Progression of myopia and high myopia in the Early Treatment for Retinopathy of Prematurity study: findings at 4 to 6 years of age.

PURPOSE: To report the prevalence of myopia and high myopia in children <6 years of age born preterm with birth weights <1251 g who developed high-risk prethreshold retinopathy of prematurity and who participated in the Early Treatment for Retinopathy of Prematurity trial. METHODS: Surviving children from the cohort of 401 participants who had developed high-risk prethreshold ROP in one or both eyes underwent cycloplegic retinoscopy at 6 and 9 months corrected age and yearly between 2 and 6 years postnatal age. Eyes were randomized to receive treatment at high-risk prethreshold ROP or conventional management with treatment only if threshold ROP developed. Myopia (spherical equivalent ≥0.25 D) or high myopia (≥5.00 D) in eyes at 4-, 5-, and 6-year examinations was reported. RESULTS: At ages 4, 5, and 6 years, there was no difference in the percentage of eyes with myopia (range, 64.8%-69.9%) and eyes with high myopia (range, 35.3%-39.4%) between earlier treated and conventionally managed eyes. CONCLUSIONS: Approximately two-thirds of eyes with high-risk prethreshold ROP during the neonatal period are likely to be myopic into the preschool and early school years. In addition, the increase in the proportion of eyes with high myopia that had been observed in both earlier-treated and conventionally managed eyes between ages 6 months and 3 years does not continue between ages 3 and 6 years.

Developmental changes in anterior corneal astigmatism in Tohono O'odham Native American infants and children.

UNLABELLED: ABSTRACT Purpose: To describe change in corneal astigmatism in infants and children of a Native American tribe with a high prevalence of astigmatism. METHODS: Longitudinal measurements of corneal astigmatism were obtained in 960 Tohono O'odham children aged 6 months to <8 years. Change in corneal astigmatism (magnitude (clinical notation), J0, J45) across age in children with high astigmatism (≥2 diopter (D) corneal astigmatism) or low/no astigmatism (<2 D corneal astigmatism) at their baseline measurement was assessed. RESULTS: Regression analyses indicated that early in development (6 months to <3 years), astigmatism magnitude decreased in the high astigmatism group (0.37 D/year) and remained stable in the low/no astigmatism group. In later development (3 to <8 years), astigmatism decreased in the high (0.11 D/year) and low/no astigmatism groups (0.03 D/year). In 52 children who had data at all three of the youngest ages (6 months to <1 year, 1 to <2 years, 2 to <3 years) astigmatism decreased after infancy in those with high astigmatism (p = 0.021), and then remained stable from age 1-2 years, whereas astigmatism was stable from infancy through age 1 year and increased from age 1-2 years in the low/no astigmatism group (p = 0.026). J0 results were similar, but results on J45 yielded no significant effects. CONCLUSIONS: The greatest change occurred in highly astigmatic infants and toddlers (0.37 D/year). By age 3 years, change was minimal and not clinically significant. Changes observed were due primarily to change in the J0 component of astigmatism.

Accuracy and validity of IK4 handheld video keratometer measurements in children.

The infant keratometer (IK4) is a custom handheld instrument that was designed specifically to allow measurement of corneal astigmatism in infants as young as 6 months of age. In this study, accuracy of IK4 measurements with the use of standard toric surfaces was within 0.25 D. Validity measurements obtained in 860 children aged 3-7 years demonstrated slightly greater astigmatism measurements in the IK4 than in the Retinomax K+. Measurement success was 98% when the IK4 was used. The IK4 may prove to be clinically useful for screening children as young as 3 years of age at high risk for corneal astigmatism.

Astigmatism progression in the early treatment for retinopathy of prematurity study to 6 years of age.

