The topical azithromycin meibomian gland dysfunction survey: The effect of topical azithromycin on signs and symptoms of meibomian gland dysfunction.

INTRODUCTION: The aim of this study was to assess the long-term effects of topical azithromycin on signs, symptoms and self-management of meibomian gland dysfunction (MGD). METHODS: Forty participants were assessed for MGD and its effect on the fluorescein tear break-up time (FTBUT). Participants were treated with topical azithromycin twice daily for 2 weeks and then once daily for a further 2 weeks. One year after treatment, 31 participants completed a survey assessing pre- and post-treatment effect on symptoms, lifestyle and self-treatment methods. RESULTS: Following treatment, there was a significant reduction in MGD grading from a median of grade 2 to grade 0 (z = 4.40, p < 0.0001) and an increase in FTBUT from a median of 3-8 s (z = 4.75, p < 0.0001). One year afterwards, the survey showed a significant improvement in symptoms (sensitivity to light, grittiness, burning, blurred vision, all p < 0.03) and reduction in required self-treatments (lid wipes, tear substitutes, both p < 0.03). There was also a reduced impact on lifestyle (reading, night driving, computer use and watching television, all p < 0.0001) and in all environmental conditions (all p < 0.0001). CONCLUSIONS: This study confirms the positive effect of topical azithromycin on MGD and shows it has a long-term impact on symptoms, self-treatment methods and lifestyle. This has implications for both chair time and healthcare costs when managing patients with MGD. Pending further clinical trials in a larger population with different demographics, topical azithromycin should be considered by all eyecare practitioners as a viable pharmacological treatment when managing MGD.

Myopia management algorithm. Annexe to the article titled Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute.

Myopia is becoming increasingly common in young generations all over the world, and it is predicted to become the most common cause of blindness and visual impairment in later life in the near future. Because myopia can cause serious complications and vision loss, it is critical to create and prescribe effective myopia treatment solutions that can help prevent or delay the onset and progression of myopia. The scientific understanding of myopia's causes, genetic background, environmental conditions, and various management techniques, including therapies to prevent or postpone its development and slow its progression, is rapidly expanding. However, some significant information gaps exist on this subject, making it difficult to develop an effective intervention plan. As with the creation of this present algorithm, a compromise is to work on best practices and reach consensus among a wide number of specialists. The quick rise in information regarding myopia management may be difficult for the busy eye care provider, but it necessitates a continuing need to evaluate new research and implement it into daily practice. To assist eye care providers in developing these strategies, an algorithm has been proposed that covers all aspects of myopia mitigation and management. The algorithm aims to provide practical assistance in choosing and developing an effective myopia management strategy tailored to the individual child. It incorporates the latest research findings and covers a wide range of modalities, from primary, secondary, and tertiary myopia prevention to interventions that reduce the progression of myopia.

A Cross-Sectional Study of Myopia and Morning Melatonin Status in Northern Irish Adolescent Children.

Purpose: Previous studies have demonstrated an association between melatonin status and both refractive error and axial length in young adult myopes. This study aimed to determine if this relationship extends to a younger adolescent cohort. Methods: Healthy children aged 12-15 years provided morning saliva samples before attending Ulster University (55°N) for cycloplegic autorefraction and axial length measures. Participants completed questionnaires describing recent sleep habits and physical activity. Salivary melatonin was quantified using high-performance liquid chromatography-tandem mass spectrometry. Data collection for all participants occurred over a 1-week period (April 2021). Results: Seventy participants aged 14.3 (95% CI: 14.2-14.5) years were categorised by spherical equivalent refraction [SER] (range: -5.38DS to +1.88DS) into two groups; myopic SER ≤ -0.50DS (n = 22) or nonmyopic -0.50DS < SER ≤ +2.00DS (n = 48). Median morning salivary melatonin levels were 4.52 pg/ml (95% CI: 2.60-6.02) and 4.89 pg/ml (95% CI: 3.18-5.66) for myopic and nonmyopic subjects, respectively, and did not differ significantly between refractive groups (P = 0.91). Melatonin levels were not significantly correlated with SER, axial length, sleep, or activity scores (Spearman's rank, all P > 0.39). Higher levels of physical activity were associated with higher sleep quality (Spearman's rank, ρ = -0.28, P = 0.02). Conclusion: The present study found no significant relationship between morning salivary melatonin levels and refractive error or axial length in young adolescents. This contrasts with outcomes from a previous study of adults with comparable methodology, season of data collection, and geographical location. Prospective studies are needed to understand the discrepancies between adult and childhood findings and evaluate whether melatonin levels in childhood are indicative of an increased risk for future onset of myopia and/or faster axial growth trajectories and myopia progression in established myopes. Future work should opt for a comprehensive dim-light melatonin onset protocol to determine circadian phase.

