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.

The retina of the newborn human infant

We have examined a pair of eyes from a normal, full-term infant who died at 8 days as a result of accidental injury. Eyes were obtained immediately after death, fixed, and sectioned for light microscopy. Results from both eyes were substantially the same. The macular region was still drastically immature at 1 week. Even though a foveal depression existed, all cell layers were still present across it. Furthermore, the inner nuclear layer was divided into two separate layers. The receptor layer was reduced to one or two cells thick; receptors had both inner and outer segments, but they were very short and stumpy. The region of immaturity covered about 5 degrees of the retina. These findings suggest that the central region of a human infant's retina is probably not fully functional at birth.

Growth and development in term infants fed long-chain polyunsaturated fatty acids: a double-masked, randomized, parallel, prospective, multivariate study

OBJECTIVE

To evaluate the effects of dietary intake of the long-chain polyunsaturated fatty acids, arachidonic acid (AA), and docosahexaenoic acid (DHA) on multiple indices of infant growth and development.

DESIGN

A double-masked, randomized, parallel trial was conducted with term infants fed formulas with or without AA+DHA for 1 year (N = 239). Reference groups of breastfed infants (N = 165) weaned to formulas with and without AA+DHA were also studied. Infants in the formula groups were randomized at </=9 days of age to a control formula with no AA or DHA (n = 77) or 1 of 2 otherwise identical formulas containing AA+DHA (AA, 0.46% and DHA, 0.14% of total fatty acids) from either egg-derived triglyceride (egg-DTG [n=80]) or fish oil and fungal oil (fish/fungal [n = 82]) at levels similar to the average in breast milk samples as measured in the reference group. All formulas contained 50% of energy from fat with the essential dietary fatty acids, linoleic acid (20% fatty acids) and alpha-linolenic acid (2% fatty acids). The main study outcomes were AA and DHA levels in plasma and red blood cells, and multiple measures of infant development at multiple ages from birth to 14 months: growth, visual acuity, information processing, general development, language, and temperament.

RESULTS

AA and DHA levels in plasma and red cells were higher in AA+DHA-supplemented groups than in the control formula group and comparable to those in reference groups. No developmental test results distinguished these groups. Expected differences in family demographics associated with breastfeeding were found, but no advantages to breastfeeding on any of the developmental outcome demonstrated.

CONCLUSIONS

These findings do not support adding AA+DHA to formulas containing 10% energy as linoleic acid and 1% energy as alpha-linolenic acid to enhance growth, visual acuity, information processing, general development, language, or temperament in healthy, term infants during the first 14 months after birth.infant development, breast feeding, infant formula, long-chain polyunsaturated fatty acids, docosahexaenoic acid.

Prevalence of myopia between 3 months and 5 1/2 years in preterm infants with and without retinopathy of prematurity. Cryotherapy for Retinopathy of Prematurity Cooperative Group

PURPOSE

The purpose of the study was to examine spherical equivalent refractive errors, especially myopia, at six ages between 3 months and 5 1/2 years post-term in preterm children with birth weights of less than 1251 g.

DESIGN

A cohort study.

PARTICIPANTS

There were a total of 827 participants in the multicenter study of cryotherapy for retinopathy of prematurity (ROP). Approximately one third of the eyes did not develop ROP, whereas two thirds developed mild-to-severe ROP. None of the eyes underwent cryotherapy.

INTERVENTION

Refractive error was measured at 3 months, 1 year, and 5 1/2 years term due date at the five long-term follow-up centers. In most eyes, refractive error also was measured at 2, 3 1/2, and 4 1/2 years.

MAIN OUTCOME MEASURE

Myopia was defined as 0.25 diopter (D) or greater with high myopia as 5 D or greater.

