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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Variability in Objective Refraction for Persons with Down Syndrome.

PURPOSE: Down syndrome (DS) is associated with ocular and cognitive sequelae, which both have the potential to influence clinical measures of refractive error. This study compares variability of autorefraction among subjects with and without DS. METHODS: Grand Seiko autorefraction was performed on 139 subjects with DS (age: 8-55, mean: 25 ± 9 yrs) and 138 controls (age: 7-59, mean: 25 ± 10 yrs). Subjects with three refraction measures per eye (DS: 113, control: 136) were included for analysis. Each refraction was converted to power vector notation (M, J0, J45) and a difference in each component (ΔM, ΔJ0, ΔJ45) was calculated for each refraction pairing. From these quantities, average dioptric strength ((Equation is included in full-text article.): square root of the sum of the squares of M, J0, and J45) and average dioptric difference ((Equation is included in full-text article.): square root of the sum of the squares of ΔM, ΔJ0, and ΔJ45) were calculated. RESULTS: The DS group exhibited a greater median (Equation is included in full-text article.)(1Q: 1.38D M: 2.38D 3Q: 3.41D) than control eyes (1Q: 0.47D M: 0.96D 3Q: 2.75D) (P < .001). Likewise, the DS group exhibited a greater median (Equation is included in full-text article.)in refraction (1Q: 0.27D M: 0.42D 3Q: 0.78D) than control eyes (1Q: 0.11D M: 0.15D 3Q: 0.23D) (P < .001) with 97.1% of control eyes exhibiting (Equation is included in full-text article.)≤0.50D, compared to 59.3% of DS eyes. An effect of (Equation is included in full-text article.)on (Equation is included in full-text article.)was not detected (P = .3009) nor was a significant interaction between (Equation is included in full-text article.)and group detected (P = .49). CONCLUSIONS: In the current study, comparing three autorefraction readings, median total dioptric difference with autorefraction in DS was 2.8 times the levels observed in controls, indicating greater potential uncertainty in objective measures of refraction for this population. The analysis demonstrates that J45 is highly contributory to the observed variability.

Simulated Keratometry Repeatability in Subjects with and without Down Syndrome.

PURPOSE: To assess the repeatability of simulated keratometry measures obtained with Zeiss Atlas topography for subjects with and without Down syndrome (DS). METHODS: Corneal topography was attempted on 140 subjects with DS and 138 controls (aged 7-59 years). Subjects who had at least three measures in each eye were included in analysis (DS: n = 140 eyes (70 subjects) and controls: n = 264 eyes (132 subjects)). For each measurement, the steep corneal power (K), corneal astigmatism, flat K orientation, power vector representation of astigmatism (J0, J45), and astigmatic dioptric difference were determined for each measurement (collectively termed keratometry values here). For flat K orientation comparisons, only eyes with >0.50 DC of astigmatism were included (DS: n = 131 eyes (68 subjects) and control: n = 217 eyes (119 subjects)). Repeatability was assessed using (1) group mean variability (average standard deviation (SD) across subjects), (2) coefficient of repeatability (COR), (3) coefficient of variation (COV), and (4) intraclass correlation coefficient (ICC). RESULTS: The keratometry values showed good repeatability as evidenced by low group mean variability for DS versus control eyes (≤0.26D vs. ≤0.09D for all dioptric values; 4.51° vs. 3.16° for flat K orientation); however, the group mean variability was significantly higher in DS eyes than control eyes for all parameters (p ≤ 0.03). On average, group mean variability was 2.5 times greater in the DS eyes compared to control eyes across the keratometry values. Other metrics of repeatability also indicated good repeatability for both populations for each keratometry value, although repeatability was always better in the control eyes. CONCLUSIONS: DS eyes showed more variability (on average: 2.5×) compared to controls for all keratometry values. Although differences were statistically significant, on average 91% of DS eyes had variability ≤0.50D for steep K and astigmatism, and 75% of DS eyes had variability ≤5 degrees for flat K orientation.

