Comparison of proximal and minus lens autorefraction techniques to measure monocular accommodative amplitude.

SIGNIFICANCE: This study provides a faster method for objectively measuring accommodative amplitude with an open-field autorefractor in a research setting. PURPOSE: Objective measures of accommodative amplitude with an autorefractor take time because of the numerous stimulus demands tested. This study compares protocols using different amounts and types of demands to shorten the process. METHODS: One hundred participants were recruited for four age bins (5 to 9, 10 to 14, 15 to 19, and 20 to 24 years) and monocular amplitude measured with an autorefractor using three protocols: proximal, proximal-lens (letter), and proximal-lens (picture). For proximal, measurements were taken as participants viewed a 0.9 mm "E" placed at 13 demands (40 to 3.3 cm = 2.5 to 30 D). The other protocols used a target (either the "E" or a detailed picture) placed at 33 and 12.5 cm followed by 12.5 cm with a series of lenses (-2, -4, and -5.5 D). Adjustments were made for lens effectivity for the three lens conditions, which were thus 9.6, 11.1, and 12.0 D for individuals without additional spectacle lenses. Accommodative amplitude was defined as the greatest response measured with each technique. One-way analysis of variance was used to compare group mean amplitudes across protocols and differences between letter protocols by age bin. RESULTS: Amplitudes were significantly different between protocols (p < 0.001), with proximal having higher amplitudes (mean ± standard deviation, 8.04 ± 1.70 D) compared with both proximal-lens protocols (letter, 7.48 ± 1.42 D; picture, 7.43 ± 1.42 D) by post hoc Tukey analysis. Differences in amplitude between the proximal and proximal-lens (letter) protocol were different by age group (p = 0 .003), with the youngest group having larger differences (1.14 ± 1.58 D) than the oldest groups (0.17 ± 0.58 and 0.29 ± 0.48 D, respectively) by post hoc Tukey analysis. CONCLUSIONS: The proximal-lens protocols took less time and identified the maximum accommodative amplitude in participants aged 15 to 24 years; however, they may underestimate true amplitude in younger children.

Visual Acuity Prediction Based on Different Refraction Types For Patients With Down Syndrome.

Purpose: The purpose of this study was to determine if control observers can be used as surrogates to predict visual acuity (VA) of patients with Down syndrome (DS). Methods: Thirty adults with DS were enrolled in a clinical trial testing three refraction types: clinical refraction and two using wavefront aberration measures to optimize the metrics pupil fraction tessellated (PFSt) and visual Strehl ratio (VSX). Monocular VA was obtained through habitual refractions and each experimental refraction type. Five controls without DS viewed acuity charts simulating the retinal image produced when the corrections for each DS eye are worn, performing VA and scoring image quality of each chart. Group median VA (DS versus controls) were compared for each refraction type, and control image quality scores were compared to corresponding VA across refraction types. Results: Median VA for participants with DS ranged from 0.46 logMAR (interquartile range [IQR] = 0.32 to 0.54) with habitual correction to 0.36 logMAR (IQR = 0.28 to 0.54) with VSX, whereas controls ranged from 0.37 logMAR (IQR = 0.29 to 0.42) with habitual correction to 0.01 logMAR (IQR = -0.02 to 0.05) with VSX. Overall image quality scores were best for PFSt and VSX and showed a strong linear relationship with control VA (r = -0.91, P < 0.001), and a lesser correlation with DS VA (r = -0.33, P < 0.001). Conclusions: Using surrogate observers to judge image quality simulations of eyes with DS did not predict actual VA, suggesting additional, non-optical factors may be limiting VA in individuals with DS. Translational Relevance: Findings may guide clinical refraction practices for patients with DS.

Dioptric differences between clinically determined and metric-optimised refractions for adults with Down syndrome.