PURPOSE: To examine the prevalence of astigmatism (≥ 1.00 diopter [D]) and high astigmatism (≥ 2.00 D) from 6 months after term due date to 6 years of age in preterm children with birth weight of less than 1251 g in whom high-risk prethreshold retinopathy of prematurity (ROP) developed and who participated in the Early Treatment for ROP study. DESIGN: Observational cohort study. PARTICIPANTS: Four hundred one infants in whom high-risk prethreshold ROP developed in 1 or both eyes and were randomized to early treatment (ET) versus conventional management (CM). Refractive error was measured by cycloplegic retinoscopy. Eyes were excluded if they underwent additional retinal, glaucoma, or cataract surgery. INTERVENTION: Eyes were randomized to receive laser photocoagulation at high-risk prethreshold ROP or to receive treatment only if threshold ROP developed. MAIN OUTCOME MEASURES: Astigmatism and high astigmatism at each study visit. RESULTS: For both ET and CM eyes, there was a consistent increase in prevalence of astigmatism over time, increasing from 42% at 4 years to 52% by 6 years for the group of ET eyes and from 47% to 54%, respectively, in the CM eyes. There was no statistically significant difference between the slopes (rate of change per month) of the ET and CM eyes for both astigmatism and high astigmatism (P = 0.75). CONCLUSIONS: By 6 years of age, astigmatism of 1.00 D or more developed in more than 50% of eyes with high-risk prethreshold ROP, and nearly 25% of such eyes had high astigmatism (≥ 2.00 D). Presence of astigmatism was not influenced by timing of treatment, zone of acute-phase ROP, or presence of plus disease. However, there was a trend toward higher prevalence of astigmatism and high astigmatism in eyes with ROP residua. Most astigmatism was with-the-rule (75°-105°). More eyes with type 2 than type 1 ROP had astigmatism by 6 years. These findings reinforce the need for follow-up eye examinations through early grade school years in infants with high-risk prethreshold ROP. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Grating visual acuity results in the early treatment for retinopathy of prematurity study.

OBJECTIVE: To compare grating (resolution) visual acuity at 6 years of age in eyes that received early treatment (ET) for high-risk prethreshold retinopathy of prematurity (ROP) with that in eyes that underwent conventional management (CM). METHODS: In a randomized clinical trial, infants with bilateral, high-risk prethreshold ROP (n = 317) had one eye undergo ET and the other eye undergo CM, with treatment only if ROP progressed to threshold severity. For asymmetric cases (n = 84), the high-risk prethreshold eye was randomized to ET or CM. MAIN OUTCOME MEASURE: Grating visual acuity measured at 6 years of age by masked testers using Teller acuity cards. RESULTS: Monocular grating acuity results were obtained from 317 of 370 surviving children (85.6%). Analysis of grating acuity results for all study participants with high-risk prethreshold ROP showed no statistically significant overall benefit of ET (18.1% vs 22.8% unfavorable outcomes; P = .08). When the 6-year grating acuity results were analyzed according to a clinical algorithm (high-risk types 1 and 2 prethreshold ROP), a benefit was seen in type 1 eyes (16.4% vs 25.2%; P = .004) undergoing ET, but not in type 2 eyes (21.3% vs 15.9%; P = .29). CONCLUSION: Early treatment of eyes with type 1 ROP improves grating acuity outcomes, but ET for eyes with type 2 ROP does not. APPLICATION TO CLINICAL MEDICINE: Type 1 eyes should be treated early; however, based on acuity results at 6 years of age, type 2 eyes should be cautiously monitored for progression to type 1 ROP. Trial Registration clinicaltrials.gov Identifier: NCT00027222.

Prevalence of corneal astigmatism in Tohono O'odham Native American children 6 months to 8 years of age.

PURPOSE: To describe the prevalence of corneal astigmatism in infants and young children who are members of a Native American tribe with a high prevalence of refractive astigmatism. METHODS: The prevalence of corneal astigmatism was assessed by obtaining infant keratometer (IK4) measurements from 1235 Tohono O'odham children, aged 6 months to 8 years. RESULTS: The prevalence of corneal astigmatism >2.00 D was lower in the 1- to <2-year-old age group when compared with all other age groups, except the 6- to <7-year-old group. The magnitude of mean corneal astigmatism was significantly lower in the 1- to <2-year age group than in the 5- to <6-, 6- to <7-, and 7- to <8-year age groups. Corneal astigmatism was with-the-rule (WTR) in 91.4% of astigmatic children (≥1.00 D). CONCLUSIONS: The prevalence and mean amount of corneal astigmatism were higher than reported in non-Native American populations. Mean astigmatism increased from 1.43 D in 1-year-olds to nearly 2.00 D by school age.

