Therapeutic non-ectasia applications of cornea cross-linking.

Corneal cross-linking is a photopolymerization technique traditionally used to strengthen corneal tissue. Corneal cross-linking utilizes riboflavin (vitamin B2) as a photosensitizer and ultraviolet-A light (UVA) to create strong covalent bonds within the corneal stroma, increasing tissue stiffness. Multiple studies have demonstrated corneal cross-linking's effectiveness in treating corneal ectasia, a progressive, degenerative, and non-inflammatory thinning disorder, as quantified by key tomographic, refractive, and visual parameters. Since its introduction two decades ago, corneal cross-linking has surpassed its original application in halting corneal ectatic disease and its application has expanded into several other areas. Corneal cross-linking also possesses antibacterial, antienzymolytic and antioedematous properties, and has since become a tool in treating microbial keratitis, correcting refractive error, preventing iatrogenic ectasia, stabilising bullous keratopathy and controlling post keratoplasty ametropia. This review provides an overview of the current evidence base for the therapeutic non-ectasia applications of cornea cross-linking and looks at future developments in the field.

Factorial Validity of the Theory of Mind Inventory-2 in Typically Developing Children.

The Theory of Mind Inventory-2 (ToMI-2) is a promising measure for assessing theory of mind (ToM) and social-related functions. However, limited evidence on its factorial validity hampers score interpretation. To examine the factorial validity, confirmatory factor analysis for two currently-available structures was performed in 420 typically developing children aged three to seven years. One, the development-based structure, contains three stages of ToM development: the early, basic, and advanced ToM stages. The other, the social-related structure, comprises three social-related ToM functions: emotion recognition, mental state term comprehension, and pragmatics. The results showed that these structures and the unidimensionality of each domain were not supported even after modifications. Thus, further revisions and examinations of the underlying structures of the ToMI-2 are needed.

Test-retest reliability and convergent validity of the test of nonverbal intelligence-fourth edition in patients with schizophrenia.

BACKGROUND: Fluid intelligence deficits affect executive functioning and social behaviors in patients with schizophrenia. To help clinicians manage fluid intelligence deficits, a psychometrically sound measure is needed. The purposes of this study were to examine the test-retest reliability and convergent validity of the Test of Nonverbal Intelligence-Fourth Edition (TONI-4) assessing fluid intelligence in patients with schizophrenia. METHODS: A total of 103 patients with stable condition were assessed with the TONI-4 twice with a 4-week interval to examine the test-retest reliability. We further used the Montreal Cognitive Assessment (MoCA) and the Tablet-Based Symbol Digit Modalities Test (T-SDMT) to examine the convergent validity of the TONI-4. RESULTS: The intra-class correlation coefficient was 0.73 for the TONI-4. The percentages of standard error of measurement and minimal detectable change for the TONI-4 were 5.1 and 14.2%, respectively. The practice effect of the TONI-4 was small (Cohen's d = - 0.03). Convergent validity showed small to moderate significant correlations between the TONI-4 and the MoCA as well as the T-SDMT (r = 0.35, p = .011 with the T-SDMT and r = 0.61, p < .001 with the MoCA). The results demonstrated that the TONI-4 had good test-retest reliability, limited random measurement error, and a trivial practice effect. The convergent validity of the TONI-4 was good. CONCLUSIONS: These findings indicate that the TONI-4 has potential to be a reliable and valid assessment of fluid intelligence in patients with schizophrenia.

Psychometric Properties and Efficiency of the Computerized Adaptive Testing System for Measuring Self-Care Performance in Taiwanese Children With Developmental Disabilities.