PURPOSE: Refractions based on the optimisation of single-value wavefront-derived metrics may help determine appropriate corrections for individuals with Down syndrome where clinical techniques fall short. This study compared dioptric differences between refractions obtained using standard clinical techniques and two metric-optimised methods: visual Strehl ratio (VSX) and pupil fraction tessellated (PFSt), and investigated characteristics that may contribute to the differences between refraction types. METHODS: Thirty adults with Down syndrome (age = 29 ± 10 years) participated. Three refractive corrections (VSX, PFSt and clinical) were determined and converted to vector notation (M, J0 , J45 ) to calculate the dioptric difference between pairings of each type using a mixed model repeated measures approach. Linear correlations and multivariable regression were performed to examine the relationship between dioptric differences and the following participant characteristics: higher order root mean square (RMS) for a 4 mm pupil diameter, spherical equivalent refractive error and Vineland Adaptive Behavior Scales (a measure of developmental ability). RESULTS: The least squares mean estimates (standard error) of the dioptric differences for each pairing were as follows: VSX versus PFSt = 0.51 D (0.11); VSX versus clinical = 1.19 D (0.11) and PFSt versus clinical = 1.04 D (0.11). There was a statistically significant difference in the dioptric differences between the clinical refraction and each of the metric-optimised refractions (p < 0.001). Increased dioptric differences in refraction were correlated with increased higher order RMS (R = 0.64, p < 0.001 [VSX vs. clinical] and R = 0.47, p < 0.001 [PFSt vs. clinical]) as well as increased myopic spherical equivalent refractive error (R = 0.37, p = 0.004 [VSX vs. clinical] and R = 0.51, p < 0.001 [PFSt vs. clinical]). CONCLUSIONS: The observed differences in refraction demonstrate that a significant portion of the refractive uncertainty is related to increased higher order aberrations and myopic refractive error. Methodology surrounding clinical techniques and metric-optimisation based on wavefront aberrometry may explain the difference in refractive endpoints.

Evaluation of the SpotChecks contrast sensitivity test in children.

PURPOSE: The purpose of this study was to determine intrasession repeatability of a worksheet style contrast sensitivity test (SpotChecks) in children and agreement with an established contrast sensitivity test (Pelli-Robson). METHODS: Forty-three children aged 4 to 12 years participated in this single visit study that included two administrations of the SpotChecks binocularly, a single administration of the Pelli-Robson test and other measures of visual performance such as high-contrast visual acuity. Test order was randomised, and participants wore their habitual correction (39 unaided, 4 wearing glasses) for testing. Bland-Altman plots were used to assess the test-retest repeatability of SpotChecks and its agreement with the Pelli-Robson test. Multiple linear regressions were performed to evaluate whether contrast sensitivity was related to participant characteristics such as age, sex and near binocular visual acuity. RESULTS: The mean difference in log contrast sensitivity (logCS) between two administrations of the SpotChecks was 0.01, with a coefficient of repeatability (1.96*SD of differences) of 0.14 logCS. The mean difference between SpotChecks and Pelli-Robson was 0.00 logCS with 95% limits of agreement of -0.19 to +0.20. For both tests, a statistically significant increase in logCS was associated with age (slopes were 0.02 logCS/year, p < 0.001 and 0.01 logCS/year, p = 0.02 for the SpotChecks and Pelli-Robson tests, respectively). CONCLUSIONS: The SpotChecks test shows good intrasession repeatability and excellent agreement with the Pelli-Robson test in children. Contrast sensitivity showed an increase in logCS with age in children for both tests.

Ciliary muscle thickness in adults with Down syndrome.

PURPOSE: The relationship between ciliary muscle thickness (CMT), age and refractive error was investigated to determine if CMT, like other anterior ocular anatomy, differs in adults with Down syndrome (DS). METHODS: The CMT of 33 adults with DS was imaged using anterior segment optical coherence tomography. Images from the right eye obtained 45 minutes after cycloplegia (1% tropicamide, 2.5% phenylephrine) were analysed to calculate thickness at 1, 2 and 3 mm posterior to the scleral spur (CMT1, CMT2, CMT3), maximum thickness (CMTMAX) and apical thickness (AT = CMT1 - CMT2). Spherical equivalent refractive error was determined by clinical refraction using both non-dilated and dilated measures. Multivariate regression analysis evaluated the relationship between CMT and refractive error while controlling for subject age. RESULTS: Images were analysed from 26 subjects (mean age (SD) 29 years; mean refractive error (SD): -0.90 (5.03) D, range: -15.75 to +5.13D). Mean (SD) CMT decreased with posterior position (CMT1: 804 (83) µm; CMT2: 543 (131) µm; CMT3: 312 (100) µm). Mean (SD) CMTMAX and AT was 869 (57) µm and 260 (84) µm, respectively. There was a significant linear correlation indicating thinning CMT with increasing age for CMT1 and CMT2 (p ≤0.05). CMT2 and CMT3 had a significant negative correlation (thicker muscle with increasing myopic refractive error) (p ≤0.01). AT had a significant positive correlation (thicker muscle with increasing hyperopic refractive error) (p <0.01). CONCLUSIONS: Ciliary muscle thickness in participants with DS was found to be in a similar range with similar refractive error trends to previous reports of individuals without DS. However, it is important to note that the refractive error trends were driven by individuals with moderate to high levels of myopia.