A sloped piecemeal Gaussian model for characterising foveal pit shape.

PURPOSE: High-quality optical coherence tomography (OCT) macular scans make it possible to distinguish a range of normal and diseased states by characterising foveal pit shape. Existing mathematical models lack the flexibility to capture all known pit variations and thus characterise the pit with limited accuracy. This study aimed to develop a new model that provides a more robust characterisation of individual foveal pit variations. METHODS: A Sloped Piecemeal Gaussian (SPG) model, consisting of a linear combination of a tilted line and a piecemeal Gaussian function (two halves of a Gaussian connected by a separate straight line), was developed to fit retinal thickness data with the flexibility to characterise different degrees of pit asymmetry and pit bottom flatness. It fitted the raw pit data between the two rims of the fovea to improve accuracy. The model was tested on 3488 macular scans from both eyes of 581 young adults (376 myopes and 206 non-myopes, mean (S.D.) age 21.9 (1.4) years). Estimates for retinal thickness, wall height and slope, pit depth and width were derived from the best-fitting model curve. Ten variations of Gaussian and Difference of Gaussian models were fitted to the same scans and compared with the SPG model for goodness of fit (by Root mean square error, RMSE), model complexity (by the Bayesian Information Criteria) and model fidelity. RESULTS: The SPG model produced excellent goodness of fit (mean RMSE = 4.25 and 3.89 µm; 95% CI: 4.20, 4.30 and 3.86, 3.93 for fitting horizontal and vertical profiles respectively). The SPG model showed pit asymmetry, with average nasal walls 17.6 (11.6) µm higher and 0.96 (0.61)° steeper than temporal walls and average superior walls 7.0 (12.2) µm higher and 0.41 (0.65)° steeper than the inferior walls. The SPG model also revealed a continuum of human foveal shapes, from round bottoms to extended flat bottoms (up to 563 µm). 49.1% of foveal profiles were best fitted with a flat bottom >30 µm wide. Compared with the other tested models, the SPG was the preferred model overall based on the Bayesian Information Criteria. CONCLUSIONS: The SPG is a new parsimonious mathematical model that improves upon other models by accounting for wall asymmetry and flat pit bottoms, providing an excellent fit and more faithful characterisation of typical foveal pit shapes and their known variations. This new model may be helpful in distinguishing normal foveal shape variations by refractive status as well by other characteristics such as sex, ethnicity and age.

Cluster randomized controlled trial protocol: addressing reproductive coercion in health settings (ARCHES).

BACKGROUND: Women ages 16-29 utilizing family planning clinics for medical services experience higher rates of intimate partner violence (IPV) and reproductive coercion (RC) than their same-age peers, increasing risk for unintended pregnancy and related poor reproductive health outcomes. Brief interventions integrated into routine family planning care have shown promise in reducing risk for RC, but longer-term intervention effects on partner violence victimization, RC, and unintended pregnancy have not been examined. METHODS/DESIGN: The 'Addressing Reproductive Coercion in Health Settings (ARCHES)' Intervention Study is a cluster randomized controlled trial evaluating the effectiveness of a brief, clinician-delivered universal education and counseling intervention to reduce IPV, RC and unintended pregnancy compared to standard-of-care in family planning clinic settings. The ARCHES intervention was refined based on formative research. Twenty five family planning clinics were randomized (in 17 clusters) to either a three hour training for all family planning clinic staff on how to deliver the ARCHES intervention or to a standard-of-care control condition. All women ages 16-29 seeking care in these family planning clinics were eligible to participate. Consenting clients use laptop computers to answer survey questions immediately prior to their clinic visit, a brief exit survey immediately after the clinic visit, a first follow up survey 12-20 weeks after the baseline visit (T2), and a final survey 12 months after the baseline (T3). Medical record chart review provides additional data about IPV and RC assessment and disclosure, sexual and reproductive health diagnoses, and health care utilization. Of 4009 women approached and determined to be eligible based on age (16-29 years old), 3687 (92 % participation) completed the baseline survey and were included in the sample. DISCUSSION: The ARCHES Intervention Study is a community-partnered study designed to provide arigorous assessment of the short (3-4 months) and long-term (12 months) effects of a brief, clinician-delivered universal education and counseling intervention to reduce IPC, RC and unintended pregnancy in family planning clinic settings. The trial features a cluster randomized controlled trial design, a comprehensive data collection schedule and a large sample size with excellent retention. TRIAL REGISTRATION: ClinicialTrials.gov NCT01459458. Registered 10 October 2011.

