Axial growth and refractive change in white European children and young adults: predictive factors for myopia.

This report describes development of spherical equivalent refraction (SER) and axial length (AL) in two population-based cohorts of white, European children. Predictive factors for myopic growth were explored. Participants were aged 6-7- (n = 390) and 12-13-years (n = 657) at baseline. SER and AL were assessed at baseline and 3, 6 and 9 years prospectively. Between 6 and 16 years: latent growth mixture modelling identified four SER classes (Persistent Emmetropes-PEMM, Persistent Moderate Hyperopes-PMHYP, Persistent High Hyperopes-PHHYP and Emerging Myopes-EMYO) as optimal to characterise refractive progression and two classes to characterise AL. Between 12 and 22-years: five SER classes (PHHYP, PMHYP, PEMM, Low Progressing Myopes-LPMYO and High Progressing Myopes-HPMYO) and four AL classes were identified. EMYO had significantly longer baseline AL (≥ 23.19 mm) (OR 2.5, CI 1.05-5.97) and at least one myopic parent (OR 6.28, CI 1.01-38.93). More myopic SER at 6-7 years (≤ + 0.19D) signalled risk for earlier myopia onset by 10-years in comparison to baseline SER of those who became myopic by 13 or 16 years (p ≤ 0.02). SER and AL progressed more slowly in myopes aged 12-22-years (- 0.16D, 0.15 mm) compared to 6-16-years (- 0.41D, 0.30 mm). These growth trajectories and risk criteria allow prediction of abnormal myopigenic growth and constitute an important resource for developing and testing anti-myopia interventions.

Parents and teachers of children in special education settings value in-school eyecare and written reports of visual status.

OBJECTIVES: To evaluate parent and teacher opinion of the provision of in-school eyecare and jargon-free written reporting of visual status for children in special educational settings. PARTICIPANTS AND METHODS: A nationally-agreed, in-school eyecare framework for children attending special schools which recommends a full eye examination, dispensing of spectacles and provision of a jargon-free written report of visual outcomes to parents and teachers, was provided to 200 children (mean age 10 years, 9 months; 70% male) attending a special school in the UK. The written 'Vision Report' detailed, in lay-language, results from the eye examination and provided practical advice to alleviate the impact of vision difficulties both at home and in the classroom. Following implementation of the framework, parents and teachers completed a feedback questionnaire to determine their opinion of the in-school eye examination and utility of the Vision Report. RESULTS: Parents of 123 participants returned a feedback questionnaire. Eighty-eight participants were represented by the 23 teachers who returned a questionnaire. The in-school eyecare was rated positively for children in special education by 82.4% of parents and 80.9% of teachers. Key benefits included the familiarity of the in-school setting (81.3% of parents and 100% of teachers agree), the convenience of the setting for parents (74.0% of parents and 100% of teachers agree), and the opportunity for teachers to speak directly to eyecare providers regarding a child's visual needs (82.6% of teachers agree). The information provided by the Vision Report was deemed useful day-to-day by 78.3% of parents and 100% of teachers. The majority (80%) of teachers implemented classroom modifications suggested in the report, whereas only 47.9% of parents reported implementation of modifications at home. CONCLUSIONS: Provision of in-school eyecare is valued by parents and teachers of children in special education settings. Jargon-free, written reports of visual status are valued and utilised by parents and teachers. Further support is required to aid parents in implementing vision modifications at home.

Investigation of medication adherence and reasons for poor adherence in patients on long-term glaucoma treatment regimes.

PURPOSE: Long-term treatment adherence for a chronic asymptomatic condition is a demanding task for many patients. Treating progressive glaucoma can also be confounding for physicians, particularly when management relies on assumption of adherence. This study investigated associations between self-reported adherence and frequency of medication changes due to glaucoma progression. METHODS: A total of 128 participants with primary open angle glaucoma were recruited from glaucoma clinics in Flinders Eye Center, South Australia, and completed confidential questionnaires. Information was obtained regarding beliefs about glaucoma and their treatment. Adherence was assessed using the four-item Morisky, Green and Levine Medication Adherence Questionnaire (MGL). Medical records were analyzed for the number of medication changes, due to glaucoma progression. RESULTS: Adherence to topical glaucoma medication was categorized as 'high' in 41.4% (Morisky, Green and Levine (MGL). Data were analyzed for behaviors affecting adherence, history of adherence, and reasons for changed adherence. Chi-squared test demonstrated that there was no significant association noted between adherence and changes in medication regime (χ2 (2,128)=0.968, P=0.915); however, a significantly lower adherence was detected if participants had difficulties with their drop regime (χ2 (2,128)=7.24, P=0.027) or had help with drop insertion (χ2 (1,128)=9.77, P=0.008). CONCLUSION: This study revealed a higher rate of non-adherence than has previously been demonstrated in other studies. This may be attributed to the unique design of the confidential questionnaire and the independent and sympathetic questioning techniques used. Further work to develop a specific glaucoma medication adherence questionnaire would be valuable to enhance glaucoma management.