Relative peripheral hyperopia leads to greater short-term axial length growth in White children with myopia.

PURPOSE: Controversy exists regarding the influence of peripheral visual experience on the onset and progression of childhood myopia. This longitudinal, observational study evaluated the relationship between relative peripheral refraction (RPR) and changes in refractive error and axial length (AL) over 12 months in White children aged 6-7 and 12-13 years with a range of baseline refractive errors. METHODS: Cycloplegic baseline autorefraction at horizontal retinal eccentricities of 0° and ±30° were recorded with the Shin-Nippon NVision-K 5001 while AL was measured using the Zeiss IOLMaster 700. Measurements were repeated after 12 months on a subgroup. Refractive data were transposed into power vectors as mean spherical equivalent (M), J0 and J45 . RPR was calculated by subtracting central from peripheral measurements. Participants were defined as myopic (M ≤ -0.50 D), premyopic (-0.50 D < M ≤ +0.75 D), emmetropic (+0.75 D < M < +2.00 D) or hyperopic (M ≥ +2.00 D). RESULTS: Data were collected from 222 and 245 participants aged 6-7 and 12-13 years, respectively. Myopic eyes demonstrated, on average, more hyperopic RPR. Emmetropes and premyopes displayed emmetropic RPR, and hyperopes showed a myopic RPR. Fifty-six 6- to 7-year-olds and seventy 12- to 13-year-olds contributed 12-month repeated measures. Longitudinal data demonstrated a significant relationship between a more hyperopic RPR in the nasal retina and greater short-term axial elongation in teens with myopia at baseline (ß = 0.69; p = 0.04). Each dioptre of relative peripheral hyperopia in the nasal retina was associated with an additional 0.10 mm (95% CI: 0.02-0.18 mm) annual increase in AL. CONCLUSIONS: Hyperopic RPR in the nasal retina of myopic children is indicative of increased risk for rapid axial elongation and may be a useful metric to support decision-making in myopia management.

An evaluation of the IOLMaster 700 and its agreement with the IOLMaster v3 in children.