Accommodative Gain in Relation to Perceived Target Clarity.

PURPOSE: The purpose of this study is to determine the relationship between target clarity and the magnitude of accommodative lag using the metric accommodative gain (AG). METHODS: Monocular accommodative responses were measured with Grand Seiko autorefraction using both proximal and minus lens techniques in 139 subjects aged 5 to 35 years. Subjects viewed a 1.5-mm letter at 13 discrete distances (range, 40 to 3.33 cm) for the proximal technique and fixed at 33 cm through minus lenses of increasing power for the lens technique. Subjects were instructed to keep the target clear and report when it blurred. The AG was calculated (accommodative response/accommodative demand) for the four greatest consecutive demands perceived clear (termed conditions 1 to 4) and the first demand perceived blurry (termed condition 5). RESULTS: Multivariate planned contrast, including age as a predictor, revealed that mean AG was significantly larger when the target was clear (range, 0.71 to 0.77 for conditions 1 to 4 across techniques) versus blurry (0.59 and 0.68 for condition 5 across techniques) (p < 0.001 for proximal and p < 0.036 for lens). Age was only a contributing factor for the proximal technique, with the youngest subjects having the largest decrease in AG when the target changed from clear to blurry (p = 0.017). CONCLUSIONS: These data suggest that across age and technique, the AG is relatively constant when the target is perceived clear but drops below approximately 70%, on average, once the target is perceived as blurry for subjects aged 5 to 35 years. The AG may be a useful metric to compare accommodative responses across a range of demands and to identify accommodative responses that may not be sufficient to perceive a clear target.

Comparison of Whole Eye versus First-Surface Astigmatism in Down Syndrome.

PURPOSE: Subjects with Down syndrome have structural differences in the cornea and lens, as compared with the general population. This study investigates objectively measured refractive and corneal astigmatism, as well as calculated internal astigmatism in subjects with and without Down syndrome. METHODS: Refractive (Grand Seiko autorefraction) and anterior corneal astigmatism (difference between steep and flat keratometry obtained with Zeiss Atlas corneal topography) were measured in 128 subjects with Down syndrome (mean [±SD] age, 24.8 [±8.7] years) and 137 control subjects without Down syndrome (mean [±SD] age, 24.9 [±9.9] years), with one eye randomly selected for analysis per subject. Refractive astigmatism and corneal astigmatism were converted to vector notation (J0, J45) to calculate internal astigmatism (Refractive - Corneal) and then converted back to minus cylinder form. RESULTS: Mean [±SD] refractive astigmatism was significantly greater in subjects with Down syndrome than in control subjects (-1.94 [±1.30] DC vs. -0.66 [±0.60] DC, t = -10.16, p < 0.001), as were mean corneal astigmatism (1.70 [±1.04] DC vs. 1.02 [±0.63] DC, t = 6.38, p < 0.001) and mean internal astigmatism (-1.07 [±0.68] DC vs. -0.77 [±0.41] DC, t = -4.21, p < 0.001). A positive linear correlation between corneal and refractive astigmatism was observed for both study populations for both the J0 and J45 vectors (p < 0.001 for all comparisons; R(2) range, 0.31 to 0.74). The distributions of astigmatism orientation differed significantly between the two study populations for comparisons of corneal and calculated internal astigmatism (χ(2), p < 0.007), but not refractive astigmatism (p = 0.46). CONCLUSIONS: This study demonstrates that corneal astigmatism is predictive of overall refractive astigmatism in subjects with Down syndrome, as it is in the general population. The greater magnitudes of astigmatism and wider variation of astigmatism orientation in subjects with Down syndrome for refractive, corneal, and calculated internal astigmatism are likely attributable to previously reported differences in the structure of the cornea and internal optical components of the eye from that of the general population.