Risk Factors for Childhood Myopia: Findings From the NICER Study.

PURPOSE: We explored risk factors for myopia in 12- to 13-year-old children in Northern Ireland (NI). METHODS: Stratified random sampling was performed to obtain representation of schools and children. Cycloplegia was achieved using cyclopentolate hydrochloride 1%. Distance autorefraction was measured using the Shin-Nippon SRW-5000 device. Height and weight were measured. Parents and children completed a questionnaire, including questions on parental history of myopia, sociodemographic factors, childhood levels of near vision, and physical activity to identify potential risk factors for myopia. Myopia was defined as spherical equivalent ≤-0.50 diopters (D) in either eye. RESULTS: Data from 661 white children aged 12- to 13-years showed that regular physical activity was associated with a lower estimated prevalence of myopia compared to sedentary lifestyles (odds ratio [OR] = 0.46 adjusted for age, sex, deprivation score, family size, school type, urbanicity; 95% confidence interval [CI], 0.23-0.90; P for trend = 0.027). The odds of myopia were more than 2.5 times higher among children attending academically-selective schools (adjusted OR = 2.66; 95% CI, 1.48-4.78) compared to nonacademically-selective schools. There was no evidence of an effect of urban versus nonurban environment on the odds of myopia. Compared to children with no myopic parents, children with one or both parents being myopic were 2.91 times (95% CI, 1.54-5.52) and 7.79 times (95% CI, 2.93-20.67) more likely to have myopia, respectively. CONCLUSIONS: In NI children, parental history of myopia and type of schooling are important determinants of myopia. The association between myopia and an environmental factor, such as physical activity levels, may provide insight into preventive strategies.

Longitudinal study of spherical refractive error in infantile nystagmus syndrome.

PURPOSE: To explore the onset and progression of spherical refractive error in a population with infantile nystagmus syndrome. METHODS: Retrospective refractive error data were obtained from 147 medical records of children with infantile nystagmus syndrome (albinism n = 98; idiopathic infantile nystagmus n = 49), attending a low vision clinic in Northern Ireland, over a 24 year period (1986-2010). Data were categorised by age to allow for comparisons with published studies. A prospective group of participants with Infantile nystagmus syndrome (INS) [n = 22 (albinism n = 18, idiopathic infantile nystagmus n = 4)] (aged 0-4) were also recruited. Cycloplegic streak retinoscopy was performed biannually, over a 3 year period. Spherical equivalent refractive error and most ametropic meridian were analysed. RESULTS: The mean spherical equivalent refractive errors for albinism and idiopathic infantile nystagmus groups (across all age categories) were hypermetropic, with highest levels demonstrated by the participants with albinism aged 1 ≤ 4 years (Mann-Whitney U test, p = 0.013). Mean most ametropic meridian was highest in the albinism group aged 1 ≤ 12 years (Mann-Whitney U test, p < 0.05). Individual data demonstrated relatively static spherical equivalent refractive errors over time. Prospective participants were hypermetropic at all visits and those with albinism had, on average, higher refractive errors than those with idiopathic infantile nystagmus (IIN). No significant correlations were noted between visual acuity and spherical equivalent refractive errors or most ametropic meridian. CONCLUSIONS: Hypermetropia is the most prevalent spherical refractive error in the INS population, irrespective of level of visual acuity. Individuals with infantile nystagmus syndrome fail to demonstrate typical patterns of emmetropisation, particularly in the presence of albinism.

Investigating the relationship between foveal morphology and refractive error in a population with infantile nystagmus syndrome.