Visual Acuity Outcomes in a Randomized Trial of Wavefront Metric-optimized Refractions in Adults with Down Syndrome.

SIGNIFICANCE: This study reports visual acuity outcomes from a clinical trial investigating an objective refraction strategy that may provide a useful tool for practitioners needing additional strategies to identify refractive corrections for adults with intellectual disability. PURPOSE: Determining refractions for individuals with Down syndrome is challenging because of the presence of elevated refractive error, optical aberrations, and cognitive impairment. This randomized clinical trial evaluated the performance of spectacle corrections determined using clinical techniques and objective refractions derived from wavefront aberration measures. METHODS: Thirty adults with Down syndrome had a clinical refraction determined by a single expert examiner using pre-dilation and post-dilation techniques appropriate for this population. Objective refractions were determined from dilated wavefront aberration measures that were processed post-visit to identify refractions that optimized each of two image quality metrics: pupil fraction tessellated and visual Strehl ratio in the spatial domain. The three refractions were dispensed in random order and worn for 2 months each. The primary outcome measure, binocular visual acuity, was obtained by a masked examiner administering a distance logMAR acuity test. To compare treatment types, mean acuity was compared using a two-sided type 3 F test of the treatment effect in a linear mixed-effects regression model, where the final model included fixed effects for treatment, period (1, 2, or 3), and first-order carryover effects. RESULTS: The 2-month estimated least square means in binocular visual acuity (logMAR) were 0.34 (95% confidence interval [CI], 0.25 to 0.39) for clinical refractions, 0.31 (95% CI, 0.25 to 0.36) for pupil fraction tesselated refractions, and 0.33 (95% CI, 0.27 to 0.38) for visual Strehl ratio refractions. No statistically significant treatment effect was observed (F = 1.10, P = .34). CONCLUSIONS: Objective refractions derived from dilated wavefront aberration measures resulted in acuity similar to expert clinician-derived refractions, suggesting that the objective method may be a suitable alternative for patients with Down syndrome.

Opportunities, barriers, and recommendations in down syndrome research.

BACKGROUND: Recent advances in medical care have increased life expectancy and improved the quality of life for people with Down syndrome (DS). These advances are the result of both pre-clinical and clinical research but much about DS is still poorly understood. In 2020, the NIH announced their plan to update their DS research plan and requested input from the scientific and advocacy community. OBJECTIVE: The National Down Syndrome Society (NDSS) and the LuMind IDSC Foundation worked together with scientific and medical experts to develop recommendations for the NIH research plan. METHODS: NDSS and LuMind IDSC assembled over 50 experts across multiple disciplines and organized them in eleven working groups focused on specific issues for people with DS. RESULTS: This review article summarizes the research gaps and recommendations that have the potential to improve the health and quality of life for people with DS within the next decade. CONCLUSIONS: This review highlights many of the scientific gaps that exist in DS research. Based on these gaps, a multidisciplinary group of DS experts has made recommendations to advance DS research. This paper may also aid policymakers and the DS community to build a comprehensive national DS research strategy.

A Randomized Trial of Objective Spectacle Prescriptions for Adults with Down Syndrome: Baseline Data and Methods.

SIGNIFICANCE: It is difficult to determine the most efficacious refractive correction for individuals with Down syndrome using routine clinical techniques. New objective methods that optimize spectacle corrections for this population may reduce limitations on daily living by improving visual quality. PURPOSE: This article describes the methods and baseline characteristics of study participants in a National Eye Institute-sponsored clinical trial to evaluate objectively derived spectacle corrections in adults with Down syndrome. Intersession repeatability of the primary outcome measure (distance visual acuity) is also reported. METHODS: Adults with Down syndrome were enrolled into a nine-visit study to compare clinically derived spectacle corrections and two different objective spectacle corrections derived from wavefront aberration data. Spectacle corrections were randomized and dispensed for 2 months each. Distance visual acuity was measured with a Bailey-Lovie-style chart. Intersession repeatability of acuity was established by performing difference versus mean analysis from binocular acuity measures obtained through habitual corrections at visits 1 and 2. RESULTS: Thirty adults (mean ± standard deviation age, 29 ± 10 years) with a large range of refractive errors were enrolled. Presenting visual acuity at visit 1 was reduced (right eye, 0.47 ± 0.20 logMAR; left eye, 0.42 ± 0.17 logMAR). The mean difference between visits 1 and 2 was 0.02 ± 0.06 logMAR, with a coefficient of repeatability (1.96 × within-subject standard deviation) of 0.12 logMAR. CONCLUSIONS: This study seeks to investigate new strategies to determine optical corrections that may reduce commonly observed visual deficits in individuals with Down syndrome. The good intersession repeatability of acuity found in this study (six letters) indicates that, despite the presence of reduced acuity, adults with Down syndrome performed the outcome measure for this clinical trial reliably.