PURPOSE: To evaluate the repeatability and reproducibility of the swept-source optical coherence tomographer Zeiss IOLMaster 700 and compare its outputs with those obtained using partial coherence interferometry (Zeiss IOLMaster v3) in a healthy, paediatric population. METHODS: This is a cross-sectional, observational study. Examiner 1 took two sets of biometric measurements (axial length [AL], mean corneal radius of curvature [Kmean ], anterior chamber depth [ACD] and lens thickness [LT]) using the IOLMaster 700, and one set of measurements (AL, Kmean and ACD) using the IOLMaster v3. Examiner 2 took one full set of measurements using the IOLMaster 700. Mean differences and 95% limits of agreement (LOA) were calculated, and Bland and Altman plots used to explore repeatability and reproducibility of the IOLMaster 700 alongside establishing its agreement with the IOLMaster v3. RESULTS: Mean participant age was 7.52 ± 0.58 years. Repeatability analyses demonstrated small mean differences and narrow 95% LOA for AL (0.001, -0.013 to 0.015 mm), Kmean (0.002, -0.020 to 0.024 mm), ACD (-0.003, -0.031 to 0.024 mm) and LT (0.001, -0.024 to 0.026 mm), respectively. Similarly, small mean differences and narrow 95% LOA established excellent reproducibility (AL 0.001, -0.016 to 0.018 mm; Kmean -0.001, -0.027 to 0.025 mm; ACD -0.010, -0.041 to 0.021 mm; LT 0.002, -0.016 to 0.020 mm). The IOLMaster 700 and IOLMaster v3 demonstrated good agreement with small mean differences and narrow 95% LOA (AL 0.009, -0.034 to 0.052 mm; Kmean 0.016, -0.013 to 0.044 mm; ACD 0.134, 0.055 to 0.212 mm). CONCLUSIONS: When used within a paediatric population, these data demonstrate the IOLMaster 700 to be highly repeatable and reproducible for measures of AL, Kmean , ACD and LT. There is excellent inter-instrument agreement between the IOLMaster 700 and IOLMaster v3 for measures of AL and Kmean . ACD measurements show weaker agreement. These data will be useful when considering reports from population-based studies of refractive error and clinical myopia research.

Reliability and validity of the Actiwatch and Clouclip for measuring illumination in real-world conditions.

PURPOSE: To compare real-world measures of illumination obtained with the Actiwatch-2 and Clouclip-M2 with 'gold standard' photometry measures and to evaluate the ability of Actiwatch-2 to correctly identify photometer-defined conditions: scotopic (≤0.01 lux), mesopic (0.02-3 lux), indoor photopic (>3-1,000 lux) and outdoor photopic (>1,000 lux); and Clouclip to correctly identify photometer-defined conditions within its operating range (>1 lux). Inter-device reliability of Clouclip for illumination and viewing distance measures was also investigated. METHODS: A Hagner-S2 photometer was used as reference. Measures of illumination were obtained from a range of real-world conditions. To investigate inter-device reliability, five Clouclips were simultaneously exposed to varied light conditions and object distances. RESULTS: Strong correlations existed between illumination measured with the photometer and both Actiwatch-2 (ρ = 0.99, p < 0.0001) and Clouclip (ρ = 0.99, p < 0.0001). However, both devices underestimated illumination compared to the photometer; disparity increased with increasing illumination and was greater for Actiwatch-2 than Clouclip measures. Actiwatch-2 successfully categorised illumination level (scotopic, mesopic, indoor and outdoor photopic) in 71.2% of cases. Clouclip successfully categorised illumination levels as scotopic/mesopic (≤3 lux) and indoor and outdoor photopic in 100% of cases. Mean differences and limits of agreement (LOA) were 430.92 ± 1,828.74 and 79.35 ± 407.33 lux, between the photometer and Actiwatch-2 and photometer and Clouclip, respectively. The Intra-class Correlation Coefficients for illumination and viewing distance measured with five Clouclips were 0.85 and 0.96, respectively. CONCLUSION: These data illustrate that different Clouclip devices produce comparable measures of viewing distance and illumination in real-world settings. Both Actiwatch-2 and Clouclip underestimate illumination in the field compared to gold standard photometer measures. The disparity increases at higher levels of illumination and the discrepancy was greater for Actiwatch-2 measures. For researchers interested in categorising light exposure, Clouclip classifies illumination levels >2 lux more accurately than Actiwatch-2 but cannot discriminate between scotopic and low mesopic light.

What can anisometropia tell us about eye growth?

