A pseudoisochromatic test of color vision for human infants.

Despite the development of experimental methods capable of measuring early human color vision, we still lack a procedure comparable to those used to diagnose the well-identified congenital and acquired color vision anomalies in older children, adults, and clinical patients. In this study, we modified a pseudoisochromatic test to make it more suitable for young infants. Using a forced choice preferential looking procedure, 216 3-to-23-mo-old babies were tested with pseudoisochromatic targets that fell on either a red/green or a blue/yellow dichromatic confusion axis. For comparison, 220 color-normal adults and 22 color-deficient adults were also tested. Results showed that all babies and adults passed the blue/yellow target but many of the younger infants failed the red/green target, likely due to the interaction of the lingering immaturities within the visual system and the small CIE vector distance within the red/green plate. However, older (17-23 mo) infants, color- normal adults and color-defective adults all performed according to expectation. Interestingly, performance on the red/green plate was better among female infants, well exceeding the expected rate of genetic dimorphism between genders. Overall, with some further modification, the test serves as a promising tool for the detection of early color vision anomalies in early human life.

Comparison of Patti Pics and Lea Symbols optotypes in children and adults.

PURPOSE: Although a great variety of pediatric tests of visual acuity exist, few have been compared directly within the same patients or have been evaluated directly against an adult gold standard. METHODS: Right eyes from 80 3- to 5-year-old preschoolers were tested at 3 m with the two current pediatric optotype tests-the Patti Pics and the Lea Symbols (Mass VAT versions)-that best adhere to the international standard for early eye and vision screening. For comparison, right eyes from 52 adults were tested under the same conditions with both pediatric tests and with a gold standard Mass VAT Sloan letter test. RESULTS: Compared with the Patti Pics, both children and adults showed relatively better and finer levels of visual acuity with Lea Symbols (0.07-0.11 logMAR better). Compared with Sloan letters, adults' acuity was also 0.09 logMAR better with the Lea Symbols but was virtually identical and also showed good statistical agreement with Patti Pics acuity. CONCLUSIONS: Although both pediatric tests show excellent testability, our data suggest that acuity values obtained with the Patti Pics optotypes are more consistent with those obtained with a gold standard visual acuity test used for older children and adults.

Children with fetal alcohol spectrum disorder show an amblyopia-like pattern of vision deficit.

AIM: The aim of the study was to assess and characterize visual functioning in children with fetal alcohol spectrum disorder (FASD) using a broader and more inclusive range of measures than has been reported previously. METHOD: Standard tests of visual functioning were used to assess 21 children (11 females, 10 males) with FASD and 21 sex- and age-matched comparison children without FASD. The age of the children ranged from 6 years 9 months to 11 years 11 months (mean 9y 6mo). Children were tested individually under standardized conditions for visual acuity, stereoacuity, contrast sensitivity, ocular alignment/motility, color vision, and refractive error. RESULTS: Compared with non-affected children, children with FASD showed deficits in visual acuity, contrast sensitivity, and stereoacuity. Ocular alignment/motility, refractive error, and color vision measures were normal. Among children with FASD, 62% met the criteria for referral to an eye specialist, compared with 20% of children without FASD. INTERPRETATION: Children with FASD showed an amblyopia-like pattern of vision deficit in the absence of the optical and oculomotor disruptions of early experience that usually precede this condition. Evidence from animal models suggests that the deficits in spatial vision may be due to alterations in the functional architecture of the neocortex that occurs following prenatal alcohol exposure.

Prevalence of amblyopia and other vision disorders in young Newfoundland and Labrador children.

BACKGROUND: Currently, there is a lack of adequate data on pediatric eye and vision disorders in Canada, particularly in the province of Newfoundland and Labrador. In the present study, we estimate the prevalence of eye and vision disorders among young children who participated in a vision screening program in the St. John's, Newfoundland, metropolitan region. METHODS: In daycare settings, 946 children (mean age 4.2 years) were screened with the latest tests of optics and functional vision. Those with suspected vision disorders were referred to an optometrist for a complete eye examination. From the results of these examinations, prevalence rates were estimated for several categories of vision disorders. RESULTS: Overall, we estimate that 14.0% of the children possessed significant vision disorders, the most prevalent of which were hyperopia, amblyopia, and strabismus (4.8%, 4.7%, and 4.3%, respectively). Myopia and anisometropia, on the other hand, were relatively rare (1.1% and 1.4%, respectively). In general, prevalence estimates are within the range of existing estimates from other developed nations. INTERPRETATION: Although the prevalence rates reported here must be interpreted cautiously because of methodological limitations, it appears that children in the present study do not possess an abnormally high prevalence of visual dysfunction. Nevertheless, because an estimated 14.0% of children tested had treatable vision disorders, early screening is clearly warranted in Newfoundland and Labrador.

Accuracy of the contrast sensitivity card test for infants: retest variability and prediction of spatial resolution.

PURPOSE: We assessed the retest variability of a new contrast sensitivity (CS) card procedure and its ability to predict spatial resolution. METHODS: Twenty-four 3-month-olds were tested twice with the CS cards and once with the Teller acuity cards (TAC) within a single session. RESULTS: Coefficient of repeatability (COR) analysis revealed that retest variability of the new cards is superior to that of an earlier prototype at low to mid spatial frequencies. Furthermore, retest variability is comparable to that of infant visual evoked potential studies and the Vistech 6500, a chart commonly used to measure CS in adults. Finally, estimates of visual acuity based on the CS cards were consistent with those provided by the TAC (although CS-based estimates were generally lower overall). CONCLUSIONS: Given its reliability and accuracy, the new CS card procedure has good potential as a clinical tool for assessing spatial vision in infants and toddlers.