RESULTS

The proportion of eyes with myopia in this preterm population was increased compared to published data on full-term children and was related to severity of both acute-phase and cicatricial-phase ROP. The percentage of eyes with myopia varied little across ages, ranging from 21.2% at 1 year to 15.7% at 4 1/2 years. The percentage of eyes with high myopia doubled from 1.8% to 3.9% between 3 months and 1 year and remained stable thereafter. The distribution of refractive errors in eyes with mild acute-phase ROP was similar to that of eyes with no ROP. In contrast, eyes with moderate or severe acute-phase ROP showed an increased prevalence of high myopia. The distribution of refractive errors changed between 3 months and 1 year with little change after 1 year. This pattern of refractive development differs from that of full-term infants. Birth weight, severity of ROP, and degree of myopia at 3 months predicted the presence of myopia and high myopia at 5 1/2 years of age.

CONCLUSIONS

The distribution of refractive errors in preterm infants from age 3 months to 5 1/2 years varies with severity of acute-phase ROP and cicatricial disease. Changes in refractive error distribution occur primarily between 3 months and 1 year and involve a decrease in the proportion of eyes with hyperopia and an increase in the proportion with high degrees of myopia.

Development of myopia in infants with birth weights less than 1251 grams. The Cryotherapy for Retinopathy of Prematurity Cooperative Group

The authors report on the incidence of myopia in a large group of premature infants with birth weights of less than 1251 g followed as part of the multicenter study of Cryotherapy for Retinopathy of Prematurity. None of the eyes reported here underwent cryotherapy. Eyes were refracted using cycloplegic retinoscopy at 3 months (n = 2916), 12 months (n = 2626), and 24 months (n = 961 at 5 of the 23 centers) after term. Myopia was observed in approximately 20% of the children at each test age. The percentage of high myopia (greater than or equal to 5 diopters) doubled from 2% to 4.6% between 3 and 12 months and remained stable thereafter. Lower birth weight and increasing severity of retinopathy of prematurity (ROP) were strong predictors of myopia and high myopia. In addition, anisometropia, astigmatism, and the presence of posterior pole residua from ROP also were associated with a higher incidence of myopia and high myopia.

Cycloplegic refractions in infants and young children

We studied groups of normal infants and infants with amblyopia and esoropia to determine the incidence of infantile astigmatism. Under cycloplegia, 19% of normal infants had astigmatism; this was at least twice the incidence in adults, but less than one-hale that found by noncycloplegic refractions of infants. During the first three postnatal years the incidence of astigmatism and distributions of spherical equivalents and anisometropia did not distinguish normal patients from most of those with esotropia and amblyopia.

Severity of neonatal retinopathy of prematurity is predictive of neurodevelopmental functional outcome at age 5.5 years. Behalf of the Cryotherapy for Retinopathy of Prematurity Cooperative Group

OBJECTIVE

The purpose of this study was to assess the relation between neonatal retinopathy of prematurity (ROP) in very low birth weight infants and neurodevelopmental function at age 5.5 years.

METHODS

Longitudinal follow-up of children occurred in 2 cohorts of the Multicenter Cryotherapy for Retinopathy of Prematurity Study. The extended natural history cohort followed 1199 survivors of <1251 g birth weight from 5 centers. The threshold randomized cohort (ThRz) followed 255 infants <1251 g from 23 centers who developed threshold ROP and who consented to cryotherapy to not more than 1 eye. At 5.5 years both cohorts had ophthalmic and acuity testing and neurodevelopmental functional status determined with the Functional Independence Measure for Children (WeeFIM).

RESULTS

Evaluations were completed on 88.7% of the extended natural history cohort; 87% had globally normal functional skills (WeeFIM: >95). As ROP severity increased, rates of severe disability increased from 3.7% among those with no ROP, to 19.7% of those with threshold ROP. Multiple logistic regression analysis demonstrated that better functional status was associated with favorable visual acuity, favorable 2-year neurological score, absence of threshold ROP, having private health insurance, and black race. Evaluations were completed on 87.4% of the ThRz children. In each functional domain, the 134 children with favorable acuity in their better eye had fewer disabilities than did the 82 children with unfavorable acuity: self-care disability 25.4% versus 76.8%, continency disability 4.5% versus 50.0%, motor disability 5.2% versus 42.7%, and communicative-social cognitive disability 22.4% versus 65.9%, respectively.