OBJECTIVE: To investigate the psychometric properties and efficiency of the computerized adaptive testing system for measuring self-care performance (CAT-SC). The psychometric properties included intrarater and interrater reliabilities, concurrent validity, minimal detectable change, minimal important difference, and responsiveness. DESIGN: Criterion standard study. SETTING: A teaching hospital. PARTICIPANTS: A convenience sample of 60 caregivers of children with developmental disabilities was recruited at the initial assessment, and 95% of the children (N=57) were followed-up at 3 and 6 months. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The CAT-SC and the Pediatric Evaluation of Disability Inventory Chinese version were used at the initial assessment. We assessed the CAT-SC and asked caregivers to rate children's changes in self-care performance with a separate question rated on a 15-point Likert-type scale at the 3- and 6-month follow-ups. RESULTS: The CAT-SC had excellent intrarater and interrater reliabilities (intraclass coefficient=0.99 and 0.92, respectively), high concurrent validity with the Pediatric Evaluation of Disability Inventory (r=0.91-0.92), and trivial to small responsiveness at 3- and 6-month follow-ups (effect size=0.02 and 0.12, standardized response mean=0.08 and 0.33). The minimal detectable change of intrarater reliabilities and the minimal important difference at the first follow-up were 0.22 and 0.17 logits, respectively. The administration time of the CAT-SC was about 5 minutes. CONCLUSIONS: The results of our study validated the sound psychometric properties and good efficiency of the CAT-SC. Moreover, the values of the minimal detectable change and minimal smallest change can be used as a reference for clinicians and caregivers to interpret children's progress.

Differences Between the Childhood Autism Rating Scale and the Social Responsiveness Scale in Assessing Symptoms of Children with Autistic Spectrum Disorder.

This study aimed to compare symptoms of autism spectrum disorder using the Childhood Autism Rating Scale (CARS) and the Social Responsiveness Scale (SRS™-2) and to investigate their influencing factors. The diagnostic agreement was 92.7%, but with a fair Kappa value (0.247). Children's verbal comprehension was related to the CARS scores, and no variables were related to the SRS™-2 scores. Generally, significant small correlations were found between the two measures in children with normal or borderline to below average verbal comprehension (rs = 0.32 ~ 0.49, p < .005), but not in those with impaired verbal comprehension. The CARS and the SRS™-2 may contain different explicit behaviors and collect different perspectives (i.e., those of caregivers and professionals). Therefore, they appear to complement each other.

IQ discrepancy differentiates levels of fine motor skills and their relationship in children with autism spectrum disorders.

PURPOSE: We investigated 1) the impact of differences in intelligence quotient discrepancy (IQD) on motor skills of preschool-aged children with autism spectrum disorders (ASD); 2) the relationships between IQD and motor skills in preschool-aged children with ASD. METHODS: A total of 127 ASD preschool-aged children were divided into three groups according to the size of the IQD: IQD within 1 standard deviation (1SD; EVENIQ; n=81), discrepantly higher verbal intelligence quotient (VIQ; n=22; VIQ>performance intelligence quotient [PIQ] above 1SD [≥15 points]), and discrepantly higher PIQ (n=24; PIQ>VIQ above 1SD [≥15 points]). Children's IQD and motor skills were determined with the Wechsler Preschool and Primary Scale of Intelligence™ - Fourth Edition and the motor subtests of the Comprehensive Developmental Inventory for Infants and Toddlers (CDIIT), respectively. RESULTS: One-way analysis of variance revealed significant group differences for the fine motor domain of the CDIIT and the visual-motor coordination subtest (F=3.37-4.38, p<0.05). Children with discrepantly higher PIQ were associated with better fine motor skills than were children with even IQD and those with discrepantly higher VIQ, and vice versa. IQD (PIQ - VIQ) had significant positive correlations with the fine motor domain and fine motor subtests of the CDIIT (r=0.18-0.29, p<0.05). CONCLUSION: The IQD can identify different levels of fine motor skills in preschool-aged children with ASD. This study suggests important implications for clinicians, therapists, and researchers: discrepantly higher PIQ could be related to better visual-motor coordination, and discrepantly higher VIQ could be related to poor visual-motor coordination. Furthermore, the results support that when therapists are working with preschool-aged children with ASD who are developing fine motor skills or undertaking fine motor tasks related to visual-motor coordination, they may need to pay attention to the children's IQD.