Adult discrimination performance for pediatric acuity test optotypes.

PURPOSE: To compare adult discrimination performance on nine pediatric visual acuity tests to determine the consistency of optotype design. METHODS: After their binocular acuity was measured with each test, eight adult observers (mean age, 27 years ± 6.3 SD; three emmetropes and five corrected myopes) were shown isolated single optotypes from the Allen figures, HOTV, Landolt C, Lea Numbers, Lea Symbols, Lighthouse, Patti Pics, Precision Vision numbers, and Tumbling E tests. A one-interval, two-alternative forced-choice protocol was used at a single distance, and each optotype was paired with all optotypes from the same chart. Confusion matrices were generated for each test and Luce's (1963) biased-choice model was fit to each matrix to derive measures of pairwise similarity between the optotypes. RESULTS: The acuities from the Allen figures (P < 0.001) and HOTV (P = 0.029) were the only ones to differ significantly from the reference Landolt C. The choice-model analyses of the confusion matrices revealed that the Allen figures, HOTV, Lighthouse, Patti Pics, and Precision Vision numbers tests all had significant differences in discriminability of optotypes within the test. CONCLUSIONS: Pediatric acuity test optotypes are not all equally discriminable to adult observers with normal vision and no ocular disorders. The current data suggest that care must be taken when presenting limited numbers of optotypes, as is done with young patients.

Visual field extent at 6 years of age in children who had high-risk prethreshold retinopathy of prematurity.

OBJECTIVE: To compare monocular visual field extent at 6 years of age in eyes with high-risk prethreshold retinopathy of prematurity (ROP) randomized to early treatment (ET) with eyes that underwent conventional management (CM) and were treated at threshold or regressed without treatment. METHODS: Subjects were 370 surviving study participants who developed high-risk prethreshold ROP and were enrolled in the Early Treatment for Retinopathy of Prematurity Study between October 1, 2000, and September 30, 2002. When the participants were 6 years of age, vision testers unaware of ROP status used white-sphere kinetic perimetry to measure visual field extent along the superotemporal, inferotemporal, inferonasal, and superonasal meridians. RESULTS: The extent of the visual field was 0.1° to 3.7° larger in ET eyes when blind eyes were assigned a score of 0°. When data were examined from eyes of participants with 1 sighted ET eye and 1 sighted CM eye, ET eyes showed a small (1.3°-3.1°) reduction, which was statistically significant only along the superonasal meridian (P = .005). In bilaterally sighted children, visual field extent was not significantly reduced for high-risk type 1 ET eyes (-0.9° to 1.8°). However, in ET eyes with high-risk type 2 disease, visual field extent was significantly smaller compared with that of CM eyes (3.6°-8.7° superonasal field [P = .003]; inferonasal field [P < .001]). CONCLUSION: Early treatment preserves peripheral vision, with only a small reduction of visual field extent. APPLICATION TO CLINICAL PRACTICE: Early treatment for high-risk prethreshold ROP does not adversely affect visual field extent clinically.

Retinopathy of prematurity in infants weighing less than 500 grams at birth enrolled in the early treatment for retinopathy of prematurity study.