BACKGROUND/AIMS: Both eyes of one individual share the same environment and genes. We examined interocular differences in biometry to determine the potential role of other factors in refractive development. METHODS: 362 subjects (6-7 years) from the Northern Ireland Childhood Errors of Refraction study were studied. Cycloplegic autorefraction was measured with a Shin-Nippon open-field autorefractor. Axial length and corneal curvature were measured with a Zeiss IOLMaster. RESULTS: 257 subjects had an interocular difference of <0.50 D (ISO group) and 105 (29%) a difference of ≥0.50 D (ANISO group). Twenty-five subjects (6.9%) had anisometropia ≥1.00 D and 9 (2.5%) had anisometropia ≥1.50 D. The two groups, ISO and ANISO, showed different refractive distributions (p=0.001) with the ISO group showing a nearly Gaussian distribution and the ANISO group showing positive skew, a hyperopic shift and a bi-Gaussian distribution. A marker of emmetropisation is the poor correlation between refraction and corneal curvature seen in older children. There was no significant correlation between refraction and corneal curvature of each eye in the ISO group (r=0.09, p=0.19), but these parameters were significantly correlated in the ANISO group (r=0.28, p=0.004). CONCLUSION: In young children, small degrees of anisometropia (≥0.5 D) are associated with impaired emmetropisation. This suggests that anisometropia is a marker for poorly regulated eye growth, indicating that, in addition to environmental and genetic influences on eye growth, stochastic processes contribute to refractive outcomes.

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.

Comparison of retinoscopy results with and without 1% cyclopentolate in school-aged children.

PURPOSE: This study was designed with the aim of providing practitioners with an evidence base to inform their clinical decision making as to when cycloplegic retinoscopy is necessary and when it might be appropriate to forgo. The study aimed to determine the age at which there ceases to be a clinically significant difference between cycloplegic and non-cycloplegic retinoscopy and whether age, refractive error, habitual spectacle wear and accommodation influence the relationship. METHODS: A single examiner carried out cycloplegic and non-cycloplegic retinoscopy on 128 children stratified into four age groups (6-7, 8-9, 10-12 and 12-13 years). Cycloplegia was achieved using 1% cyclopentolate and retinoscopy carried out after 30 min. The examiner was masked to the lenses used and to habitual spectacle wear. Accommodation was assessed using dynamic retinoscopy prior to cycloplegia. RESULTS: Cycloplegic and non-cycloplegic sphere differed significantly (z = -9.18, p < 0.0001). Although the difference decreased significantly as age increased (χ2  = 16.57, p = 0.0009), cycloplegic retinoscopy revealed more hyperopia than non-cycloplegic retinoscopy in all age groups (p < 0.0001). The difference between cycloplegic and non-cycloplegic results was greater where 'high' hyperopia (≥+2.50DS) was present (F1,6  = 12.86, p = 0.0005), and as hyperopia increased the difference increased (Spearman's ρ = 0.55, p < 0.0001). Neither spectacle wear (p = 0.74) nor accommodation (p = 0.08) influenced the difference between spherical measures. Measures of astigmatic error did not differ significantly (z = -1.59, p = 0.11). A non-cycloplegic sphere ≥+1.50DS was relatively sensitive (87%) and specific (96%) at indicating clinically significant hyperopia (≥+2.50D) as revealed by cycloplegic retinoscopy. CONCLUSIONS: Cyclopentolate 1% does not impact the cylindrical component of the retinoscopy result, but reveals significantly more hyperopia in the spherical component, both statistically and clinically in children aged 6-13 years. Differences between cycloplegic and non-cycloplegic sphere increase significantly with increasing hyperopia, independent of spectacle wear and accommodation. A non-cycloplegic retinoscopy result of ≥+1.50DS may be used by practitioners wishing to identify children aged 6-13 years at risk of clinically significant hyperopia (≥+2.50DS), but cycloplegia is required to accurately ascertain the full spherical error.

Cycloplegia and spectacle prescribing in children: attitudes of UK optometrists.