Understanding the Impact of Individual Perceived Image Quality Features on Visual Performance.

Purpose: This study aimed to quantify the impact of blur, contrast, and ghosting on perceived overall image quality (IQ) as well as resultant predicted visual acuity, utilizing simulated acuity charts from objective refraction among eyes of individuals with Down syndrome (DS). Methods: Acuity charts were produced, simulating the retinal image when applying 16 different metric-derived sphero-cylindrical refractions for each eye of 30 adult patients with DS. Fourteen dilated adult observers (normal vision) viewed subsets of logMAR acuity charts displayed on an LCD monitor monocularly through a unit magnification 3-mm aperture telescope. Observers rated features blur, ghosting, and contrast on 10-point scales (10 = poorest) and overall IQ on a 0- to 100-point scale (100 = best) and read each chart until five total letters were missed (logMAR technique). Mixed modeling was used to estimate feature influence on overall perceived IQ and relative acuity (compared with an unaberrated chart), separately. Results: Perceived IQ spanned the entire scale (mean = 59 ± 22) and average reduction in relative acuity was two lines (0.2 ± 0.14 logMAR). Perceived blur, ghosting, and contrast were individually correlated with overall IQ and relative acuity. Blur, contrast, and ghosting exert unique effects on overall perceived IQ (P < 0.05). Blur (b = -.009, P < 0.001) and ghosting (b = -.003, P < 0.001) influence relative acuity over and beyond their effects on overall IQ (b = .001, P < 0.0001) and contrast. Conclusions: Objectively identified refractions would ideally provide high contrast, low blur, and low ghosting. These data suggest that blur and ghosting may be given priority over contrast when improving acuity is the goal. Translational Relevance: Findings may guide objective refraction in clinical care.

Impact of Pupil Diameter on Objective Refraction Determination and Predicted Visual Acuity.

PURPOSE: Objective refraction based on wavefront aberration measures is a potential tool for patients unable to participate in a subjective refraction, but the selection of a single pupil diameter for determination of the objective refraction may pose challenges. The purpose of this study was to investigate the impact of pupil diameter on determination of objective refractions for adults with and without Down syndrome (DS) and predicted change in acuity with increasing pupil diameter. METHODS: Wavefront error was obtained from 27 adults with DS and 24 controls, and metric-optimized refractions were identified for 4- and 6-mm pupil diameters. Total dioptric difference between refractions for the two pupil sizes was calculated, and repeated measures analysis of variance was used to evaluate differences in refractions. Next, five control observers read acuity charts produced to simulate image quality of each subject if the same refraction was applied for both a 4- and 6-mm pupil diameter. A comparison of acuity with performance on a clear chart was used to calculate letters lost for each chart. Repeated measures analysis of variance was used to test for differences in letters lost from 4- and 6-mm diameters. RESULTS: The dioptric difference between refractions for 4- and 6-mm pupils was significantly greater in subjects with DS (0.51 diopters vs. 0.19 diopters, P = 0.0012). Letters lost for predicted acuity was less for the 4-mm diameter than 6 mm for charts representing DS eyes (6.5 letters vs. 11 letters, P < 0.0001), as well as for typical eyes (4.5 letters vs. 8 letters, P < 0.0001). CONCLUSIONS: Differences between refractions by pupil diameter were similar to the repeatability of subjective refraction. Visual acuity differences were clinically small, suggesting similar performance for objective refractions with increasing pupil diameter. TRANSLATIONAL RELEVANCE: This work quantifies the potential impact of pupil diameter change on the performance of wavefront optimized refractions in clinical patients.

Application of Topographical Keratoconus Detection Metrics to Eyes of Individuals with Down Syndrome.