Retinopathy of prematurity: the high cost of screening regional and remote infants.

IMPORTANCE: Demand for retinopathy of prematurity (ROP) screening is increasing for infants born at rural and regional hospitals where the service is not generally available. The health system cost for screening regional/remote infants has not been reported. BACKGROUND: The objective of this study is to evaluate the cost of ROP screening at a large centralized tertiary neonatal service for infants from regional/rural hospitals. DESIGN: This is a retrospective study to establish the cost of transferring regional/rural infants to the Royal Brisbane and Women's Hospital for ROP screening over a 28-month period. PARTICIPANTS: A total of 131 infants were included in this study. METHODS: Individual infant costs were calculated from analysis of clinical and administrative records. MAIN OUTCOME MEASURES: Economic cost of ROP screening for all transfers from regional/rural hospitals to Royal Brisbane and Women's Hospital. RESULTS: The average economic cost of ROP screening for this cohort was AUD$5110 per infant screened and the total cost was AUD$669 413. The average cost per infant screened was highest for infants from a regional centre with a population of 75 000 (AUD$14 856 per child), which was also geographically furthest from Brisbane. No infant in this cohort transferred from a regional nursery reached criteria for intervention for ROP by standard guidelines. CONCLUSIONS AND RELEVANCE: Health system costs for ROP screening of remote infants at a centralized hospital are high. Alternative strategies using telemedicine can now be compared with centralized screening.

Vision screening at two years does not reduce the prevalence of reduced vision at four and a half years of age.

BACKGROUND: There is currently insufficient evidence to recommend vision screening for children < 36 months of age. This study assessed the effect of comprehensive vision screening, as well as the sensitivity of age-appropriate vision tests, at two years of age on habitual visual acuity at 4.5 years of age. METHODS: Children born at risk of neonatal hypoglycaemia (n = 477) underwent vision assessment at 54 ± 2 months of age including measurement of monocular and binocular habitual visual acuity, assessment of binocularity and stereopsis. Of these children, 355 (74.4 per cent) had also received vision screening at two years of age (mean age = 24± 1 months), while 122 were not screened. RESULTS: Eighty (16.8 per cent) children were classified as having reduced vision at 4.5 years of age, but the prevalence of reduced vision did not differ between children who had previously been screened at two years of age and those who had not (15.5 per cent versus 20.5 per cent, p = 0.153). However, children with reduced vision at 4.5 years of age were more likely to have had visual abnormalities requiring referral detected at two years of age (p = 0.02). Visual acuity and mean spherical equivalent autorefraction measurements were also worse (higher values) in two-year-old children who were later classified with reduced habitual visual acuity (p = 0.031 and p = 0.001, respectively). Nevertheless, unaided binocular visual acuity, non-cycloplegic refractive error, and stereopsis at two years all showed poor sensitivity and specificity for predicting visual outcomes at 4.5 years of age. CONCLUSION: Our findings do not support the adoption of early vision screening in children as current vision tests suitable for use with two-year-old children have poor sensitivity for predicting mild-moderate habitual vision impairment at 4.5 years of age.

Global motion perception is associated with motor function in 2-year-old children.

