Ruth E. Manny

Ocular component data in schoolchildren as a function of age and gender.

Purpose. To describe the refractive error and ocular components of a large group of school-aged children as a function of age and gender. Methods. In this report, we describe the refractive error and ocular components of 2583 school-aged children (49.3% girls, overall mean [±SD] age 10.0 ± 2.3). Measurement methods included cycloplegic autorefraction, autokeratometry, videophakometry, and A-scan ultrasonography. For statistical comparisons across gender and age, a critical point of &agr; = 0.005 was used to assess significance because of the large sample size and the large number of comparisons made. Results. Of these 2583 children, 10.1% were myopic (−0.75 D or more myopia in both meridians), and 8.6% were hyperopic (+1.25 D or more hyperopia in both meridians). As would be expected, there was a significant effect of age on refractive error (spherical equivalent, p < 0.0001), toward less hyperopia/more myopia. There was no significant difference in the average refractive error between girls and boys (p = 0.0192). Girls had steeper corneas than boys (0.74 D steeper in the vertical meridian and 0.63 D steeper in the horizontal meridian, p < 0.0001). There were no significant differences in corneal power with age (p = 0.16). Both older age and male gender were significantly associated with deeper anterior chambers (p < 0.0001 for both). The crystalline lens showed significant thinning with age (p < 0.0001), however, there was no significant difference in the lens thickness between girls and boys (p = 0.66). Both Gullstrand lens power and calculated lens power showed significant effects of age and gender (p < 0.0001 for both). Girls, on average, had Gullstrand lens powers that were 0.28 D steeper and calculated lens powers that were 0.80 D more powerful than boys. Axial length also showed significant effects of age and gender (p < 0.0001 for both). Girls’ eyes were, on average, 0.32 mm shorter than those of boys. Conclusions. These cross-sectional data show a general pattern of ocular growth, no change in corneal power, and crystalline lens thinning and flattening between the ages of 6 and 14 years. Girls tended to have steeper corneas, stronger crystalline lenses, and shorter eyes compared with boys.

Relative Peripheral Refractive Error and the Risk of Onset and Progression of Myopia in Children

PURPOSE To investigate whether relative peripheral hyperopia is a risk factor for either the onset of myopia in children or the rate of myopic progression. METHODS The risk of myopia onset was assessed in 2043 nonmyopic third-grade children (mean age ± SD = 8.8 ± 0.52 years) participating in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study between 1995 and 2007, 324 of whom became myopic by the eighth grade. Progression analyses used data from 774 myopic children in grades 1 to 8. Foveal and relative peripheral refractive error 30° in the nasal visual field was measured annually by using cycloplegic autorefraction. Axial length was measured by A-scan ultrasonography. RESULTS The association between more hyperopic relative peripheral refractive error in the third grade and the risk of the onset of myopia by the eighth grade varied by ethnic group (Asian children odds ratio [OR] = 1.56, 95% confidence interval [CI] = 1.06-2.30; African-American children OR = 0.75, 95% CI = 0.58-0.96; Hispanics, Native Americans, and whites showed no significant association). Myopia progression was greater per diopter of more hyperopic relative peripheral refractive error, but only by a small amount (-0.024 D per year; P = 0.02). Axial elongation was unrelated to the average relative peripheral refractive error (P = 0.77), regardless of ethnicity. CONCLUSIONS Relative peripheral hyperopia appears to exert little consistent influence on the risk of the onset of myopic refractive error, on the rate of myopia progression, or on axial elongation.

Time outdoors, visual activity, and myopia progression in juvenile-onset myopes.

PURPOSE To investigate the association between myopia progression and time spent outdoors and in various visual activities. METHODS Subjects were 835 myopes (both principal meridians -0.75 diopters [D] or more myopia by cycloplegic autorefraction) in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study with both progression data and at least one measure of activity associated with a progression interval. Activity data were collected by parental survey. Average activity level (mean of the activity at the beginning and the end of a 1-year progression interval) was the primary predictor in a repeated-measures mixed model. The model controlled for age, sex, ethnicity, refractive error at the beginning of the progression interval, clinic site, and type of autorefractor used. Effects were scaled based on performing an additional 10 hours per week of an activity. RESULTS In the multivariate model, the number of hours of reading for pleasure per week was not significantly associated with annual myopia progression at an a priori level of P ≤ 0.01, nor were the other near activities, the near-work composite variable diopter-hours, or outdoor/sports activity. The magnitude of effects was clinically small. For example, the largest multivariate effect was that each additional 10 hours of reading for pleasure per week at the end of a progression interval was associated with an increase in average annual progression by -0.08 D. CONCLUSIONS Despite protective associations previously reported for time outdoors reducing the risk of myopia onset, outdoor/sports activity was not associated with less myopia progression following onset. Near work also had little meaningful effect on the rate of myopia progression.