PURPOSE: To describe patient characteristics, classification, and onset of prethreshold retinopathy of prematurity (ROP), and ocular findings at 6 months corrected age in infants with birth weights <500 g who were enrolled in the Early Treatment for Retinopathy of Prematurity (ETROP) Study. DESIGN: Multicenter randomized clinical trial. PARTICIPANTS: Sixty-three infants with birth weights <500 g who developed ROP and were enrolled in the ETROP Study. METHODS: Infants <1251 g at birth were logged at 26 study centers from October 1, 2000, to September 30, 2002, and underwent examinations for ROP. Infants who developed ROP and whose parents/legal guardians consented were enrolled in the ETROP Study. Infants who developed high-risk prethreshold ROP were randomized; 1 eye was treated early with peripheral retinal ablation and the other eye was managed conventionally, or, in asymmetric cases, the high-risk eye was randomized to early peripheral retinal ablation or conventional management. All eyes reaching prethreshold ROP were examined when infants reached 6 months corrected age. MAIN OUTCOME MEASURES: Retinopathy of prematurity incidence, characteristics, and ocular findings among participants. RESULTS: Thirty-four infants reached prethreshold or worse severity in 1 or both eyes. Retinopathy of prematurity was located in zone I in 43.3% of all prethreshold eyes, and plus disease was present in 46.7%. Median postmenstrual age for diagnosis of all prethreshold ROP was 36.1 weeks, but earlier (35.1 weeks) for eyes that developed high-risk prethreshold ROP. In the 27 surviving infants with prethreshold ROP, ophthalmic examination at 6 months corrected age showed a normal posterior pole in 22 (81.5%), a favorable structural outcome with posterior pole abnormalities in 4 (14.8%), and an unfavorable structural outcome (stage 4B) in 1 (3.7%). One infant developed amblyopia, 4 infants developed nystagmus, 4 infants developed strabismus, and 8 infants developed myopia >-5.00 diopters. CONCLUSIONS: This is the first report on characteristics of prethreshold ROP in infants with birth weights <500 g. These infants are at high risk for developing prethreshold ROP, although many initially achieve a favorable structural outcome. They are at risk of developing strabismus, nystagmus, high myopia, and abnormal retinal structure and should therefore receive continued long-term follow-up. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Final visual acuity results in the early treatment for retinopathy of prematurity study.

OBJECTIVE: To compare visual acuity at 6 years of age in eyes that received early treatment for high-risk prethreshold retinopathy of prematurity (ROP) with conventionally managed eyes. METHODS: Infants with symmetrical, high-risk prethreshold ROP (n = 317) had one eye randomized to earlier treatment at high-risk prethreshold disease and the other eye managed conventionally, treated if ROP progressed to threshold severity. For asymmetric cases (n = 84), the high-risk prethreshold eye was randomized to either early treatment or conventional management. The main outcome measure was ETDRS visual acuity measured at 6 years of age by masked testers. Retinal structure was assessed as a secondary outcome. RESULTS: Analysis of all subjects with high-risk prethreshold ROP showed no statistically significant benefit for early treatment (24.3% vs 28.6% [corrected] unfavorable outcome; P = .15). Analysis of 6-year visual acuity results according to the Type 1 and 2 clinical algorithm showed a benefit for Type 1 eyes (25.1% vs 32.8%; P = .02) treated early but not Type 2 eyes (23.6% vs 19.4%; P = .37). Early-treated eyes showed a significantly better structural outcome compared with conventionally managed eyes (8.9% vs 15.2% unfavorable outcome; P < .001), with no greater risk of ocular complications. CONCLUSIONS: Early treatment for Type 1 high-risk prethreshold eyes improved visual acuity outcomes at 6 years of age. Early treatment for Type 2 high-risk prethreshold eyes did not. Application to Clinical Practice Type 1 eyes, not Type 2 eyes, should be treated early. These results are particularly important considering that 52% of Type 2 high-risk prethreshold eyes underwent regression of ROP without requiring treatment. Trial Registration clinicaltrials.gov Identifier: NCT00027222.

Progression of type 2 to type 1 retinopathy of prematurity in the Early Treatment for Retinopathy of Prematurity Study.