The dorsal visual processing stream that includes V1, motion sensitive area V5 and the posterior parietal lobe, supports visually guided motor function. Two recent studies have reported associations between global motion perception, a behavioural measure of processing in V5, and motor function in pre-school and school aged children. This indicates a relationship between visual and motor development and also supports the use of global motion perception to assess overall dorsal stream function in studies of human neurodevelopment. We investigated whether associations between vision and motor function were present at 2 years of age, a substantially earlier stage of development. The Bayley III test of Infant and Toddler Development and measures of vision including visual acuity (Cardiff Acuity Cards), stereopsis (Lang stereotest) and global motion perception were attempted in 404 2-year-old children (±4 weeks). Global motion perception (quantified as a motion coherence threshold) was assessed by observing optokinetic nystagmus in response to random dot kinematograms of varying coherence. Linear regression revealed that global motion perception was modestly, but statistically significantly associated with Bayley III composite motor (r2=0.06, P<0.001, n=375) and gross motor scores (r2=0.06, p<0.001, n=375). The associations remained significant when language score was included in the regression model. In addition, when language score was included in the model, stereopsis was significantly associated with composite motor and fine motor scores, but unaided visual acuity was not statistically significantly associated with any of the motor scores. These results demonstrate that global motion perception and binocular vision are associated with motor function at an early stage of development. Global motion perception can be used as a partial measure of dorsal stream function from early childhood.

Intelligence quotient discrepancy indicates levels of motor competence in preschool children at risk for developmental delays.

PURPOSE: This study aimed to establish 1) whether a group difference exists in the motor competence of preschool children at risk for developmental delays with intelligence quotient discrepancy (IQD; refers to difference between verbal intelligence quotient [VIQ] and performance intelligence quotient [PIQ]) and 2) whether an association exists between IQD and motor competence. METHODS: Children's motor competence and IQD were determined with the motor subtests of the Comprehensive Developmental Inventory for Infants and Toddlers and Wechsler Preschool and Primary Scale of Intelligence™ - Fourth Edition. A total of 291 children were included in three groups: NON-IQD (n=213; IQD within 1 standard deviation [SD]), VIQ>PIQ (n=39; VIQ>PIQ greater than 1 SD), and PIQ>VIQ (n=39; PIQ>VIQ greater than 1 SD). RESULTS: The results of one-way analysis of variance indicated significant differences among the subgroups for the "Gross and fine motor" subdomains of the Comprehensive Developmental Inventory for Infants and Toddlers, especially on the subtests of "body-movement coordination" (F=3.87, P<0.05) and "visual-motor coordination" (F=6.90, P<0.05). Motor competence was significantly worse in the VIQ>PIQ group than in the NON and PIQ>VIQ groups. Significant negative correlations between IQD and most of the motor subtests (r=0.31-0.46, P<0.01) were found only in the VIQ>PIQ group. CONCLUSION: This study demonstrates that 1) IQD indicates the level of motor competence in preschoolers at risk for developmental delays and 2) IQD is negatively associated with motor competence in preschoolers with significant VIQ>PIQ discrepancy. The first finding was that preschoolers with VIQ>PIQ discrepancy greater than 1 SD performed significantly worse on motor competence than did preschoolers without significant IQD and preschoolers with PIQ>VIQ discrepancy greater than 1 SD. However, preschoolers with significant PIQ>VIQ discrepancy performed better on motor competence than did preschoolers without significant IQD, though the difference was not statistically significant. The second finding was that preschoolers with larger VIQ>PIQ discrepancy had worse motor competence in visual-motor integration and body-movement coordination. Professionals should pay attention to the motor development of children with VIQ>PIQ discrepancy and evaluate children's IQD along with their motor competence.

Development of a Tablet-based symbol digit modalities test for reliably assessing information processing speed in patients with stroke.