SIGNIFICANCE: The challenges associated with clinical assessment of individuals with Down syndrome contribute to a wide range of estimates on the prevalence of keratoconus in the Down syndrome population. This work focuses on two topographical indices previously identified with keratoconus detection, applying them to a topographical data set meeting strict sampling criteria. PURPOSE: The purpose of this study was to quantify the level of keratoconus-like topographical morphology in a large sample of eyes from individuals with Down syndrome, as identified by two keratoconus detection metrics: inferior-superior dioptric asymmetry (I-S) and KISA%. Severity of the asymmetry was also cast within the context of established Collaborative Longitudinal Evaluation of Keratoconus study disease severity classification criteria. METHODS: Corneal topography data on both eyes of 140 subjects with Down syndrome and 138 control subjects were collected. Both I-S and KISA% were calculated from the topography data of eyes with sufficient sampling. Steep and flat keratometry data are reported for subjects with measurements on both eyes in the context of values recorded by the Collaborative Longitudinal Evaluation of Keratoconus study in frank keratoconus to examine within-eye and between-eye asymmetry and severity. RESULTS: Keratoconus detection thresholds were exceeded in 20.8% of the eyes of subjects with Down syndrome and 2.2% of the eyes of controls using I-S and 11.8% of the eyes of subjects with Down syndrome and 0.0% of the eyes of controls using KISA%. Examination of the level of intraeye difference between flat and steep keratometry data for individuals with Down syndrome detected as having corneal morphology consistent with moderate keratoconus yields an average of 1.81 D of toricity, whereas the Collaborative Longitudinal Evaluation of Keratoconus study reported 3.28 D of toricity. CONCLUSIONS: Morphology consistent with keratoconus as codified in the detection metrics I-S and KISA% is present in a large percentage of the eyes of individuals with Down syndrome. Differences were observed in the distribution of severity of corneal morphology in individuals with Down syndrome and the keratoconus population at large.

Comparison of Dynamic Retinoscopy and Autorefraction for Measurement of Accommodative Amplitude.

SIGNIFICANCE: This study promotes the use of dynamic retinoscopy to obtain objective measures of accommodative amplitude (AA) in the clinical setting in lieu of the subjective push-up technique. PURPOSE: This study compared the agreement between open-field autorefraction and a modified dynamic retinoscopy for the objective measurement of AA. METHODS: Accommodative amplitude was measured using two objective techniques for subjects aged 5 to 60 years. Test order was randomized and monocular AA was measured as subjects viewed printed letters 0.9 mm in height with their dominant eye and distance refraction. For retinoscopy, subjects held a near rod and viewed the target at the nearest (most proximal) point of clear vision. The examiner then performed dynamic retinoscopy along the horizontal meridian and identified the physical location of neutrality of the reflex, which was converted to AA in diopters. Autorefraction was performed obtaining repeated measures of refraction beginning from a target demand of 2.5 D and increasing in discrete steps until there was no subsequent increase in accommodative response. Refractions were converted to power in the horizontal meridian and expressed as accommodation in diopters with the maximal value termed the AA. Distance overrefractions were measured for both techniques to adjust AA for any uncorrected refractive error. Difference versus mean analysis was used to compare agreement between tests. RESULTS: The 95% limits of agreement between techniques were calculated after removal of two young outliers who responded poorly to one of the techniques. The overall mean difference for 95 subjects was 0.02 ± 0.97 D, with limits of agreement spanning -1.87 to 1.92 D. No significant linear relationship between the magnitude of the AA and the differences between techniques was observed. CONCLUSIONS: Agreement between dynamic retinoscopy and open-field autorefraction was less than 2 D with no systematic bias, suggesting that dynamic retinoscopy may be a suitable clinical technique to measure objective AA.

Image Quality Metric Derived Refractions Predicted to Improve Visual Acuity Beyond Habitual Refraction for Patients With Down Syndrome.

PURPOSE: To determine which optimized image quality metric (IQM) refractions provide the best predicted visual acuity (VA). METHODS: Autorefraction (AR), habitual refraction (spectacles, n = 23; unaided, n = 7), and dilated wavefront error (WFE) were obtained from 30 subjects with Down syndrome (DS; mean age, 30 years; range, 18-50). For each eye, the resultant metric value for 16 IQMs was calculated after >25000 sphero-cylindrical combinations of refraction were added to the measured WFE to generate residual WFE. The single refraction corresponding to each of the 16 optimized IQMs per eye was selected and used to generate acuity charts. Charts also were created for AR, habitual refraction, and a theoretical zeroing of all lower-order aberrations, and grouped into 10 sets with a clear chart in each set. Dilated controls (five observers per set) read each chart until five letters were missed on a high contrast monitor through a unit magnification telescope with a 3 mm pupil aperture. Average letters lost for the five observers for each chart was used to rank the IQMs for each DS eye. RESULTS: Average acuity for the best performing refraction for all DS eyes was within five letters (0.11 ± 0.05 logMAR) of the clear chart acuity. Optimized IQM refractions had ∼3.5 lines mean improvement from the habitual refraction (0.37 ± 0.22 logMAR, P < 0.001). Three metrics (Visual Strehl Ratio [VSX], VSX computed in frequency domain [VSMTF], and standard deviation of intensity values [STD]) identified refractions that were ranked first, or within 0.09 logMAR of first, in >98% of the eyes. CONCLUSIONS: Optimized IQM refraction is predicted to improve VA in DS eyes based on control observers reading simulated charts. TRANSLATIONAL RELEVANCE: Refractions identified through optimization of IQM may bypass some of the challenges of current refraction techniques for patients with DS. The optimized refractions are predicted to provide better VA compared to their habitual correction.