PURPOSE: To survey a large number of UK-based optometrists, in a variety of settings, to determine current attitudes relating to the use of cycloplegia and spectacle prescribing in children aged ≤11 years. METHODS: One thousand randomly selected members of the College of Optometrists (UK) were invited to complete an electronic questionnaire. The questionnaire was comprised of 42 questions relating to respondent demographics, practitioner use of cycloplegia and attitudes to using cycloplegia to assess childhood refractive error and prescribing spectacles for children aged ≤11 years. RESULTS: Three hundred and eleven practitioners (31%) completed the questionnaire. Practitioners agreed that they are confident carrying out cycloplegic refraction (60%) and instilling cyclopentolate (77%); are not concerned about the time the procedure takes (69%); feel parents are receptive to its use (65%) and are not discouraged by side effects (72%). Most practitioners agreed that they would carry out a cycloplegic refraction in pre-school children (aged 2-4 years) at their first eye exam (34% vs 27%), but would not carry out a cycloplegic refraction in a child of school age (5-7 years: 25% vs 47%, 8-11 years: 12% vs 45%). More recently qualified practitioners are more likely to be proactive in using cycloplegia (Mann-Whitney, p = 0.003). Community practitioners prescribed at slightly lower levels of ametropia in non-strabismic children than those working in a hospital setting both in the present study and in comparison to previously published hospital optometry values, particularly for hyperopia at 1 year of age. CONCLUSIONS: This is the first study to report practitioner use of cycloplegia and attitudes to using cycloplegia to assess childhood refractive error and prescribing spectacles for children in a large number of UK-based optometrists practising in a variety of settings. The majority of practitioners responded in a positive manner to the use of cycloplegia and reported patterns of use which adhere closely to available professional guidance. However, outcomes indicate practitioners may appreciate more comprehensive evidence-based resources to inform their decision-making relating to use of cycloplegia in paediatric examination.

Visual Profile of Children who Passed or Failed the UK School Vision Screening Protocol.

BACKGROUND: We applied the National Screening Committee vision screening protocol [pass criterion monocular acuity ≤ 0.2 LogMAR in both eyes(BE)] to children four to five years old to investigate the visual profile of children who passed/failed. Previous studies have only evaluated those failing. The aim was to derive false positive and negative values, specificity/sensitivity of the vision screening protocol for detecting significant visual defects (strabismus and/or significant refractive error) and the utility of a 'plus blur test' in identifying hyperopia. METHODS: Participants included 294 children (5.2 ± 0.4 yrs). In addition to the vision screening protocol (monocular acuity-3 m crowded Keeler LogMAR letters), acuities were recorded through +2.50D and +4.00D lenses and ocular alignment and cycloplegic refractive error were assessed. Using acuity measures, participants were classed as passing/failing the screening protocol. Each participant was also classed as having a strabismus and/or significant refractive error (hyperopia ≥ +4.00DS; myopia ≤ -0.50DS; astigmatism ≤ -1.50DC; anisometropia ≥ +1.50DS) or no significant visual defects. RESULTS: Of the 284 children who completed all tests, 27.8% failed to achieve 0.2 LogMAR in BE. The acuity pass/fail criterion had a sensitivity of 70.4% and specificity of 82.2% for detecting strabismus and/or significant refractive error. Of those who failed, 51.9% (n = 41/79) had no strabismus and/or significant refractive error (false positives). Of those who passed, 7.8% (n = 16/205) had visual defects (false negatives). The 'plus blur tests' improved sensitivity in detecting significant refractive error (+2.50D & +4.00D 90.7%) but significantly reduced specificity (+2.50D = 65.2%; +4.00D = 60.9%). CONCLUSIONS: School-entry vision screening is reasonably sensitive and specific for detecting strabismus and/or significant refractive error. Most children with visions poorer than 0.2 LogMAR need refractive intervention, and the majority of the remainder are likely false positives for significant visual defects. One in 13 children who pass have either strabismus and/or significant refractive error (7.8%). The inclusion of a 'plus blur test' was not a useful addition to the vision screening protocol.