PURPOSE: We explored associations between refractive error and foveal hypoplasia in infantile nystagmus syndrome (INS). METHODS: We recruited 50 participants with INS (albinism n = 33, nonalbinism infantile nystagmus [NAIN] n = 17) aged 4 to 48 years. Cycloplegic refractive error and logMAR acuity were obtained. Spherical equivalent (SER), most ametropic meridian (MAM) refractive error, and better eye acuity (VA) were used for analyses. High resolution spectral-domain optical coherence tomography (SD-OCT) was used to obtain foveal scans, which were graded using the Foveal Hypoplasia Grading Scale. Associations between grades of severity of foveal hypoplasia, and refractive error and VA were explored. RESULTS: Participants with more severe foveal hypoplasia had significantly higher MAMs and SERs (Kruskal-Wallis H test P = 0.005 and P = 0.008, respectively). There were no statistically significant associations between foveal hypoplasia and cylindrical refractive error (Kruskal-Wallis H test P = 0.144). Analyses demonstrated significant differences between participants with albinism or NAIN in terms of SER and MAM (Mann-Whitney U test P = 0.001). There were no statistically significant differences between astigmatic errors between participants with albinism and NAIN. Controlling for the effects of albinism, results demonstrated no significant associations between SER, and MAM and foveal hypoplasia (partial correlation P > 0.05). Poorer visual acuity was associated statistically significantly with more severe foveal hypoplasia (Kruskal-Wallis H test P = 0.001) and with a diagnosis of albinism (Mann-Whitney U test P = 0.001). CONCLUSIONS: Increasing severity of foveal hypoplasia is associated with poorer VA, reflecting reduced cone density in INS. Individuals with INS also demonstrate a significant association between more severe foveal hypoplasia and increasing hyperopia. However, in the absence of albinism, there is no significant relation between refractive outcome and degree of foveal hypoplasia, suggesting that foveal maldevelopment in isolation does not impair significantly the emmetropization process. It likely is that impaired emmetropization evidenced in the albinism group may be attributed to the whole eye effect of albinism.

Profile of anisometropia and aniso-astigmatism in children: prevalence and association with age, ocular biometric measures, and refractive status.

PURPOSE: We describe the profile and associations of anisometropia and aniso-astigmatism in a population-based sample of children. METHODS: The Northern Ireland Childhood Errors of Refraction (NICER) study used a stratified random cluster design to recruit a representative sample of children from schools in Northern Ireland. Examinations included cycloplegic (1% cyclopentolate) autorefraction, and measures of axial length, anterior chamber depth, and corneal curvature. χ(2) tests were used to assess variations in the prevalence of anisometropia and aniso-astigmatism by age group, with logistic regression used to compare odds of anisometropia and aniso-astigmatism with refractive status (myopia, emmetropia, hyperopia). The Mann-Whitney U test was used to examine interocular differences in ocular biometry. RESULTS: Data from 661 white children aged 12 to 13 years (50.5% male) and 389 white children aged 6 to 7 years (49.6% male) are presented. The prevalence of anisometropia ≥1 diopters sphere (DS) did not differ statistically significantly between 6- to 7-year-old (8.5%; 95% confidence interval [CI], 3.9-13.1) and 12- to 13-year-old (9.4%; 95% CI, 5.9-12.9) children. The prevalence of aniso-astigmatism ≥1 diopters cylinder (DC) did not vary statistically significantly between 6- to 7-year-old (7.7%; 95% CI, 4.3-11.2) and 12- to 13-year-old (5.6%; 95% CI, 0.5-8.1) children. Anisometropia and aniso-astigmatism were more common in 12- to 13-year-old children with hyperopia ≥+2 DS. Anisometropic eyes had greater axial length asymmetry than nonanisometropic eyes. Aniso-astigmatic eyes were more asymmetric in axial length and corneal astigmatism than eyes without aniso-astigmatism. CONCLUSIONS: In this population, there is a high prevalence of axial anisometropia and corneal/axial aniso-astigmatism, associated with hyperopia, but whether these relations are causal is unclear. Further work is required to clarify the developmental mechanism behind these associations.

Visual acuity measures do not reliably detect childhood refractive error--an epidemiological study.