Visual Activity before and after the Onset of Juvenile Myopia

PURPOSE To investigate visual activities before and after the onset of juvenile myopia. METHODS The subjects were 731 incident myopes (-0.75 D or more myopia on cycloplegic autorefraction in both meridians) and 587 emmetropes (between -0.25 and +1.00 D) in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study. Parents supplied visual activity data annually. Data from myopic children 5 years before through 5 years after myopia onset were compared to data from age-, sex-, and ethnicity-matched models of children who remained emmetropic. RESULTS Hours per week spent reading or using a computer/playing video games did not differ between the groups before myopia onset; however, hours per week for both activities were significantly greater in myopes than in emmetropes at onset and in 4 of the 5 years after onset by 0.7 to 1.6 hours per week. Hours per week spent in outdoor/sports activities were significantly fewer for children who became myopic 3 years before onset through 4 years after onset by 1.1 to 1.8 hours per week. Studying and TV watching were not significantly different before myopia onset. CONCLUSIONS Before myopia onset, near work activities of future myopic children did not differ from those of emmetropes. Those who became myopic had fewer outdoor/sports activity hours than the emmetropes before, at, and after myopia onset. Myopia onset may influence childrens near work behavior, but the lack of difference before onset argues against a major causative role for near work. Less outdoor/sports activity before myopia onset may exert a stronger influence on development than near work.

Visual acuity of the preschool child: a review

ABSTRACT 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: (1) methods of assessment of visual acuity; (2) visual acuity norms obtained with these tests; (3) reasons for the variations in reported visual acuity norms; (4) variations in referral criteria for vision screenings; (5) testability reported for various visual acuity tests; and (6) 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, STYCAR (Sheridan‐Gardiner) comes closest to meeting these criteria.

Validity of the convergence insufficiency symptom survey: a confirmatory study.

Purpose. The objectives of the present study were to evaluate whether investigator bias influenced the Convergence Insufficiency Symptom Survey (CISS) scores of children with normal binocular vision (NBV) in our original validation study, reevaluate the usefulness of the cutoff score of 16, and reexamine the validity of the CISS. Methods. Six clinical sites participating in the Convergence Insufficiency Treatment Trial (CITT) enrolled 46 children 9 to <18 years with NBV. Examiners masked to the child’s binocular vision status administered the CISS. The mean CISS score was compared with that from the children with NBV in the original, unmasked CISS study and also to that of the 221 symptomatic convergence insufficiency (CI) children enrolled in the CITT. Results. The mean (±standard deviation) CISS score for 46 subjects with NBV was 10.4 (±8.1). This was comparable with our prior unmasked NBV study (mean = 8.1 (±6.2); p = 0.11) but was significantly different from that of the CITT CI group (mean = 29.8 ± 9.0; p < 0.001). Eighty-three percent of these NBV subjects scored <16 on the CISS, which is not statistically different from the 87.5% found in the original unmasked study (p = 0.49). Conclusions. Examiner bias did not affect the CISS scores for subjects with NBV in our prior study. The CISS continues to be a valid instrument for quantifying symptoms in 9 to <18-year-old children. These results also confirm the validity of a cut-point of ≥16 in distinguishing children with symptomatic CI from those with NBV.

Children's Ocular Components and Age, Gender, and Ethnicity.