PURPOSE: To develop a Tablet-based Symbol Digit Modalities Test (T-SDMT) and to examine the test-retest reliability and concurrent validity of the T-SDMT in patients with stroke. METHODS: The study had two phases. In the first phase, six experts, nine college students and five outpatients participated in the development and testing of the T-SDMT. In the second phase, 52 outpatients were evaluated twice (2 weeks apart) with the T-SDMT and SDMT to examine the test-retest reliability and concurrent validity of the T-SDMT. RESULTS: The T-SDMT was developed via expert input and college student/patient feedback. Regarding test-retest reliability, the practise effects of the T-SDMT and SDMT were both trivial (d=0.12) but significant (p≦0.015). The improvement in the T-SDMT (4.7%) was smaller than that in the SDMT (5.6%). The minimal detectable changes (MDC%) of the T-SDMT and SDMT were 6.7 (22.8%) and 10.3 (32.8%), respectively. The T-SDMT and SDMT were highly correlated with each other at the two time points (Pearson's r=0.90-0.91). CONCLUSIONS: The T-SDMT demonstrated good concurrent validity with the SDMT. Because the T-SDMT had a smaller practise effect and less random measurement error (superior test-retest reliability), it is recommended over the SDMT for assessing information processing speed in patients with stroke. Implications for Rehabilitation The Symbol Digit Modalities Test (SDMT), a common measure of information processing speed, showed a substantial practise effect and considerable random measurement error in patients with stroke. The Tablet-based SDMT (T-SDMT) has been developed to reduce the practise effect and random measurement error of the SDMT in patients with stroke. The T-SDMT had smaller practise effect and random measurement error than the SDMT, which can provide more reliable assessments of information processing speed.

Outcome at 2 Years after Dextrose Gel Treatment for Neonatal Hypoglycemia: Follow-Up of a Randomized Trial.

OBJECTIVE: To determine neurodevelopmental outcome at 2 years' corrected age in children randomized to treatment with dextrose gel or placebo for hypoglycemia soon after birth (The Sugar Babies Study). STUDY DESIGN: This was a follow-up study of 184 children with hypoglycemia (<2.6 mM [47 mg/dL]) in the first 48 hours and randomized to either dextrose (90/118, 76%) or placebo gel (94/119, 79%). Assessments were performed at Kahikatea House, Hamilton, New Zealand, and included neurologic function and general health (pediatrician assessed), cognitive, language, behavior, and motor skills (Bayley Scales of Infant and Toddler Development, Third Edition), executive function (clinical assessment and Behaviour Rating Inventory of Executive Function-Preschool Edition), and vision (clinical examination and global motion perception). Coprimary outcomes were neurosensory impairment (cognitive, language or motor score below -1 SD or cerebral palsy or blind or deaf) and processing difficulty (executive function or global motion perception worse than 1.5 SD from the mean). Statistical tests were two sided with 5% significance level. RESULTS: Mean (± SD) birth weight was 3093 ± 803 g and mean gestation was 37.7 ± 1.6 weeks. Sixty-six children (36%) had neurosensory impairment (1 severe, 6 moderate, 59 mild) with similar rates in both groups (dextrose 38% vs placebo 34%, relative risk 1.11, 95% CI 0.75-1.63). Processing difficulty also was similar between groups (dextrose 10% vs placebo 18%, relative risk 0.52, 95% CI 0.23-1.15). CONCLUSIONS: Dextrose gel is safe for the treatment of neonatal hypoglycemia, but neurosensory impairment is common among these children. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN 12608000623392.

Neonatal Glycemia and Neurodevelopmental Outcomes at 2 Years.

BACKGROUND: Neonatal hypoglycemia is common and can cause neurologic impairment, but evidence supporting thresholds for intervention is limited. METHODS: We performed a prospective cohort study involving 528 neonates with a gestational age of at least 35 weeks who were considered to be at risk for hypoglycemia; all were treated to maintain a blood glucose concentration of at least 47 mg per deciliter (2.6 mmol per liter). We intermittently measured blood glucose for up to 7 days. We continuously monitored interstitial glucose concentrations, which were masked to clinical staff. Assessment at 2 years included Bayley Scales of Infant Development III and tests of executive and visual function. RESULTS: Of 614 children, 528 were eligible, and 404 (77% of eligible children) were assessed; 216 children (53%) had neonatal hypoglycemia (blood glucose concentration, <47 mg per deciliter). Hypoglycemia, when treated to maintain a blood glucose concentration of at least 47 mg per deciliter, was not associated with an increased risk of the primary outcomes of neurosensory impairment (risk ratio, 0.95; 95% confidence interval [CI], 0.75 to 1.20; P=0.67) and processing difficulty, defined as an executive-function score or motion coherence threshold that was more than 1.5 SD from the mean (risk ratio, 0.92; 95% CI, 0.56 to 1.51; P=0.74). Risks were not increased among children with unrecognized hypoglycemia (a low interstitial glucose concentration only). The lowest blood glucose concentration, number of hypoglycemic episodes and events, and negative interstitial increment (area above the interstitial glucose concentration curve and below 47 mg per deciliter) also did not predict the outcome. CONCLUSIONS: In this cohort, neonatal hypoglycemia was not associated with an adverse neurologic outcome when treatment was provided to maintain a blood glucose concentration of at least 47 mg per deciliter. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others.).