CONCLUSION

Severity of neonatal ROP seems to be a marker for functional disability at age 5. 5 years among very low birth weight survivors. High rates of functional limitations in multiple domains occur in children who had threshold ROP, particularly if they have unfavorable visual acuity.

Visual acuity of human infants at scotopic, mesopic and photopic luminances

Visual acuity of 2-month-old infants and adults was measured between -2.6 and +2.7 log10 cd/m2 using standard psychophysical techniques. The acuity-vs-luminance curve was similar for infants and adults: acuity improved with increasing luminance until 0.0 log cd/m2, and was constant above that luminance. However, the infant curve was slightly shallower than the adult curve, and infant acuity was over 3.5 octaves poorer than adult acuity at all luminances. The infant acuity-vs-luminance curve was compared with adult curves measured 21 degrees and 51 degrees from fixation, and at 21 degrees with +8, +/- 3.25 and 0.0 D of experimental refractive error. The results indicated that infants' poor acuity cannot be fully explained by: refractive error, foveal immaturity, scotopic detection of stimuli, functional similarity between infant vision and adult vision in the periphery, or by an overall reduction in visual sensitivity.

Visual and neurological outcome of infants with periventricular leukomalacia

Visual acuity, visual fields and neurological status were assessed in 10 infants with periventricular leukomalacia (PVL), tested at 16, 36, 48 and 72 weeks from the expected date of confinement. Monocular acuity development was normal in eight of the 10 infants, but was below normal in one infant at eight months and in another at 18 months. Over half the infants tested at 16, 36 and 48 weeks had smaller visual fields than those of 95 per cent of healthy preterm infants tested at the same ages, but by 72 weeks only two of six infants tested had restricted visual fields. Nine of the 10 infants were neurologically abnormal at ages under one year, but only four remained so beyond one year. These results indicate more favourable outcomes for visual acuity and neurological status in infants with non-cavitary PVL than have been reported in infants with cavitary PVL. The most compromised infants were one with cavitary PVL and another with extensive non-cavitary PVL who had the longest-lasting EEG abnormalities of all 10 infants.

Visual acuity in infants after vitrectomy for severe retinopathy of prematurity

During the course of the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP), 98 infants (129 eyes) from the randomized segment of the trial developed total retinal detachment from retinopathy of prematurity (ROP) before the 1-year examination. The authors report as a case series the results of acuity card assessment of monocular grating acuity at 1 year in 53 infants (71 eyes) postvitrectomy and in 45 infants (58 eyes) who had retinal detachments but who did not undergo retinal reattachment surgery. The decision to undertake and the surgical technique used for a retinal reattachment procedure was not part of the randomized CRYO-ROP trial. Two eyes of one infant had pattern vision at the lowest measurable threshold after vitrectomy. None of the remaining eyes that had undergone vitrectomy and none of the eyes that did not undergo vitrectomy showed evidence of pattern vision. The relatively poor visual outcomes in this case series suggest that efforts are well-spent in attempting to prevent retinal detachment in ROP.

Does cryotherapy affect refractive error? Results from treated versus control eyes in the cryotherapy for retinopathy of prematurity trial

PURPOSE

To evaluate the effect of cryotherapy on refractive error status between ages 3 months and 10 years in children with birth weights of less than 1251 g in whom severe retinopathy of prematurity (ROP) developed in one or both eyes during the neonatal period.

DESIGN

Randomized clinical trial.

PARTICIPANTS

Two hundred ninety-one children in whom severe ROP developed during the neonatal period.

INTERVENTION

Cryotherapy for ROP.

MAIN OUTCOME MEASURES

Cycloplegic Refraction

METHODS

The children underwent repeated follow-up eye examinations, including cycloplegic retinoscopy, between 3 months and 10 years after term due date. Refractive error data from all eyes that were randomized to cryotherapy were compared with data from all eyes that were randomized to serve as controls. Refractive error data were also compared for a subset of children who had both a treated and a control eye that could be refracted.

