Longitudinal study of acuity and stereopsis in infants with or at-risk for esotropia.

Grating acuity and stereopsis were measured longitudinally in five groups of infants: infantile esotropes, moderate hyperopes, high hyperopes, infants with a family history of strabismus or amblyopia and controls. Grating acuity was measured with a forced-choice preferential looking procedure. Stereopsis was assessed with a random-element stereogram. Testing was conducted when subjects were 3, 6, 9, 12, 18, 24, 30 and 36 months of age. No differences among groups in absolute acuity scores or interocular acuity differences were found until the infants reached 30 and 36 months of age. At these ages, treated infantile esotropes showed acuity scores that were, on average, 0.5 octave poorer than those of controls for both the eye showing the better acuity and the eye showing the worse acuity. Stereopsis testing indicated that few, if any, of the infantile esotropes showed stereopsis at any of the test ages. Over 30% of the high hyperopes developed strabismus by age 3 years, but none of the infants in the moderate hyperopia or family history groups developed strabismus.

Validation of the acuity card procedure for assessment of infants with ocular disorders.

The acuity card procedure has been shown to be a rapid method for the assessment of monocular and binocular grating acuity in normal infants from birth through 36 months of age. The current study seeks to validate the procedure further by using the acuity cards to assess 20 2- to 8-month-old infant patients with ocular disorders, including aphakia, strabismus, ptosis, and orbital hemangioma. Assessments were made with the acuity cards by two different observers, both blind to the infant's diagnosis, and by a third observer using a traditional forced-choice preferential looking (FPL) procedure. One hundred percent of the infant patients completed both binocular and monocular acuity card testing in an average time of 8 minutes per test. Interobserver agreement between acuity card observers and inter-technique agreement were high, and were sustained in individual cases in which the infant's acuity was not predictable from its visible signs. These results help to establish the potential clinical utility of the acuity card procedure for the assessment of infant patients.

Assessment of visual acuity in infants and children: the acuity card procedure.

The 'acuity card' procedure described here is a simplified method of testing visual acuity of infants and young children, and has been developed to allow preferential looking to be assessed in a laboratory or clinic. A higher proportion of children can be tested successfully than has been reported for more traditional procedures. Initial studies indicate that the acuity card procedure is a fast, accurate method for assessing the acuity of normal infants and children, and those with visual or neurological impairments, across a wide age-range and in both clinical and laboratory settings.

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.

Monocular acuity in normal infants: the acuity card procedure.

An "acuity card" technique has been developed for rapid assessment of visual acuity in infants. In this procedure an adult observer shows the infant a series of cards that contain gratings of various spatial frequencies and estimates acuity as the highest spatial frequency that the infant is judged to see. The present paper shows that the acuity card procedure can be used in a laboratory setting to estimate both monocular and binocular acuity in infants 1 to 12 months of age. Four monocular and two binocular acuity estimates were obtained on 36 normal infants, six each at ages 4, 8, and 16 weeks and 6, 9, and 12 months. Acuity estimate means and SD's agreed well with previously established preferential looking (PL) norms for each of the test ages. Time required for a monocular or a binocular test averaged 3 to 6 min.

Visual acuity screening of children 6 months to 3 years of age.

The operant preferential looking (OPL) procedure allows a behavioral estimate of visual acuity to be obtained from children 6 mo to 3 yr of age. In clinical settings, there is often too little time available to obtain an acuity estimate with the standard OPL procedure. The goal of this study was to identify specific spatial frequencies, termed diagnostic grating frequencies, that could enable the OPL technique to be used as a screening procedure under conditions where completion of acuity estimation was not possible. One hundred eighty presumptively normal children, 6, 12, 18, 24, 30, and 36 mo of age, were each tested with up to 20 trials of a potential diagnostic grating frequency to determine the highest spatial frequency grating that could be resolved by 90% of children at each age. For all ages except 18 mo, there existed a spatial frequency that produced uniformly high OPL performance within the age group; this spatial frequency was separated by one-half to one octave from a higher spatial frequency that more than 30% of children at that age failed to detect. These results suggest that at all ages except 18 mo, it should be possible to use the OPL procedure as a vision screening tool by testing individual children with the diagnostic grating frequency appropriate for their age.

The acuity card procedure: a rapid test of infant acuity.

Forced-choice preferential looking (FPL) and operant preferential looking (OPL) procedures for testing infant acuity typically require 15-45 min to derive an acuity estimate. This article presents a new acuity assessment technique ("acuity cards") that combines FPL/OPL stimuli with an observer's subjective assessment of an infant's looking behavior. The infant is shown a series of gray cards that contain grating targets of various spatial frequencies. An observer watches the eye movement patterns and behavior of the infant and judges whether the infant can or cannot see the grating on each card in the series. Acuity is estimated as the highest spatial frequency that the observer judges the infant to be able to see. With this technique, the binocular acuity of normal infants can be estimated with reasonable accuracy in the laboratory setting in 3-5 min.

Cycloplegic refractions of infants and young children: the axis of astigmatism.

Review of the cycloplegic refractions of all children who were first examined at Children's Hospital Medical Center in Boston between 1968 and 1978 revealed that 281 children between the ages of 0 and 9.5 years had astigmatism of 1 diopter (D) or greater but no other ophthalmological or neurological problems. In the 85 children under 3.5 years of age, against-the-rule astigmatism was 2.5 times more common than with-the-rule astigmatism, whereas in the 103 children over 5.5 years of age, with-the-rule astigmatism was three times as common as against-the-rule astigmatism. Eleven children who had been astigmatic as infants were recalled; follow-up refraction at ages 5-11 years revealed that all but three had at least a 0.75 D decrease in astigmatism. The remaining three had astigmatism equal in magnitude and axis to the astigmatism they had as infants. Thus, there is a high prevalence of against-the-rule astigmatism in infants and toddlers, which disappears by the time the children reach school age.

Assessment and prediction of visual acuity in 3- to 4-year-old children born prior to term.

Previous studies of school-age children born prior to term indicate that they often have visual acuity that is slightly poorer than normal. However, visual acuity results for preschool-age preterm children have not been reported. In this study, we used the operant preferential looking procedure to measure the visual acuities of 23 3- to 4-year-old preterm children. The results indicated that, although many of the children had acuities within the normal range, the average acuity of the preterm children was slightly poorer than that of full-term children of the same age, even when children with significant refractive errors were eliminated from the sample. Neither birthweight, gestational age at birth, nor the presence of respiratory distress syndrome during infancy were predictive of later visual acuity. However, preferential looking acuity screening at 4 months corrected age did have some predictive value, in that 3 of the 4 infants who failed to complete testing at 4 months showed poor performance at 3 to 4 years of age.