Exendin-4-loaded PLGA microspheres relieve cerebral ischemia/reperfusion injury and neurologic deficits through long-lasting bioactivity-mediated phosphorylated Akt/eNOS signaling in rats.

Glucagon-like peptide-1 (GLP-1) receptor activation in the brain provides neuroprotection. Exendin-4 (Ex-4), a GLP-1 analog, has seen limited clinical usage because of its short half-life. We developed long-lasting Ex-4-loaded poly(D,L-lactide-co-glycolide) microspheres (PEx-4) and explored its neuroprotective potential against cerebral ischemia in diabetic rats. Compared with Ex-4, PEx-4 in the gradually degraded microspheres sustained higher Ex-4 levels in the plasma and cerebrospinal fluid for at least 2 weeks and improved diabetes-induced glycemia after a single subcutaneous administration (20 µg/day). Ten minutes of bilateral carotid artery occlusion (CAO) combined with hemorrhage-induced hypotension (around 30 mm Hg) significantly decreased cerebral blood flow and microcirculation in male Wistar rats subjected to streptozotocin-induced diabetes. CAO increased cortical O2(-) levels by chemiluminescence amplification and prefrontal cortex edema by T2-weighted magnetic resonance imaging analysis. CAO significantly increased aquaporin 4 and glial fibrillary acidic protein expression and led to cognition deficits. CAO downregulated phosphorylated Akt/endothelial nitric oxide synthase (p-Akt/p-eNOS) signaling and enhanced nuclear factor (NF)-κBp65/intercellular adhesion molecule-1 (ICAM-1) expression, endoplasmic reticulum (ER) stress, and apoptosis in the cerebral cortex. PEx-4 was more effective than Ex-4 to improve CAO-induced oxidative injury and cognitive deficits. The neuroprotection provided by PEx-4 was through p-Akt/p-eNOS pathways, which suppressed CAO-enhanced NF-κB/ICAM-1 signaling, ER stress, and apoptosis.

A method for detecting optokinetic nystagmus based on the optic flow of the limbus.

Optokinetic nystagmus (OKN) is the sawtooth movement of the eye elicited when an observer views a repeated moving pattern. We present a method for identifying the presence and direction of OKN in recordings of the eye made using a standard off-the-shelf video-camera or webcam. Our approach uses vertical edge detection to determine the limbus/iris boundary, and we estimate the velocity of the edge using Lucas-Kanade optical flow. Heuristic rules are applied to identify saccadic velocity peaks from the resulting velocity signal. The normalized average of the resulting peaks is used to estimate the presence/direction of OKN. Our preliminary testing with six participants observing global motion stimuli with full or partial coherence yields an accuracy of 93% which compares favorably to the performance of an experienced human observer (98% accuracy). Additional tests using high contrast, square-wave gratings show that performance of the technique is consistent at stimulus speeds of 5 and 10deg/s and that OKN is not reported by the algorithm when participants view stationary stimuli.

Glucagon-like peptide-1 receptor agonist activation ameliorates venous thrombosis-induced arteriovenous fistula failure in chronic kidney disease.