PURPOSE: To investigate the utility of uncorrected visual acuity measures in screening for refractive error in white school children aged 6-7-years and 12-13-years. METHODS: The Northern Ireland Childhood Errors of Refraction (NICER) study used a stratified random cluster design to recruit children from schools in Northern Ireland. Detailed eye examinations included assessment of logMAR visual acuity and cycloplegic autorefraction. Spherical equivalent refractive data from the right eye were used to classify significant refractive error as myopia of at least 1DS, hyperopia as greater than +3.50DS and astigmatism as greater than 1.50DC, whether it occurred in isolation or in association with myopia or hyperopia. RESULTS: Results are presented from 661 white 12-13-year-old and 392 white 6-7-year-old school-children. Using a cut-off of uncorrected visual acuity poorer than 0.20 logMAR to detect significant refractive error gave a sensitivity of 50% and specificity of 92% in 6-7-year-olds and 73% and 93% respectively in 12-13-year-olds. In 12-13-year-old children a cut-off of poorer than 0.20 logMAR had a sensitivity of 92% and a specificity of 91% in detecting myopia and a sensitivity of 41% and a specificity of 84% in detecting hyperopia. CONCLUSIONS: Vision screening using logMAR acuity can reliably detect myopia, but not hyperopia or astigmatism in school-age children. Providers of vision screening programs should be cognisant that where detection of uncorrected hyperopic and/or astigmatic refractive error is an aspiration, current UK protocols will not effectively deliver.

Cup-to-disc and arteriole-to-venule ratios in children aged 6-7 and 12-13 years.

PURPOSE: Little data exist detailing the normal cup-to-disc (CD) ratios and arteriole-to-venule (A/V) ratios of school age children. In addition, controversy exists in the literature regarding associations between CD and A/V ratios and visual and biometric parameters. The present study investigates the success rates of obtaining useable optic disc images from the portable Nidek Handheld Non-Mydriatic Fundus Camera (NM-200D) from school-age children and describes the distribution of CD ratios and A/V ratios in children aged 6-7 years of age and 12-13 years of age. In addition, the present study explores associations between CD and A/V ratios and a range of visual function and biometric parameters in children. METHODS: Fundus images were obtained from 195 6-7 year old children and 227 12-13 year old children participating in a wider study of visual function in childhood (Northern Ireland Childhood Errors of Refraction Study or NICER). ImageJ software was used to obtain CD and A/V ratios from the digital images. Visual function measures and biometric parameters were also available for all participants including; cycloplegic refractive error, vision, corneal curvature, axial length, height and weight. RESULTS: One hundred and eighty fundus images (92.3%) from the 6-7 year olds and 194 images (85.5%) from the 12-13 year olds children were considered useable. Analysis (one way anova) demonstrated statistically significant differences between CD ratios and A/V ratios between the age groups. Participants aged 12-13 years had larger CD ratios and smaller A/V ratios (mean CD ratio 0.37 ± 0.09, mean A/V ratio 0.75 ± 0.10) than 6-7 year old participants (mean CD ratio 0.30 ± 0.09, mean A/V ratio 0.78 ± 0.12). No significant associations were noted between CD ratios and A/V ratio and any visual, ocular or biometric parameters. CONCLUSIONS: The present study provides novel normative data on CD and A/V ratios in UK school age children for clinicians in practice.

An evaluation of clinical treatment of convergence insufficiency for children with reading difficulties.

BACKGROUND: The present study investigates two different treatment options for convergence insufficiency CI for a group of children with reading difficulties referred by educational institutes to a specialist eye clinic in Vienna. METHODS: One hundred and thirty four subjects (aged 7-14 years) with reading difficulties were referred from an educational institute in Vienna, Austria for visual assessment. Each child was given either 8Δ base-in reading spectacles (n=51) or computerised home vision therapy (HTS) (n=51). Thirty two participants refused all treatment offered (clinical control group). A full visual assessment including reading speed and accuracy were conducted pre- and post-treatment. RESULTS: Factorial analyses demonstrated statistically significant changes between results obtained for visits 1 and 2 for total reading time, reading error score, amplitude of accommodation and binocular accommodative facility (within subjects effects) (p<0.05). Significant differences were also demonstrated between treatment groups for total reading time, reading error score and binocular accommodative facility (between subjects effects) (p<0.05). CONCLUSIONS: Reading difficulties with no apparent intellectual or psychological foundation may be due to a binocular vision anomaly such as convergence insufficiency. Both the HTS and prismatic correction are highly effective treatment options for convergence insufficiency. Prismatic correction can be considered an effective alternative to HTS.

Refractive and corneal astigmatism in white school children in northern ireland.