OBJECTIVE: To examine the frequency and timing of progression from type 2 to type 1 retinopathy of prematurity (ROP) in the Early Treatment for Retinopathy of Prematurity Study. METHODS: Infants with prethreshold ROP that was no worse than low risk in 1 or both eyes, based on the RM-ROP2 model, were examined every 2 to 4 days for at least 2 weeks. Using the Early Treatment for Retinopathy of Prematurity Study-defined classification of eyes as having type 1 or type 2 prethreshold ROP, we analyzed the time to conversion from type 2 to type 1. Data were analyzed for 1 randomly selected eye for each child. RESULTS: Of 294 eyes at first diagnosis of type 2 ROP, 65 (22.1%) progressed to type 1 (mean [SD] interval, 9.0 [6.6] days; median, 7.0 days). Of 217 eyes with type 2 ROP that had an examination in less than 7 days, 25 (11.5%) were diagnosed with type 1 ROP in less than 7 days. Of 200 eyes that continued to have type 2 disease at the first follow-up examination and underwent a subsequent examination, 24 (15.7% of the 153 eyes that had an examination in <7 days) developed type 1 ROP in less than 7 days. The risk of progression from type 2 to type 1 in less than 7 days was greatest between 33 and 36 weeks' postmenstrual age, regardless of zone of retinopathy. CONCLUSIONS: Type 1 ROP can be identified with weekly examinations in most eyes with initial diagnosis of type 2 ROP; a small subset progresses to type 1 in less than 7 days. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00027222.

Prevalence of astigmatism in Native American infants and children.

PURPOSE: To describe the prevalence of high astigmatism in infants and young children who are members of a Native American tribe with a high prevalence of astigmatism. METHODS: SureSight autorefraction measurements were obtained for 1461 Tohono O'odham children aged 6 months to 8 years. RESULTS: The prevalence of astigmatism >2.00 diopters was 30% in Tohono O'odham children during infancy (6 months to <1 year of age) and was 23 to 29% at ages 2 to 7 years. However, prevalence dipped to 14% in children 1 to <2 years of age. At all ages, axis of astigmatism was with-the-rule (plus cylinder axis 90 degrees +/- 30 degrees ) in at least 94% of cases. CONCLUSIONS: As in non-Native American populations, Tohono O'odham infants show a high prevalence of astigmatism, which decreases in the second year of life. However, the prevalence of high astigmatism in Tohono O'odham children increases by age 2 to <3 years to a level near that seen in infancy and remains at that level until at least age 8 years. Longitudinal data are needed to determine whether the increase in high astigmatism after infancy occurs in infants who had astigmatism as infants or is due to the development of high astigmatism in children who did not show astigmatism during infancy.

Amblyopia in astigmatic infants and toddlers.

PURPOSE: To determine whether reduced astigmatism-corrected acuity for vertical (V) and/or horizontal (H) gratings and/or meridional amblyopia (MA) are present before 3 years of age in children who have with-the-rule astigmatism. METHODS: Subjects were 448 children, 6 months through 2 years of age with no known ocular abnormalities other than with-the-rule astigmatism, who were recruited through Women, Infants and Children clinics on the Tohono O'odham reservation. Children were classified as non-astigmats (< or =2.00 diopters) or astigmats (>2.00 diopters) based on right eye non-cycloplegic autorefraction measurements (Welch Allyn SureSight). Right eye astigmatism-corrected grating acuity for V and H stimuli was measured using the Teller Acuity Card procedure while children wore cross-cylinder lenses to correct their astigmatism or plano lenses if they had no astigmatism. RESULTS: Astigmatism-corrected acuity for both V and H gratings was significantly poorer in the astigmats than in the non-astigmats, and the reduction in acuity for astigmats was present for children in all three age groups examined (6 months to <1 year, 1 to <2 years, and 2 to <3 years). There was no significant difference in V-H grating acuity (no evidence of MA) for the astigmatic group as a whole, or when data were analyzed for each age group. CONCLUSIONS: Even in the youngest age group, astigmats tested with astigmatism correction showed reduced acuity for both V and H gratings, which suggests that astigmatism is having a negative influence on visual development. We found no evidence of orientation-related differences in astigmatism-corrected grating acuity, indicating either that MA does not develop before 3 years of age, or that most of the astigmatic children had a type of astigmatism, i.e., hyperopic, that has proven to be less likely than myopic or mixed astigmatism to result in MA.

Prevalence of strabismus among preschool, kindergarten, and first-grade Tohono O'odham children.