Impact of Visual Cues on the Magnitude and Variability of the Accommodative Response in Children With Emmetropia and Uncorrected Hyperopia and Adults.

Purpose: We investigated the effect of blur and disparity cues on accommodative accuracy (lag) and variability (time [RMS] and frequency domain [LFC]) in the developing visual system. Methods: A total of 59 children (3-9 years, spherical equivalent refractive error [RE] = -0.3- +4.91 diopters [D]) and 10 adults (23-31 years, RE = -0.37-+1.15D) participated. Accommodation was measured in the right eye for 1 minute at 100 and 33 cm using photorefraction (25 Hz) for three conditions: blur + disparity (binocular, 20/50 optotypes), blur-only (monocular, 20/50 optotypes), disparity-only (binocular, difference-of-Gaussian stimulus). The effect blur and disparity cues have on accommodative accuracy, RMS, and LFC was assessed. Results: Lag, RMS, and LFC increased (P < 0.001) from 100 to 33 cm for each condition in children and adults. In children, accommodation was most accurate and stable when blur and disparity cues remained in the stimulus and became significantly less accurate and more variable (P < 0.001) when blur or disparity cues were removed at 33 cm. In adults, accommodation was significantly less accurate and more variable only when blur was removed from the stimulus (P < 0.022). Children with RE matched to adults had less accurate and more variable accommodative responses at near than adults when cues were removed (P ≤ 0.02). Conclusions: In children and adults, an increase in RMS and LFC is related to an increase in accommodative lag. Children's accommodative systems do not compensate as efficiently as adults when blur and disparity cues are removed, suggesting children <10 years old do not have a mature afferent visual pathway.

Evaluating the use of a temperature sensor to monitor spectacle compliance in warm versus cold climates.

BACKGROUND: This study investigates the utility of a temperature sensor data logger to monitor spectacle compliance for future application in research and clinical settings. Specifically, the question of whether warm versus cold climates negatively impact accuracy of the sensor to monitor spectacle wear is investigated. METHODS: Fifty adults from Houston, Texas (summer) and 40 adults from Columbus, Ohio (winter) wore a thermosensor on their spectacles for one week while keeping wear-time logs. Temperatures during reported spectacle wear (ON) were compared to temperatures during non-wear (OFF) between sites. Two methods to approximate wear time were evaluated by percent error with respect to subject-reported wear time. Method 1 filtered temperatures, classifying the range of 28.4 to 35.2°C as wear. Method 2 utilised examiners interpreting temperature versus time plots. Separate analysis of periods of reported outdoor wear was performed to identify the percentage of time examiners correctly identified wear. RESULTS: Group mean ON temperatures did not differ between sites (p = 0.72), but group mean OFF temperatures were significantly warmer in Houston (Houston: 24.7 ± 2.0°C, Columbus: 20.3 ± 2.1°C; p < 0.0001). Median percent error of the filtering technique to approximate subject reported wear time was 4 per cent for Houston and -8 per cent for Columbus. Median percent error for examiner 1: Houston 1 per cent, Columbus 0 per cent; median percent error for examiner 2: Houston 3 per cent, Columbus 0 per cent. Houston outdoor wear was correctly identified 88 and 97 per cent of the time by the examiners versus 79 and 81 per cent for Columbus. CONCLUSION: Despite environmental temperature differences, measured temperatures during spectacle wear were similar across subjects and median percent error was less than 10 per cent for both wear time approximation methods. The device studied was effective for objectively monitoring spectacle wear in both warm and cold climates with the caveat that subjects spent the majority of time indoors.

Accommodative accuracy by retinoscopy versus autorefraction spherical equivalent or horizontal meridian power.