Intra- and inter- examiner repeatability of cycloplegic retinoscopy among young children.

PURPOSE: To evaluate the intra- and inter-examiner repeatability of cycloplegic retinoscopy in young children aged 4-5 years old. METHODS: Examiner 1 refracted all children in the first sample (n = 108); firstly with masked loose lenses, then using unmasked loose lenses (intra-examiner repeatability). Examiners 1 and 2 refracted all children in the second sample (n = 97) using unmasked loose lenses, blind to the child's refractive error, presence/magnitude of habitual spectacle correction and to each other's findings (inter-examiner repeatability). Refractions were performed on one eye chosen at random. Mean differences, 95% limits of agreement (LOAs) and confidence intervals were calculated for intra- and inter-examiner repeatability of sphere, cylinder and spherical equivalent refraction (SER). RESULTS: Participants had a wide range of refractive errors (-1.50DS to +7.25DS; ≥4.50DC). Mean differences (95% LOAs) were small for both intra- and inter-examiner repeatability [Intra: Sphere 0.00D (-0.85, +0.85D), Cylinder -0.03D (-0.68, +0.62D), SER -0.06D (-0.90, +0.78D); Inter: Sphere -0.08D (-0.92, +0.76D), Cylinder -0.08D (-0.75, +0.59D), SER -0.13D (-0.95, +0.69D). A statistically significant proportional bias was present for intra-examiner repeatability of cylinder (ρ = 0.20, p = 0.04) and SER measurement (ρ = 0.19, p = 0.049). Proportional bias was not present for any other measure (p > 0.12). Examiners agreed on cylinder axis within ±20° in 71% of refractions where astigmatism of -0.75D or higher was present. 80% of intra- and inter-examiner measures fell within ±0.50D for spherical and cylindrical components. CONCLUSIONS: Differences of ±1.00D and ±0.75D or more for spherical and cylindrical measures respectively can be considered significant when performing cycloplegic retinoscopy on young children.

Six Year Refractive Change among White Children and Young Adults: Evidence for Significant Increase in Myopia among White UK Children.

OBJECTIVE: To determine six-year spherical refractive error change among white children and young adults in the UK and evaluate differences in refractive profiles between contemporary Australian children and historical UK data. DESIGN: Population-based prospective study. PARTICIPANTS: The Northern Ireland Childhood Errors of Refraction (NICER) study Phase 1 examined 1068 children in two cohorts aged 6-7 years and 12-13 years. Prospective data for six-year follow-up (Phase 3) are available for 212 12-13 year olds and 226 18-20 year olds in each cohort respectively. METHODS: Cycloplegic refractive error was determined using binocular open-field autorefraction (Shin-Nippon NVision-K 5001, cyclopentolate 1%). Participants were defined by spherical equivalent refraction (SER) as myopic SER ≤-0.50D, emmetropic -0.50D

Comparison of refractive error measures by the IRX3 aberrometer and autorefraction.

PURPOSE: To compare the aberrometry-derived refractive error measurements from the IRX3 aberrometer (Imagine Eyes, Orsay, France) with a standardized measure of refractive error from the Shin-Nippon SRW-5000 (Japan) autorefractor in a large sample of school-aged children. METHODS: Participants were a subgroup of children from the Northern Ireland Childhood Errors of Refraction Study phase 2 (n = 161 9 to 10 years; n = 147 15 to 16 years). Refractive error was measured under cycloplegia (1.0% cyclopentolate HCl) with the IRX3 aberrometer followed by measurement with the Shin-Nippon autorefractor. Mean differences and 95% confidence intervals and limits of agreement were calculated for refractive vector components (M, J0, and J45). RESULTS: Participants had a wide range of refractive error ranging from -6.00 to +8.00 diopters (D) spherical equivalent refraction. Fixed measurement biases (±95% confidence interval) between instruments were small for both groups (9- to 10-year-olds: M, -0.20 ± 0.65 D; J0, -0.005 D; J45, 0.05 D; 15- to 16-year-olds: M, 0.03 ± 0.61 D; J0, -0.04 D; J45, -0.02 D). Statistically significant differences were found between instruments for M and J45 for the 9- to 10-year-old group (p < 0.0001) and for J0 for the 15- to 16-year-old group (p = 0.003). A statistically significant proportional measurement bias was found for the cylindrical components J0 and J45 for both groups (p < 0.0001), but no statistically significant proportional bias was found for M for either group. CONCLUSIONS: This is the first study to explore refractive error measurements from the IRX3 aberrometer in children. The differences between instruments for all refractive components (M, J0, and J45) were small for both groups (<0.25 D) and may not be considered clinically meaningful. Levels of agreement were also comparable to other studies investigating the validity of instruments measuring automated refraction in both adults and children. The results would suggest that these objective techniques produce similar results for assessment of refractive error in children.