RESULTS

At all ages, the proportion of treated eyes that were unable to be refracted because of retinal detachment, media opacity, or pupillary miosis was approximately half the proportion of the control eyes that were unable to be refracted. When data from all eyes that could be refracted were considered, the distribution of refractive errors between fewer than 8 diopters (D) of myopia and more than 8 D of hyperopia was similar for treated and control eyes at all ages. The proportion of eyes with 8 D or more of myopia was much higher in treated than in control eyes at all ages after 3 months. In the subset of children who had a treated eye and a control eye that could be refracted, distributions of refractive errors in treated versus control eyes were similar at most ages.

CONCLUSIONS

In both treated and control eyes, there was an increase in the prevalence of high myopia between 3 and 12 months of age. Between 12 months and 10 years of age, there was little change in distribution of refractive error in treated or control eyes. The higher prevalence of myopia of 8 D or more in treated eyes, as compared with control eyes, may be the result of cryotherapy's preservation of retinal structure in eyes that, in the absence of cryotherapy, would have progressed to retinal detachment.

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.

Measurement of refractive error in Native American preschoolers: validity and reproducibility of autorefraction

PURPOSE

To examine (1) reproducibility of cycloplegic retinoscopy (C-RNS), cycloplegic autorefraction (C-Autoref), and noncycloplegic autorefraction (NC-Autoref), and (2) validity of C-Autoref and NC-Autoref compared with C-RNS in preschoolers with astigmatism.

METHODS

Subjects were 36 Native American preschoolers. Three measurements of right eye refractive error were obtained with each of three methods: C-RNS (by three different retinoscopists), C-Autoref, and NC-Autoref (Nikon Retinomax K+). Vector methods (vector dioptric distance, VDD) were used in the analyses.

RESULTS

Mean reproducibility was 0.41 D (SD = 0.18) for C-RNS, 0.25 D (SD = 0.17) for C-Autoref, and 0.37 D (SD = 0.21) for NC-Autoref. Mean agreement between C-Autoref and C-RNS ranged from 0.51 to 0.61 VDD (SD = 0.24 to 0.35), and ranged from 1.66 to 1.74 VDD (SD = 1.11 to 1.25) for agreement between NC-Autoref and C-RNS. Mean bias was -0.07 +0.21 x 149 and -1.33 +0.34 x 178 for C-Autoref and NC-Autoref, respectively.

CONCLUSIONS

C-Autoref provided reliable and valid measurements of refractive error in young children. NC-Autoref measurements were reliable within subjects, but there was large variability in validity among subjects.

Corneal and refractive astigmatism in a sample of 3- to 5-year-old children with a high prevalence of astigmatism

PURPOSE

To examine the relation between corneal and refractive astigmatism in a sample of pre-school-age Native American children with a high prevalence of astigmatism.

METHODS

Subjects were 250 Tohono O'Odham children, 3 to 5 years of age. Each child had corneal astigmatism measured with the Marco Nidek KM-500 portable autokeratometer without pupil dilation, and with the Nikon Retinomax K-Plus portable autorefractor/autokeratometer without and with pupil dilation. Refractive astigmatism was measured using the Retinomax K-Plus, with cycloplegia, confirmed by retinoscopy.

RESULTS

Corneal astigmatism exceeded refractive astigmatism, with a median vector dioptric difference of 0.88 D for the KM-500, 0.76 D for the Retinomax K-Plus without dilation, and 0.75 for the Retinomax K-Plus with dilation. The relation between corneal and refractive astigmatism was adequately described by the modification by Grosvenor et al. of Javal's rule, but not by laval's rule.

CONCLUSIONS

The results are in agreement with data reported previously for older Native American and non-Native American populations. The modified laval's rule adequately describes the relation between corneal and refractive astigmatism in a population; however, this rule does not provide accurate prediction of refractive astigmatism in individual children or adults.