PURPOSE: To study the prevalence of and relation between refractive and corneal astigmatism in white school children in Northern Ireland and to describe the association between refractive astigmatism and refractive error. METHODS: Stratified random clustering was used to recruit 1053 white children, 392 aged 6-7 years and 661 aged 12-13 years. Eye examinations included cycloplegic autorefraction and ocular biometric measures of axial length and corneal curvature. RESULTS: The prevalence of refractive astigmatism (≥ 1 DC) did not differ significantly between 6- to 7-year-old children (24%; 95% confidence interval [CI], 19-30) and 12- to 13-year-old children (20%; 95% CI, 14-25). The prevalence of corneal astigmatism (≥ 1 DC) also did not differ significantly between 6- to 7-year-old children (29%; 95% CI, 24-34) and 12- to 13-year-old children (25%; 95% CI, 21-28). While levels of refractive astigmatism and corneal astigmatism were similar, refractive astigmatism was predominantly oblique (76%; 95% CI, 67-85, of 6- to 7-year-olds; 59%; 95% CI, 48-70, of 12- to 13-year-olds), but corneal astigmatism was predominantly with-the-rule (80%; 95% CI, 72-87, of 6- to 7-year-olds; 82%; 95% CI, 74-90, of 12- to 13-year-olds). The prevalence of refractive astigmatism was associated with increasing myopia and hyperopia. CONCLUSIONS: This study is the first to provide robust population-based data on the prevalence of astigmatism in white school children in the United Kingdom. The prevalence of refractive astigmatism and corneal astigmatism is stable between 6 and 7 years and 12 and 13 years, although this finding would need to be confirmed by prospective studies. There is a high prevalence of refractive and corneal astigmatism which is associated with ametropia.

A survey of visual function in an Austrian population of school-age children with reading and writing difficulties.

BACKGROUND: To describe and compare visual function measures of two groups of school age children (6-14 years of age) attending a specialist eyecare practice in Austria; one group referred to the practice from educational assessment centres diagnosed with reading and writing difficulties and the other, a clinical age-matched control group. METHODS: Retrospective clinical data from one group of subjects with reading difficulties (n = 825) and a clinical control group of subjects (n = 328) were examined.Statistical analysis was performed to determine whether any differences existed between visual function measures from each group (refractive error, visual acuity, binocular status, accommodative function and reading speed and accuracy). RESULTS: Statistical analysis using one way ANOVA demonstrated no differences between the two groups in terms of refractive error and the size or direction of heterophoria at distance (p > 0.05). Using predominately one way ANOVA and chi-square analyses, those subjects in the referred group were statistically more likely to have poorer distance visual acuity, an exophoric deviation at near, a lower amplitude of accommodation, reduced accommodative facility, reduced vergence facility, a reduced near point of convergence, a lower AC/A ratio and a slower reading speed than those in the clinical control group (p < 0.05). CONCLUSIONS: This study highlights the high proportions of visual function anomalies in a group of children with reading difficulties in an Austrian population. It confirms the importance of a full assessment of binocular visual status in order to detect and remedy these deficits in order to prevent the visual problems continuing to impact upon educational development.

Profile of refractive errors in cerebral palsy: impact of severity of motor impairment (GMFCS) and CP subtype on refractive outcome.

PURPOSE: To describe refractive status in children and young adults with cerebral palsy (CP) and relate refractive error to standardized measures of type and severity of CP impairment and to ocular dimensions. METHODS: A population-based sample of 118 participants aged 4 to 23 years with CP (mean 11.64 +/- 4.06) and an age-appropriate control group (n = 128; age, 4-16 years; mean, 9.33 +/- 3.52) were recruited. Motor impairment was described with the Gross Motor Function Classification Scale (GMFCS), and subtype was allocated with the Surveillance of Cerebral Palsy in Europe (SCPE). Measures of refractive error were obtained from all participants and ocular biometry from a subgroup with CP. RESULTS: A significantly higher prevalence and magnitude of refractive error was found in the CP group compared to the control group. Axial length and spherical refractive error were strongly related. This relation did not improve with inclusion of corneal data. There was no relation between the presence or magnitude of spherical refractive errors in CP and the level of motor impairment, intellectual impairment, or the presence of communication difficulties. Higher spherical refractive errors were significantly associated with the nonspastic CP subtype. The presence and magnitude of astigmatism were greater when intellectual impairment was more severe, and astigmatic errors were explained by corneal dimensions. Conclusions. High refractive errors are common in CP, pointing to impairment of the emmetropization process. Biometric data support this CONCLUSION: In contrast to other functional vision measures, spherical refractive error is unrelated to CP severity, but those with nonspastic CP tend to demonstrate the most extreme errors in refraction.