BACKGROUND: To assess agreement between accommodative lag by monocular estimation method (MEM) retinoscopy and Nott retinoscopy compared to open-field autorefraction using spherical equivalent versus power in the 180 meridian for both children and adults. METHODS: Twenty-six children aged 7-16 years (mean: 9.9 ± 2.3) and 27 adults aged 22-29 years (mean: 24.2 ± 1.7) participated. Accommodative lag was measured by examiners with autorefraction and separate examiners using MEM and Nott retinoscopy while subjects viewed 6/18 letters at 33 cm. Five measures of autorefraction were averaged with vector analysis and both power in the 180 meridian and spherical equivalent was determined. Two-factor repeated measures analysis of variance and the mean difference and 95 per cent limits of agreement were calculated. RESULTS: Mean (standard deviation) lag for each technique was: MEM = 0.69 (0.52) D, Nott = 0.62 (0.51) D, autorefraction in 180 = 0.66 (0.50) D and autorefraction spherical equivalent = 0.60 (0.46) D. Lag did not vary across techniques (p = 0.48), but children did have smaller lags than adults (p < 0.001) and greater amounts of uncorrected astigmatism (0.61 ± 0.09 D versus 0.42 ± 0.08 D, p = 0.02). There was no significant interaction between age group and technique (p = 0.74). Mean differences between techniques were small, ranging from -0.14 to +0.06 D. Ninety-five per cent limits of agreement ranged from ±0.80 to ±1.33 around the mean with the narrowest ranges found for comparisons made to autorefraction in 180. Limits of agreement were also narrowest in children as compared to adults with similar mean differences between age groups. CONCLUSIONS: This study demonstrates the mean agreement between autorefraction and retinoscopic techniques is centred on zero (no bias) in both children and adults. The range of agreement becomes narrower when autorefraction power in the 180 is calculated, even for a sample of subjects with moderately small amounts of uncorrected astigmatism.

Blur Detection, Depth of Field, and Accommodation in Emmetropic and Hyperopic Children.

SIGNIFICANCE: Our results demonstrate that blur detection thresholds are elevated in young children compared with adults, and poorer blur detection thresholds are significantly correlated with the magnitude of accommodative microfluctuations. Given that accommodative microfluctuations are greater with greater accommodative responses, these findings may have implications for young uncorrected hyperopes. PURPOSE: This study investigated the association between subjective blur detection thresholds and accommodative microfluctuations in children 3 years to younger than 10 years old and adults. METHODS: Blur detection thresholds were determined in 49 children with habitually uncorrected refractive error (+0.06 to +4.91 diopters [D] spherical equivalent) and 10 habitually uncorrected adults (+0.08 to +1.51 D spherical equivalent) using a custom blur chart with 1° sized optotypes at 33 cm. Letters were blurred by convolution using a Gaussian kernel (SDs of 0.71 to 11.31 arc minutes in √2 steps). Subjective depth of field was determined in subjects 6 years or older and adults. Accommodative microfluctuations, pupils, and lag were measured using infrared photorefraction (25 Hz). RESULTS: Children had greater blur detection thresholds (P < .001), accommodative microfluctuations (P = .001), and depth of field (P < .001) than adults. In children, increased blur detection thresholds were associated with increased accommodative microfluctuations (P < .001), increased uncorrected hyperopia (P = .01), decreased age (P < .001), and decreased pupil size (P = .01). In a multiple linear regression analysis, blur detection thresholds were associated with accommodative microfluctuations (P < .001) and age (P < .001). Increased accommodative microfluctuations were associated with increased uncorrected hyperopia (P = .004) and decreased pupil size (P = .003) and independently associated with uncorrected hyperopia (P = .001) and pupil size (P = .003) when controlling for age and lag. CONCLUSIONS: Children did not have adult-like blur detection thresholds or depth of field. Increased accommodative microfluctuations and decreased age were independently associated with greater blur detection thresholds in children 3 years to younger than 10 years. Larger amounts of uncorrected hyperopia in children appear to increase blur detection thresholds because the greater accommodative demand and resulting response increase accommodative microfluctuations.

Repeatability of Monocular Acuity Testing in Adults with and without Down Syndrome.