Kinetic perimetry assessment of binocular visual field shape and size in young infants

Kinetic perimetry was used to measure the extent of the binocular visual field in 8 directions in 77 full-term infants tested as neonates, 4-week-olds, or 8-week-olds. The apparatus consisted of a black, 4-arm arc perimeter, a centrally-located 6-deg stationary white sphere, and an identical sphere that served as the peripheral target. Neonates showed larger visual fields than did 4- and 8-week-olds, perhaps due to the strength of the older infants' fixation of the central target. Infants at all ages showed significantly smaller fields than did adults. However, visual field shape was similar in infants and adults.

Reproducibility and accuracy of measurements with a hand held autorefractor in children

AIM

To determine reproducibility and accuracy of the Nikon Retinomax autorefractor when used with children who were made cycloplegic.

METHODS

Autorefraction and retinoscopy or subjectively refined retinoscopy (where, under the patient's direction, the refraction was varied until the best visual acuity was achieved) were performed on the right eye of 47 children, age 11-93 months. Autorefraction was performed using the Nikon Retinomax, which provides up to eight measured values of refractive error and one representative measurement of refractive error.

RESULTS

Autorefractor measurements were successfully obtained from 7/9 children age 3 years or younger, and from all older children. Vector methods were used to calculate differences. Retinomax reproducibility averaged 0.43 D. Unbiased Retinomax and retinoscopy measurements differed by an average of 0.82 D. Unbiased Retinomax and subjectively refined retinoscopy differed by an average of 1.03 D.

CONCLUSIONS

Reproducibility of Retinomax measured values in children is comparable with reproducibility of retinoscopy, subjective refraction, and autorefraction measurements in adults. Agreement between Retinomax and retinoscopy and agreement between Retinomax and subjective refinement in children is comparable with agreement between autorefraction and subjective refraction in adults. The study indicates that the Retinomax is a useful instrument for measuring refractive errors in young children.

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 of eyes after vitrectomy for retinopathy of prematurity: follow-up at 5 1/2 years. The Cryotherapy for Retinopathy of Prematurity Cooperative Group

PURPOSE

To provide long-term follow-up on the structural status and visual function at 5 1/2 years of age for 128 eyes of 98 infants who participated in the multicenter randomized clinical trial of cryotherapy for retinopathy of prematurity in whom total retinal detachment developed from retinopathy of prematurity (ROP) by the 3-month study examination. Fifty-four patients had lensectomy-vitrectomy procedures in one or both eyes before 1 year of age (n=72 eyes), and 44 patients did not (n=56 eyes).

METHODS

When the children were 5 1/2 years of age, an eye examination was performed and residua of ROP was assessed. Recognition acuity (Early Treatment of Diabetic Retinopathy Study chart) and grating visual acuity (Teller acuity card procedure) assessments were undertaken by testers who were masked to the status of each of the child's eyes.

RESULTS

At least partial retinal attachment was present at 5 1/2 years in 21% compared with 28% at 1 year of age (not significant). All except one of the eyes tested at 5 1/2 years had vision limited to light perception or no light perception, regardless of whether a vitrectomy had been performed. One eye that underwent vitrectomy had minimal pattern vision. The two eyes that were reported previously to have minimal pattern vision at 1 year of age were blind at the longer-term follow-up.

CONCLUSIONS

The poor visual outcome after a lensectomy-vitrectomy procedure for retinal detachment due to ROP demands that emphasis be placed on prevention of retinal detachment in premature infants.

Vision screening of preschool children: evaluating the past, looking toward the future

Vision problems of preschool children are detectable with a comprehensive eye examination; however, it is estimated that only 14% of children below the age of 6 years receive an eye examination. Screening is advocated as a cost-effective alternative to identify children in need of further vision care. Thirty-four states recommend or require vision screening of preschool children. Although laws and guidelines exist, only 21% of preschool children are actually screened for vision problems. There is little agreement concerning the best screening methods, and no validated, highly effective model for screening vision of preschool children. Newer screening tests have been designed specifically for preschool populations, and can be administered by lay screeners. Many have not been validated. Several are recommended by states or organizations without convincing scientific evidence of their effectiveness. This paper summarizes current laws and guidelines for preschool vision screening in the United States, reviews advantages and disadvantages of several test procedures, and provides recommendations for developing future preschool vision screening programs.