Higher order ocular aberrations and their relation to refractive error and ocular biometry in children.

PURPOSE: The interaction between higher order ocular aberrations (HOA) and refractive error is not yet fully understood. This study investigated HOA in relation to refractive error and ocular biometric parameters in a population with a high prevalence of ametropia. METHODS: The HOA were investigated in two cohorts of Caucasian children aged 9 to 10 and 15 to 16 years (n = 313). These aberrations were measured for a 5-mm pupil with the IRX3 aberrometer. Cycloplegic refractive error and ocular biometry measures, including axial length and corneal curvature, also were assessed with the Shin-Nippon SRW-5000 auto-refractor and Zeiss IOLMaster, respectively. Participants were divided into refractive groups for analysis of HOA. RESULTS: The magnitude of total HOA was higher in this population at 0.27 µm (interquartile range [IQR], 0.22-0.32 µm) than other HOA reported in the literature. The profile of HOA was not significantly different across the two age cohorts or across refractive groups, nor did spherical aberration differ significantly with age (Z4° = 0.07 µm for both cohorts). Multivariate linear regression analysis demonstrated spherical aberration was significantly related to axial length (but not refractive grouping), with longer eyes having less positive values of fourth order and root mean square (RMS) spherical aberration. CONCLUSIONS: This study found no significant difference in HOA across refractive groups. The current study also highlights the importance of knowledge of axial length when analyzing HOA.

Higher order aberrations in children with Down syndrome.

PURPOSE: Down syndrome (DS) is associated with ocular abnormalities and reduced visual function. Studies report atypical optical structures in the DS eye such as thinner, steeper corneae and thinner crystalline lenses and, functionally, a degrading influence of the optics on acuity. This study further investigates optical quality in DS by comparing higher order ocular aberrations (HOAs) in DS and control eyes. METHODS: Participants were 44 children with DS (6-16 years) and 209 age-matched controls. All participants were free from corneal or lenticular pathology. HOAs were measured following cycloplegia using Shack-Hartmann aberrometry. HOAs were analyzed over a 3-mm and 5-mm pupil using Zernike polynomials from third-sixth order. Optical quality was explored using Visual Strehl ratios (VSX) and equivalent defocus values. RESULTS: HOAs were measured successfully from 68% of the DS group and 95% of controls. Root mean square of total combined HOAs, third, and sixth orders and coma were significantly greater in the DS group (P < 0.005). Significant differences were found between groups for Zernike coefficients Z3(-3), Z3(3), Z0(4), (P < 0.013). VSX and equivalent defocus values indicated significantly poorer optical quality in DS eyes (P < 0.02). CONCLUSIONS: Children with DS have greater HOAs and reduced central optical quality compared with typically developing children. Whilst the differences in HOAs between the groups reached statistical significance, they were not of pathological proportions and the DS eye maintains relatively good optical quality considering the degree of ametropia and atypical optical structures often found amongst these children. The subtle reduction in optical quality may, however, compound the visuocortical deficits previously reported in DS.