Subjective versus objective accommodative amplitude: preschool to presbyopia.

PURPOSE: This study compared subjective and objective accommodative amplitudes to characterize changes from preschool to presbyopia. METHODS: Monocular accommodative amplitude was measured with three techniques in random order (subjective push-up, objective minus lens stimulated, and objective proximal stimulated) on 236 subjects aged 3 to 64 years using a 1.5-mm letter. Subjective push-up amplitudes were the dioptric distance at which the target first blurred along a near-point rod. Objective minus lens stimulated amplitudes were the greatest accommodative response obtained by Grand Seiko autorefraction as subjects viewed the stimulus at 33 cm through increasing minus lens powers. Objective proximal stimulated amplitudes were the greatest accommodative response obtained by Grand Seiko autorefraction as subjects viewed the stimulus at increasing proximity from 40 cm up to 3.33 cm. RESULTS: In comparison with subjective push-up amplitudes, objective amplitudes were lower at all ages, with the most dramatic difference occurring in the 3- to 5-year group (subjective push-up, 16.00 ± 4.98 diopters [D] vs. objective proximal stimulated, 7.94 ± 2.37 D, and objective lens stimulated, 6.20 ± 1.99 D). Objective proximal and lens stimulated amplitudes were largest in the 6- to 10-year group (8.81 ± 1.24 D and 8.05 ± 1.82 D, respectively) and gradually decreased until the fourth decade of life when a rapid decline to presbyopia occurred. There was a significant linear relationship between objective techniques (y = 0.74 + 0.96x, R2 = 0.85, p < 0.001) with greater amplitudes measured for the proximal stimulated technique (mean difference, 0.55 D). CONCLUSIONS: Objective measurements of accommodation demonstrate that accommodative amplitude is substantially less than that measured by the subjective push-up technique, particularly in young children. These findings have important clinical implications for the management of uncorrected hyperopia.

Training students with patient actors improves communication: a pilot study.

PURPOSE: Effective patient communication is correlated with better health outcomes and patient satisfaction, but is challenging to train, particularly with difficult clinical scenarios such as loss of sight. In this pilot study, we evaluated the use of simulated patient encounters with actors to train optometric students. METHODS: Students were recorded during encounters with actors and assigned to an enrichment group performing five interactions with instructor feedback (n = 6) or a no-enrichment group performing two interactions without feedback (n = 4). Student performance on first and last encounters was scored with (1) subjective rating of performance change using a visual analog scale (anchors: much worse/much better), (2) yes/no response: Would you recommend this doctor to a friend/relative?, and (3) average score on questions from the American Board of Internal Medicine (ABIM) assessment of doctor communication skills. Three clinical instructors, masked to student group assignments and the order of patient encounters they viewed, provided scores in addition to self-evaluation by students and patient-actors. RESULTS: Using the visual analog scale, students who received enrichment were rated more improved than the no-enrichment group by masked examiners (+18 vs. -11% p = 0.04) and self-evaluation (+79 vs. +27% p = 0.009), but not by actors (+31 vs. +43%). The proportion of students recommended significantly increased following enrichment for masked examiners (61% vs. 94%; p < 0.001), but not actors (100 vs. 83%). Average ABIM assessment scores were not significantly different by any rating group: masked instructors, actors, or self-ratings. CONCLUSIONS: The findings of this study suggest five simulated patient encounters with feedback result in measurable improvement in student-patient communication skills as rated by masked examiners.