High shear stress that develops in the arteriovenous fistula of chronic kidney diseases (CKD) may increase H2O2 and thromboxane A2 (TXA2) release, thereby exacerbating endothelial dysfunction, thrombosis, and neointimal hyperplasia. We investigated whether glucagon-like peptide-1 receptor agonist/exendin-4, a potentially cardiovascular protective agent, could improve TXA2-induced arteriovenous fistula injury in CKD. TXA2 administration to H2O2-exposed human umbilical vein endothelial cells increased apoptosis, senescence, and detachment; these phenotypes were associated with the downregulation of phosphorylated endothelial nitric oxide synthase/heme oxygenase-1 (eNOS/HO-1) signalling. Exendin-4 reduced H2O2/TXA2-induced endothelial injury via inhibition of apoptosis-related mechanisms and restoration of phosphorylated eNOS/HO-1 signalling. Male Wistar rats subjected to right common carotid artery-external jugular vein anastomosis were treated with exendin-4 via cervical implant osmotic pumps for 16-42 days. High shear stress induced by the arteriovenous fistula significantly increased venous haemodynamics, blood and tissue H2O2 and TXB2 levels, macrophage/monocyte infiltration, fibrosis, proliferation, and adhesion molecule-1 expression. Apoptosis was also increased due to NADPH oxidase gp91 activation and mitochondrial Bax translocation in the proximal end of the jugular vein of CKD rats. Exendin-4-treatment of rats with CKD led to the restoration of normal endothelial morphology and correction of arteriovenous fistula function. Exendin-4 treatment or thromboxane synthase gene deletion in CKD mice markedly reduced ADP-stimulated platelet adhesion to venous endothelium, and prevented venous occlusion in FeCl3-injured vessels by upregulation of HO-1. Together, these data reveal that the use of glucagon-like peptide-1 receptor agonists is an effective strategy for treatment of CKD-induced arteriovenous fistula failure.

Global motion perception in 2-year-old children: a method for psychophysical assessment and relationships with clinical measures of visual function.

PURPOSE: We developed and validated a technique for measuring global motion perception in 2-year-old children, and assessed the relationship between global motion perception and other measures of visual function. METHODS: Random dot kinematogram (RDK) stimuli were used to measure motion coherence thresholds in 366 children at risk of neurodevelopmental problems at 24 ± 1 months of age. RDKs of variable coherence were presented and eye movements were analyzed offline to grade the direction of the optokinetic reflex (OKR) for each trial. Motion coherence thresholds were calculated by fitting psychometric functions to the resulting datasets. Test-retest reliability was assessed in 15 children, and motion coherence thresholds were measured in a group of 10 adults using OKR and behavioral responses. Standard age-appropriate optometric tests also were performed. RESULTS: Motion coherence thresholds were measured successfully in 336 (91.8%) children using the OKR technique, but only 31 (8.5%) using behavioral responses. The mean threshold was 41.7 ± 13.5% for 2-year-old children and 3.3 ± 1.2% for adults. Within-assessor reliability and test-retest reliability were high in children. Children's motion coherence thresholds were significantly correlated with stereoacuity (LANG I & II test, ρ = 0.29, P < 0.001; Frisby, ρ = 0.17, P = 0.022), but not with binocular visual acuity (ρ = 0.11, P = 0.07). In adults OKR and behavioral motion coherence thresholds were highly correlated (intraclass correlation = 0.81, P = 0.001). CONCLUSIONS: Global motion perception can be measured in 2-year-old children using the OKR. This technique is reliable and data from adults suggest that motion coherence thresholds based on the OKR are related to motion perception. Global motion perception was related to stereoacuity in children.

A test case: does the availability of visual feedback impact grip strength scores when using a digital dynamometer?