PURPOSE: Individuals with Down syndrome may experience greater difficulty reliably performing visual acuity (VA) tests because of intellectual disability and limitations in visual quality. This study evaluated the repeatability of acuity (Bailey-Lovie [BL] and HOTV) in subjects with and without Down syndrome. METHODS: High-contrast VA was measured in both eyes of 30 subjects with Down syndrome (mean, 30 years; range, 18 to 50 years) and 24 control subjects without Down syndrome (mean, 29 years; range, 18 to 50 years). In the Down syndrome group, 23 subjects performed BL, and 7 subjects performed HOTV. All control subjects performed both BL and HOTV, but for HOTV analysis, only seven age-matched control subjects were included. For each eye, subjects performed VA three times on different charts (computer controlled, single-line display) until five total letters were missed on each chart. A repeated-measure ANOVA was used to compare the acuity measures between groups. RESULTS: The average logMAR VA for subjects with Down syndrome was approximately six lines worse than the control subjects (BL: Down syndrome = right eye: 0.51 ± 0.16, left eye: 0.53 ± 0.18; control = right eye: -0.06 ± 0.06, left eye: -0.06 ± 0.08, P < .0001; HOTV: Down syndrome = right eye: 0.47 ± 0.19, left eye: 0.46 ± 0.16; control: right eye = -0.11 ± 0.09, left eye: -0.07 ± 0.07, P < .001). Bailey-Lovie VA repeatability (1.96 * Sw * √2) was 0.13 logMAR (6.5 letters) for Down syndrome and 0.09 logMAR (4.5 letters) for control subjects. HOTV VA repeatability was 0.16 logMAR (eight letters) for both Down syndrome and control subjects. CONCLUSIONS: Despite poorer acuity in individuals with Down syndrome, repeatability of VA measurements was comparable to control subjects for both BL and HOTV techniques.

Impact of Cognitive Demand during Sustained Near Tasks in Children and Adults.

SIGNIFICANCE: These results demonstrate that accommodation in children is more accurate and less variable when performing a sustained near task with increased cognitive demand. In addition, children with increased uncorrected hyperopia have less stable accommodative responses, which may have visual implications during sustained near tasks. PURPOSE: This study investigated accommodative accuracy (lag) and variability during sustained viewing for passive and active tasks in children and adults with emmetropia and uncorrected hyperopia. METHODS: Lag and variability (root mean square [RMS] and low-frequency component) were measured in 54 children aged 3 to younger than 10 years with mean spherical equivalent of +1.31 ± 1.05 diopters (D) (range, -0.37 to +4.58 D) and 8 adults aged 22 to 32 years with mean spherical equivalent +0.65 ± 0.62 D (range, -0.13 to +1.15 D). Subjects viewed 20/50 stimuli at 33 cm during both a 10-minute passive and active task. Group 1 (<6 years or nonreaders) viewed shapes; group 2 (≥6 years and reading) and adults read passages. RESULTS: Groups 1 and 2 had larger lags, RMS, and low-frequency component for passive versus active tasks (P < .001). Lag and RMS did not differ between tasks in adults (P > .05), but low-frequency component was larger during passive viewing (P = .04). Group 1 had significantly higher RMS and low-frequency component than group 2 and the adults in the passive condition had greater low-frequency component in the active condition. In children, hyperopia was independently associated with RMS and low-frequency component under passive (RMS 95% confidence interval [CI], 0.04 to 0.15; low-frequency component 95% CI, 0.00011 to 0.00065) and active (RMS 95% CI, 0.001 to 0.06; 95% CI, 0.000014 to 0.00023) viewing. CONCLUSIONS: Accommodation is more accurate and less variable when children are engaged in the task. Children also have more variable accommodation than adults. In addition, children with greater hyperopia have more variable accommodation during sustained near tasks.

Objective measurement of spectacle wear with a temperature sensor data logger.

PURPOSE: This study seeks to establish the utility of the SmartButton Data Logger (www.acrsystems.com) to monitor spectacle wear for research and clinical applications. METHODS: Fifty adults wore a thermosensor on their spectacles for 2 weeks for each of two mount types while keeping wear-time logs. Temperatures during reported spectacle wear (ON) were compared to temperatures during non-wear (OFF) with repeated measures analysis of variance (ANOVA). In addition, two strategies to approximate spectacle wear from temperature data were evaluated: (1) Filtering data based on temperature ranges to identify spectacle wear (either group mean ON temperature, or an individual's mean ON temperature), and (2) Separate examiners inspecting temperature against time plots to identify spectacle wear. The success of these methods to approximate wear time was evaluated by per cent error with respect to subject reported wear time. RESULTS: Group mean ON (31.8 [0.6]°Celsius [°C]) and OFF (24.7 [1.5]°C) temperatures differed significantly (F1,47  = 471.2, p < 0.001), but there was no difference in temperature between mounts (F1,47  = 1.9, p = 0.18). Median per cent error and first and third quartiles (Q1, Q3) of each technique used to approximate wear time were: group mean filtering = 8% (Q1 3%, Q3 18%), individual mean filtering = 7% (Q1 4%, Q3 19%), Examiner 1 = 6% (Q1 2%, Q3 14%), Examiner 2 = 7% (Q1 3%, Q3 12%). CONCLUSIONS: The SmartButton can monitor spectacle compliance in patients with all approximation methods evaluated providing less than 10% median per cent error in wear time.