Long-term visual pathology in children with significant perinatal complications.

Eye research in infants who experience significant perinatal complications has been restricted to evaluation of structural ocular disease and spatial vision, and results show that these aspects of vision are at increased risk for abnormal or delayed development. To expand upon previous work, a battery of 17 vision tests was employed to assess, comprehensively, long-term outcome of functional vision. Seventy-six children (38 males, 38 females), between the corrected ages of 2 years 11 months and 10 years 2 months (mean 6y 6mo) with various significant complications (e.g. very preterm birth, bronchopulmonary dysplasia, intraventricular hemorrhage) were compared to normally developing, age-matched control children (n = 61; mean age 7y 1mo) on measures of visual acuity, contrast sensitivity, stereoacuity, peripheral vision, color vision, astigmatism, and binocular alignment. Results showed that at-risk children had more test results that fell within the suspect or abnormal range. At-risk children also had a slightly higher incidence of ocular disorders (e.g. strabismus) and refractive error. These data imply that children who experienced significant perinatal risk factors are at risk for long-term deficits of functional vision. However, most of these deficits appear to be relatively mild.

A double-masked, randomized control trial of iron supplementation in early infancy in healthy term breast-fed infants.

OBJECTIVES: To test whether iron supplementation affects hematologic, biochemical, and developmental status in term breast-fed infants. STUDY DESIGN: Term breast-fed infants (n=77) were randomly selected to receive either 7.5 mg per day of elemental iron as ferrous sulfate or placebo from 1 to 6 months of age. Investigators and families were unaware of group assignment. Complete blood count and ferritin, red cell superoxide dismutase, catalase, plasma ferric reducing antioxidant power, and zinc and copper levels were analyzed at 1, 3.5, 6, and 12 months of age. Bayley mental and psychomotor developmental indexes (MDI and PDI) and visual acuity (with the use of Teller acuity cards) were assessed from 12 to 18 months of age. Analysis performed by analysis of variance and t tests was by intention to treat. RESULTS: Iron supplementation resulted in higher hemoglobin and mean corpuscular volume at 6 months of age and significantly higher visual acuity and PDI at 13 months of age (100+/-12 vs 93+/-9 [+/-SD]). Treatment and placebo groups did not differ in anthropometric indexes, compliance, biochemical status, or demographic characteristics. CONCLUSIONS: Iron supplementation of breast-fed infants appears safe and might have beneficial hematologic and developmental effects for some infants.

Testing young infants with the Welch Allyn suresight non-cycloplegic autorefractor.

Both eyes of 74 healthy 2-12-month-old human infants were refracted twice with the new Welch Allyn SureSight non-cycloplegic autorefractor. At least one reliable estimate of sphere and cylinder was obtained from both eyes of all babies attempted, and 88% of infants contributed two estimates from each eye. These measurements were collected in less than 2 min. Although spherical estimates changed little over the first year (mean = +1.78 D), cylindrical error appeared to decrease from a mean of about 1.4 D (at 6 months) to 0.9 D (at 12 months). Refractive estimates and variability agreed well with published infant data obtained with traditional cycloplegic retinoscopy. Repeatability was excellent for measurement of cylinder but for sphere, 17% of infants' estimates differed by at least 1.0 D between tests. However, given its simplicity and time-efficiency, the SureSight should be a good candidate for the relatively easy screening of significant refractive error in non-verbal paediatric patients.

Using a single test to measure human contrast sensitivity from early childhood to maturity.

Despite the emerging scientific and clinical importance of measuring human contrast sensitivity (CS), developmental data are sparse, especially those obtained with a single methodology. We used a new, time-efficient, psychophysical card procedure to evaluate binocular CS in groups of 20 4- to 9-yr-olds and 10 adults. Combined with data from infants and toddlers obtained previously with the same method, our results show that CS is adult-like by 9 years of age. However, the pattern of development is asymmetrical across spatial frequency (SF): Sensitivity at high SF (which is very poor near birth) shows dramatic improvement over the first three years, but sensitivity at low SF shows much more gradual development, a result which may be explained by differences in the maturation of the underlying neural SF channels. Also notable is that the method shows clinical potential due to its relative speed, ease of use, and consistent results across such a broad age range.

Improving the effectiveness of the infant contrast sensitivity card procedure.

Based on results from an earlier prototype, custom software and printing techniques were developed to construct a new card-based test of contrast sensitivity (CS) for nonverbal subjects. Compared with the prototype, the new CS card test contains three improvements: (1) larger, more salient test gratings; (2) higher contrast warm-up cards for each spatial frequency set; and (3) smaller contrast step size between adjacent cards. The success of the new cards was evaluated by testing 3.5- and 12-month-old human infants. Results indicated that the new version of the test required little time to complete (mean, 6.5 min) and provided accurate estimates of visual acuity. Also, group contrast sensitivity functions (CSFs) showed substantial development from 3.5 to 12 months of age. Surprisingly, however, group CSFs obtained with the new cards were lower than those obtained with the prototype, a discrepancy that may be due to differences in space average luminance between the two sets of cards. In all, the new CS card procedure possesses several merits that give it potential as an option for assessing spatial vision in infants, toddlers, and subjects with multiple impairments.