UNLABELLED: A cross-sectional, quantitative study of clinical measurement utility. New technological advances can challenge the efficacy of even the most widely accepted and respected tests. For example, grip strength instruments offer digital or computerized displays, precision scoring, and varied interfaces that differ from traditional Jamar™ dynamometers (Lafayette, IN). This test case explores how the opportunity to view grip strength scores during testing can influence outcomes. One hundred forty-six healthy subjects, aged 18-24 years, were tested for grip strength under visual feedback and no visual feedback conditions, using the JTech Grip Dynamometer (Salt Lake City, UT). Participants achieved a small, yet statistically significant, 1.74 lb stronger grip score with visual feedback (p<0.002). The order of grip testing conditions yielded no statistically significant differences (p=0.559). These findings suggest the need to consider how new features, unavailable with the analog Jamar™ dynamometer and unaccounted for in existing clinical guidelines could potentially influence grip scores. LEVEL OF EVIDENCE: Not applicable.

Light exposure causes functional changes in the retina: increased photoreceptor cation channel permeability, photoreceptor apoptosis, and altered retinal metabolic function.

Light exposure induces retinal photoreceptor degeneration and retinal remodeling in both the normal rat retina and in animal models of retinal degeneration. Although cation entry is one of the triggers leading to apoptosis, it is unclear if this event occurs in isolation, or whether a number of pathways lead to photoreceptor apoptosis following light exposure. Following light exposure, we investigated the characteristics of cation entry, apoptotic markers [using terminal deoxynucleotidyl transferase (EC 2.7.7.31) dUTP nick-end labeling (TUNEL) labeling] and metabolic properties of retina from Sprague-Dawley (SD) rats and a rat model of retinitis pigmentosa [proline-23-histidine (P23H) rat]. Assessment of cation channel permeability using agmatine (AGB) labeling showed that excessive cation gating accompanied the series of anomalies that occur prior to photoreceptor loss. Increased AGB labeling in photoreceptors was seen in parallel with the appearance of apoptotic photoreceptors detected by TUNEL labeling with only a smaller proportion of cells colocalizing both markers. However, SD and P23H retinal photoreceptors differed in the amounts and colocalization of AGB gating and TUNEL labeling as a function of light exposure. Finally, reduced retinal lactate dehydrogenase levels were found in SD and P23H rat retinas after a 24-h light exposure period. Short-term (2 h) exposure of the P23H rat retina caused an increase in lactate dehydrogenase activity suggesting increased metabolic demand. These results suggest that energy availability may be exacerbated during the early stages of light exposure in susceptible retinas. Also, the concomitant observation of increased ion gating and TUNEL labeling suggest the existence of at least two possible mechanisms in light-damaged retinas in both SD and the P23H rat retina.

A Rasch analysis of the Frenchay Activities Index in patients with spinal cord injury.

STUDY DESIGN: A prospective interview study. OBJECTIVE: To determine whether items of the Frenchay Activities Index (FAI) measure Instrumental Activities of Daily Living (IADL), as a unidimensional construct, in patients with spinal cord injury (SCI). To examine whether the response categories of the FAI are useful in discerning the various ability levels of IADL. SUMMARY OF BACKGROUND DATA: No known IADL scale has been designed for SCI patients. The FAI, to our knowledge, has never been validated in patients with SCI. METHODS: A total of 233 persons with SCI participated in this study. The FAI was administered to the patients by interview at locations convenient for the participants. A Rasch analysis was used to examine the unidimensionality and appropriateness of the response categories of the FAI. RESULTS: All but 2 items ("going outside" and "reading books") of the FAI fitted the model's expectations. The results of Rasch analysis indicated that the response categories for the remaining 13 items of the FAI should be collapsed to create more suitable response categories (4 items, into dichotomies, and the remaining 9 items, into trichotomies). Thus, a revised 13-item FAI was formed by deleting the 2 misfitting items and collapsing the response categories of the items. CONCLUSIONS: This study demonstrated that the revised 13-item FAI assesses a single, unidimensional IADL for SCI patients living in the community. The revised FAI shows potential for assessment of IADL in SCI patients.