Purpose. This cross-sectional report includes ocular component data as a function of age, gender, and ethnicity from the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study. Methods. The ocular components of 4881 school-aged children were examined using cycloplegic autorefraction (refractive error), keratometry (corneal curvature), ultrasonography (axial dimensions), and videophakometry (lens curvature). Results. The average age (±SD) was 8.8 ± 2.3 years, and 2457 were girls (50.3%). Sixteen percent were African-American, 14.8% were Asian, 22.9% were Hispanic, 11.6% were Native American, and 34.9% were White. More myopic/less hyperopic refractive error was associated with greater age, especially in Asians, less in Whites and African Americans. Corneal power varied slightly with age, with girls showing a greater mean corneal power. Native-American children had greater corneal toricity with a markedly flatter horizontal corneal power. Anterior chambers were longer with age, and boys had deeper anterior chambers. Native-American children had the shallowest anterior chambers and Whites the deepest. Girls had higher Gullstrand and calculated lens powers than boys. Boys had longer vitreous chambers and axial lengths, and both were longer with age. Native Americans had the longest vitreous chambers and Whites the shortest. Conclusions. Most ocular components showed little clinically meaningful variation by ethnicity. The shallower anterior chambers and deeper vitreous chambers of Native-American children appeared to be offset by flatter corneas. The relatively deeper anterior chambers and shallower vitreous chambers of White children appeared to be offset by steeper corneas. Asian children had more myopic spherical equivalent refractive errors, but for a given refractive error the ocular parameters of Asian children were moderate in value compared with those of other ethnic groups. Asian children may develop longer, myopic eyes more often than other ethnic groups, but the eyes of Asian emmetropes do not appear to be innately longer.

Minus-Lens–Stimulated Accommodative Amplitude Decreases Sigmoidally with Age: A Study of Objectively Measured Accommodative Amplitudes from Age 3

PURPOSE Guidelines for predicting accommodative amplitude by age are often based on subjective push-up test data that overestimate the accommodative response. Studies in which objective measurements were used have defined expected amplitudes for adults, but expected amplitudes for children remain unknown. In this study, objective methods were used to measure accommodative amplitude in a wide age range of individuals, to define the relationship of amplitude and age from age 3. METHODS Accommodative responses were measured in 140 subjects aged 3 to 40 years. Measurements were taken with the Grand Seiko autorefractor (RyuSyo Industrial Co., Ltd., Kagawa, Japan) as the subjects viewed a high-contrast target at 33 cm through minus lenses of increasing power until the responses showed no further increase in accommodation. RESULTS The maximum accommodative amplitude of each subject was plotted by age, and a curvilinear function fit to the data: y = 7.33 - 0.0035(age - 3)(2) (P < 0.001). Tangent analysis of the fit indicated that the accommodative amplitude remained relatively stable until age 20. Data from this study were then pooled with objective amplitudes from previous studies of adults up to age 70. A sigmoidal function was fit to the data: y = 7.083/(1 + e([0.2031(age-36.2)-0.6109])) (P < 0.001). The sigmoidal function indicated relatively stable amplitudes below age 20 years, a rapid linear decline between 20 and 50 years, and a taper to 0 beyond 50 years. CONCLUSIONS These data indicate that accommodative amplitude decreases in a curvilinear manner from 3 to 40 years. When combined with data from previous studies, a sigmoidal function describes the overall trend throughout life with the biggest decrease occurring between 20 and 50 years.

Vision: Myopia and ambient night-time lighting

Myopia is a common affliction (one in four adult Americans is near-sighted), and juvenile-onset myopia is believed to be due to a combination of genetic and environmental factors. Results from animal experiments indicate that light cycles may affect the development of myopia, and Quinn et al. claim to have extended these to humans. They reported a strong association between childhood myopia and night-time lighting before the age of two: there were five times more children with myopia among those who slept with room lights on than in those who slept in the dark, and an intermediate number among those sleeping with a dim night-light. However, we have been unable to find a link between night-time nursery lighting and the development of myopia in a sample of schoolchildren.

The development of accommodation

We investigated the roles that blur, proximity and vergence cues play in the development of accommodation. Accommodative responses to targets incorporating one or more of these cues were measured for four adults and eight infants at 1.5 and 3 months of age using eccentric photorefraction. Adults showed accurate accommodation to blur cues, and variable accommodation with proximity cues alone. Some infants at both ages showed fixed accommodative responses to all stimulus conditions. Others responded consistently in the correct direction for pattern targets at different distances, but made poorer responses when blur was presented in conflict with distance. Binocular viewing improved the accommodative responses in only some infants.