BACKGROUND: Although the prevalence of strabismus is 2% to 5% in European-based and African-American populations, little is known about the prevalence of strabismus in Native-American populations. We report the prevalence of strabismus in children who are members of a Native-American tribe with a high prevalence of astigmatism. METHODS: Subjects were 594 children enrolled in Head Start and 315 children enrolled in kindergarten or first grade (K/1) in schools on the Tohono O'odham Reservation. Distance and near cover tests were performed on each child by an ophthalmologist or optometrist, and cycloplegic refraction was obtained. RESULTS: Strabismus was detected in 9 Head Start children (1.5%) and 3 K/1 children (1.0%). Ratio of esotropia to exotropia was 1:3 in Head Start and 1:2 in K/1. Anisometropia >or=1.00 diopter (D) spherical equivalent was present in 2 children with strabismus, and anisometropia >or=1.00 D cylinder was present in 4 with strabismus. CONCLUSION: The prevalence of strabismus in Tohono O'odham children is at the low end of the prevalence range reported in studies of European-based and African-American populations.

Recognition acuity, grating acuity, contrast sensitivity, and visual fields in 6-year-old children.

OBJECTIVE: To measure monocular distance visual acuity (VA), grating VA, contrast sensitivity, and visual field extent in full-term, 6-year-old children. METHODS: Subjects were 59 healthy full-term children aged 5.8 to 6.3 years who had no ocular abnormalities and no myopia of 1.00 diopter (D) or greater, hyperopia of 4.00 D or greater, astigmatism of 1.50 D or greater, or anisometropia of 1.50 D or greater spherical equivalent or cylinder, as evaluated by a standard eye examination with cycloplegic refraction. All were tested monocularly for recognition acuity (Early Treatment Diabetic Retinopathy Study VA charts), grating acuity (Teller acuity cards), contrast sensitivity (Pelli-Robson contrast sensitivity charts), and visual field extent (white-sphere kinetic perimetry). RESULTS: Right and left eye values did not differ significantly. Mean values for the right eye were 0.040 logMAR (SD, 0.075 log units) for Early Treatment Diabetic Retinopathy Study VA, 24.5 cycles per degree (SD, 0.3 octaves) for grating acuity, and 1.63 (SD, 0.12 log units) for contrast sensitivity. Mean visual field extent for the inferonasal, superonasal, superotemporal, and inferotemporal meridians was 59.1 degrees (SD, 9.7 degrees), 57.8 degrees (SD, 9.6 degrees), 71.2 degrees (SD, 12.3 degrees), and 100.4 degrees (SD, 6.6 degrees), respectively. CONCLUSIONS: The results provide additional normative monocular data on visual function in 6-year-old children and indicate that their thresholds are less than those of adults for distance recognition VA, grating VA, and contrast sensitivity, but similar to those of adults for white-sphere kinetic perimetry.

Accuracy of the Welch Allyn SureSight for measurement of magnitude of astigmatism in 3- to 7-year-old children.

PURPOSE: To evaluate the accuracy of the Welch Allyn SureSight in noncycloplegic measurements of astigmatism as compared to cycloplegic Retinomax K+ autorefractor measurements of astigmatism in children from a Native American population with a high prevalence of high astigmatism. METHODS: Data are reported for 825 3- to 7-year-old children with no ocular abnormalities. Each child had a Retinomax K+ cycloplegic measurement of right eye astigmatism with a confidence rating > or =8 and 3 attempts to obtain a SureSight measurement on the right eye. RESULTS: SureSight measurement success rates did not differ significantly across age or measurement confidence rating (<6 vs > or =6). Ninety-six percent of children had at least 1 measurement (any confidence), and 89% had at least 1 measurement with confidence at the manufacturer's recommended value (> or =6). Overall, the SureSight tended to overestimate astigmatism. If the SureSight measurement had any dioptric value (0.00 D to 3.00 D), astigmatism of 2.00 D or less was likely to be present. If the SureSight showed astigmatism beyond the instrument's dioptric range (>3.00 D), Retinomax K+ measurements indicated that >2.00 D of astigmatism was present in 136 of 157 (86.6%). In cooperative children for whom the SureSight would not give a reading, 32 of 34 (94%) had >3.00 D of astigmatism. CONCLUSIONS: The SureSight does not provide an accurate, quantitative measure of amount of astigmatism. However, it does allow accurate categorization of amount of astigmatism as < or =2.00 D, >2.00 D, or >3.00 D, and it has high measurement success rate in young children.