Clinical judgement of near pupil responses provides a useful indicator of focusing ability in children with cerebral palsy.

Accommodation is often reduced in cerebral palsy (CP). Knowledge about accommodative facility is valuable when investigating a child's visual needs and developing strategies for education. With normal accommodation, changing focus from distance to near results in pupil constriction. We compared quality of near pupil responses (NPR) with objective measures of accommodative function obtained with dynamic retinoscopy (DR) to investigate the utility of NPR in indicating accommodative facility. NPR and accommodative function of 90 children with CP (56 males, 34 females; median age 11y, range 4-18y) were assessed. A total of 93% of participants had spastic CP (71.3% bilateral involvement, 28.7% hemiplegia). The severity of motor impairment ranged from very mild (n=7) to severe (no independent walking, n=28). NPR was classified subjectively as normal, reduced, or absent and compared with DR measures of accommodative response. A total of 9.8% of pupil responses were judged absent, 25.6% reduced, and 64.6% normal. Participants with reduced or absent pupil responses demonstrated significantly poorer levels of accommodation with DR (one-way analysis of variance p<0.01). Sensitivity and specificity of NPR in identifying participants with reduced accommodation were 83% (95% confidence interval [CI] 65.5-92.4%) and 72% (95% CI 58.4-82.0%) respectively. NPR provides a rapid, useful indicator of accommodative function in children with CP.

Accommodative dysfunction in children with cerebral palsy: a population-based study.

PURPOSE: To determine the prevalence, nature, and degree of accommodative dysfunction among children with different types and severities of cerebral palsy (CP) in Northern Ireland. METHODS: Ninety subjects with CP (aged 4-15 years) were recruited through the Northern Ireland CP Register (NICPR). Modified Nott dynamic retinoscopy was used to measure lag and lead of accommodation at three test distances: 25 cm (4 D), 16.7 cm (6 D), and 10 cm (10 D) with the distance correction in place. Accommodative function was also assessed in an age-matched control group (n = 125) for comparison. Each subject's neurologic status was derived from the NICPR. RESULTS: Children with CP demonstrate significantly reduced accommodative responses compared with their neurologically normal peers. Of the subjects with CP, 57.6% demonstrated an accommodative lag outside normal limits at one or more distances. Reduced accommodative responses were significantly associated with more severe motor and intellectual impairments (ANOVA P = 0.001, P < 0.01, respectively). CONCLUSIONS: Brain injury such as that present in CP has a significant impact on accommodative function. These findings have implications for the optometric care of children with CP and inform our understanding of the impact of early brain injury on visual development.

Accommodative lag using dynamic retinoscopy: age norms for school-age children.

BACKGROUND: Nott dynamic retinoscopy (DR) is a technique that provides an objective, rapid assessment of accommodative function. Presently there are no data available regarding age norms of accommodative function for school-age children using Nott DR. METHODS: Accommodative responses were assessed in a group of 125 school-age children (4 to 15 years of age) using Nott DR. A range of accommodative demands was included [4 D (25 cm), 6 D (16.7 cm), and 10 D (10 cm)]. All the subjects had fully corrected refractive errors and a binocular visual acuity of at least 6/6. RESULTS: Accommodative responses were assessed successfully at each distance with all the subjects (N = 125). A mean overall lag of accommodation was noted with each age group at each distance tested. Regression analysis demonstrated no significant difference in accommodative responses between age groups (p = 0.531 at 4 D, p = 0.062 at 6 D, and p = 0.883 at 10 D). Therefore, results for all the age categories were grouped together to produce a table of normal ranges of accommodation for children aged 4 to 15 years for the three stimuli demands. The mean lag of accommodation was found to be 0.30 +/- 0.39 D at 4 D, 0.74 +/- 0.58 D at 6 D, and 2.50 +/- 1.27 D at 10 D. The normal ranges of accommodation (95% confidence limits) were 2.94 to 4.46 D at 4 D, 4.12 to 6.40 D at 6 D, and 5.02 to 10.00 D at 10 D. CONCLUSIONS: A comprehensive table has been produced detailing the mean lags and normal ranges of accommodative responses expected for school-age children when using Nott DR. These data allow practitioners and researchers to determine whether accommodative responses measured using Nott DR are within normal limits.