normative acuity data have been reported for logMAR tests for children from 3 to II years of age and young adults. The data show that with increasing age the mean acuity improves and the range attributed to normal narrows. The repeatabil­ity and reliability of the ETDRS and crowded logMAR tests have been determined and values reported for the detection of change. Conclusions: Research to date remains sparse on visual acuity norms as a function of age for log-based tests and data tend to be on one test for a limited age group. There is a need for comparative age-specific normative data for acuity scores for logMAR tests, which could only he achieved by undertaking a large cohort study evaluating multiple tests on the same children in the age range 3 to 7 years.

Normal visual acuity in 17–18 year olds

The aim of this work was to establish visual acuity norms in 17-18-year-olds. In a previous, population-based study carried out in 1998, a total of 1046 12-13-year-old children were examined with a full eye examination. In 2003, 25% (n=262) of these children were randomly selected and invited to a re-examination; 147 subjects agreed to participate and 116 attended. The examined group did not significantly differ from the original sample in terms of the prevalence of ocular and visual disorders. Best corrected monocular visual acuity (VA) was assessed with the revised 2000 ETDRS logMAR chart. Mean best corrected VA was -0.10 logMAR across the examined group. There was no significant difference between right and left eyes. By excluding nine subjects who had significant ametropia and/or ocular or visual pathology, mean VA increased to -0.12 logMAR (SD 0.07). The mean interocular difference in VA among normal subjects was 0.04 logMAR. Visual acuity in teenagers is significantly better than 0.0 logMAR and the interocular difference is low in healthy eyes.

The Cardiff acuity test used for measuring visual acuity development in toddlers

The Cardiff acuity test was used in estimating the binocular and monocular visual acuity norms of 231 toddlers between 12 and 36 months. Mean binocular acuity increased from 4.5 to 1.2 min arc and monocular acuity from 4.5 to 1.4 min arc over the age range. Interocular acuity difference was not significant and for 99% of the children, the difference in acuity estimate was ⩽ 1/3 octave. Success rates ranged from 96 to 100% for binocular tests but fell to a range of 41–91% for monocular testing. Acuity assessment was fast and the intraobserver reliability was high. Age norms of visual acuity useful in clinical settings are presented for toddlers between the ages of 12 and 36 months.

Natural history of the development of visual acuity in infants

A selective review of the contemporary understanding of development of infant visual acuity is presented together with recent developments in methodology to detect this change. References are confined, wherever possible, to human infant studies relating to factors explaining the development of acuity. Results obtained from a two year study of the development of grating acuity in normal infants are discussed briefly. The findings indicate the importance of establishing acuity norms and sensitivity of interocular acuity difference as an important parameter in the detection of monocular visual deficit in clinical practice.

Visual acuity and stereopsis between the ages of 5 and 10 years. A cross-sectional study.

The development of visual acuity and stereopsis was studied in 321 boys and 340 girls aged between 5 and 10 years. Visual acuity was assessed by the E test and a modified version of the STYCAR test, stereo acuity by the Lang-Stereo test [17]. Both vision tests showed an increase in the median visual acuity between the ages of 5 and 10 years. The E test indicated an increase from 1.2 between 5 and 6 years to 1.5-1.7 between 7 and 10 years. The values obtained with the STYCAR test were 0.6-1.3 higher, depending on the test rating used. Visual acuity norms between 5 and 10 years are presented as empirical centile curves. No significant differences were observed in visual acuity between the left and right eyes, nor between the sexes. The right eye was found to be the leading eye in 54.8% of the boys and 54.5% of the girls (P less than 0.001). The Lang-Stereo test was passed by 87.9%-94.3% of all children, and there were no significant differences with respect to age and sex. Children who failed the test had a significantly lower visual acuity than those who passed it. In the former group a significant interocular difference in visual acuity was present (P less than 0.01).

Visual acuity of the preschool child: a review.

The need for visual acuity assessment in preschool children has long been recognized, yet there are no standardized visual acuity norms or screening criteria. This report reviews the literature on distance visual acuity in the preschool child. The areas of review include: methods of assessment of visual acuity; visual acuity norms obtained with these tests; reasons for the variations in reported visual acuity norms; variations in referral criteria for vision screenings; testability reported for various visual acuity tests; and important design principles and recommendations for preschool visual acuity tests. It is concluded that a well designed preschool visual acuity test should consist of high contrast Snellen optotypes without directional components that progress in 0.1 log steps down to a level of 6/3. To improve testability, a matching or forced choice response should be used. Of the tests that have been standardized, STY-CAR (Sheridan-Gardiner) comes closest to meeting these criteria.

Monocular and binocular acuity estimation in 18- to 36-month-olds: acuity card results.

The acuity card procedure is a useful method for measuring visual acuity in infants 1 to 12 months of age. The results of the present study indicate that the procedure is also a viable method for estimating acuity in children 18 to 36 months of age. Monocular and binocular estimates of acuity were obtained with the acuity card procedure on 36 normal children, 9 each at ages 18, 24, 30, and 36 months. At each of the ages, means and SD's of acuity estimates agreed well with acuity norms from established operant procedures. Mean durations for monocular and binocular estimates averaged 2 to 4 min, and nearly 100% of children were tested successfully both monocularly and binocularly. The flexibility of the required response and the short test times make the acuity cards a promising test of visual acuity in this typically difficult-to-test age range.

Clinical applications of preferential looking measures of visual acuity

We have undertaken 3 lines of research aimed at the eventual transformation of the laboratory-based preferential looking (PL) acuity-testing procedures into clinically-useful techniques. (1) The first line of research involves studies of the parameters of PL testing, and the establishing of norms for various groups. The results show that acuity development is closely tied to gestational age, that infants' acuity is reduced at low luminances but does not vary significantly at levels above 1 log cd/m 2, and that monocular acuity is poorer than previously-published binocular acuity norms. (2) The second line involves the development of a shortened procedure (the ‘diagnostic grating’ procedure) that maximizes the certainty of gaining the most critical information from an infant in a short time. In this procedure, the infant is tested with a low spatial frequency grating to screen for blindness or total lack of visual response, and another grating of a spatial frequency that is diagnostic of normal acuity for children of the patient's age. Based on the results with these two gratings and the time available, the child is then tested with other gratings to refine the acuity estimate. (3) The third line of research involves using the procedure, in a laboratory setting, with individual infants and children at risk for visual acuity deficits. Longitudinal case histories of patients with strabismus, ptosis, and suspected blindness are presented.

Development of visual acuity in infant monkeys ( Macaca nemestrina) during the early postnatal weeks

A forced-choice preferential looking technique was used to assess grating acuity in infant pigtail macaque monkeys. On the average, infants resolved gratings with stripes subtending about 15′, 12′, 8′ and 5′ (2, 2.5, 4 and 6c/deg) in weeks 1, 2, 3 and 5 respectively. Within each age, acuity varied over about 1.5 octaves among individual infants. The data are compared to acuity values found in studies of normal development in human infants. Comparison of the present acuity norms to previous acuity values from dark-reared macaques suggests the possibility that dark-rearing may arrest the development of acuity, but may not disrupt acuity levels established before the onset of dark-rearing.