Normative monocular visual acuity for early treatment diabetic retinopathy study charts in emmetropic children 5 to 12 years of age.

OBJECTIVE: To provide normative data for children tested with Early Treatment Diabetic Retinopathy Study (ETDRS) charts. DESIGN: Cross-sectional study. PARTICIPANTS: A total of 252 Native American (Tohono O'odham) children aged 5 to 12 years. On the basis of cycloplegic refraction conducted on the day of testing, all were emmetropic (myopia < or =0.25 diopter [D] spherical equivalent, hyperopia < or =1.00 D spherical equivalent, and astigmatism < or =0.50 D in both eyes). METHODS: Monocular visual acuity was tested at 4 m, using 1 ETDRS chart for the right eye (RE) and another for the left eye (LE). MAIN OUTCOME MEASURES: Visual acuity was scored as the total number of letters correctly identified, by naming or matching to letters on a lap card, and as the smallest letter size for which the child identified 3 of 5 letters correctly. RESULTS: Visual acuity results did not differ for the RE versus the LE, so data are reported for the RE only. Mean visual acuity for 5-year-olds (0.16 logarithm of the minimum angle of resolution [logMAR] [20/29]) was significantly worse than for 8-, 9-, 10-, 11-, and 12-year-olds (0.05 logMAR [20/22] or better at each age). The lower 95% prediction limit for determining whether a child has visual acuity within the normal range was 0.38 (20/48) for 5-year-olds and 0.30 (20/40) for 6- to 12-year-olds, which was reduced to 0.32 (20/42) for 5-year-olds and 0.21 (20/32) for 6- to 12-year-olds when recalculated with outlying data points removed. Mean interocular acuity difference did not vary by age, averaging less than 1 logMAR line at each age, with a lower 95% prediction limit of 0.17 log unit (1.7 logMAR lines) across all ages. CONCLUSIONS: For monocular visual acuity based on ETDRS charts to be in the normal range, it must be better than 20/50 for 5-year-olds and better than 20/40 for 6- to 12-year-olds. Normal interocular acuity difference includes values of less than 2 logMAR lines. Normative ETDRS visual acuity values are not as good as norms reported for adults, suggesting that a child's visual acuity results should be compared with norms based on data from children, not with adult norms.

A comparison of Lea Symbol vs ETDRS letter distance visual acuity in a population of young children with a high prevalence of astigmatism.

PURPOSE: To compare visual acuity results obtained by use of the Lea Symbols chart with results obtained with Early Treatment Diabetic Retinopathy Study (ETDRS) charts in young children who are members of a population with a high prevalence of astigmatism. METHODS: Subjects were 438 children ages 5 through 7 years who were enrolled in kindergarten or first grade on the Tohono O'odham Reservation: 241 (55%) had astigmatism >or=1.00 D in one or both eyes (range, 0.00-6.75 D). While wearing best correction, each child had right eye visual acuity tested with the 62 cm by 65 cm Lea Symbols chart at 3 m and with the 62 cm by 65 cm ETDRS chart at 4 m. Visual acuity was scored as the smallest optotype size at which the child correctly identified 3 of a maximum of 5 optotypes. ETDRS visual acuity also was scored based on the total number of letters that the child correctly identified. RESULTS: Correlation between Lea Symbols visual acuity and ETDRS visual acuity was 0.78 (p < 0.001). Mean Lea Symbols visual acuity was one-half line (0.04-0.06 logMAR) better than mean ETDRS visual acuity (p < 0.001). The difference between Lea Symbols and ETDRS visual acuity was not correlated with the mean of the Lea Symbols and ETDRS visual acuity scores, which ranged from -0.3 logMAR (20/10) to 0.74 logMAR (20/110). CONCLUSIONS: In this population of young children, in whom the primary source of reduced visual acuity is astigmatism-related amblyopia, the Lea Symbols chart produced visual acuity scores that were about 0.5 line better than visual acuity scores obtained with ETDRS charts.