Astigmatism and early academic readiness in preschool children.

PURPOSE: This study investigated the relationship between uncorrected astigmatism and early academic readiness in at-risk preschool-aged children. METHODS: A vision screening and academic records review were performed on 122 three- to five-year-old children enrolled in the Philadelphia Head Start program. Vision screening results were related to two measures of early academic readiness, the teacher-reported Work Sampling System (WSS) and the parent-reported Ages and Stages Questionnaire (ASQ). Both measures assess multiple developmental and skill domains thought to be related to academic readiness. Children with astigmatism (defined as >|-0.25| in either eye) were compared with children who had no astigmatism. Associations between astigmatism and specific subscales of the WSS and ASQ were examined using parametric and nonparametric bivariate statistics and regression analyses controlling for age and spherical refractive error. RESULTS: Presence of astigmatism was negatively associated with multiple domains of academic readiness. Children with astigmatism had significantly lower mean scores on Personal and Social Development, Language and Literacy, and Physical Development domains of the WSS, and on Personal/Social, Communication, and Fine Motor domains of the ASQ. These differences between children with astigmatism and children with no astigmatism persisted after statistically adjusting for age and magnitude of spherical refractive error. Nonparametric tests corroborated these findings for the Language and Literacy and Physical Health and Development domains of the WSS and the Communication domain of the ASQ. CONCLUSIONS: The presence of astigmatism detected in a screening setting was associated with a pattern of reduced academic readiness in multiple developmental and educational domains among at-risk preschool-aged children. This study may help to establish the role of early vision screenings, comprehensive vision examinations, and the need for refractive correction to improve academic success in preschool children.

Aarskog syndrome: a case report and literature review.

BACKGROUND: Aarskog syndrome (facial-digital-genital syndrome) is an X-linked inherited disorder that causes multiple limb and genital abnormalities. Although ophthalmic manifestations are noted rarely, findings may include optic nerve hypoplasia, retinal vessel tortuosity, deficient ocular elevation, hyperopia, and anisometropia. CASE REPORT: An 8-year-old boy with Aarskog syndrome presented with complaints of letter reversals, letter additions, and an occasional "crooked" eye when he became frustrated or tired. He was currently enrolled in a special education program because of poor academics. The examination found anisometropic amblyopia, superior ophthalmoplegia, and high hyperopic astigmatism. Glasses were prescribed, and further binocular, accommodative and perceptual testing will be performed once adaptation has occurred. CONCLUSION: Knowledge of this rare condition can benefit the practitioner as well as the patient. An understanding of the associated conditions will aid and simplify the examination process. A search of the English-language literature is reported.

A comparision of short and long reading passages in symptomatic vs. asymptomatic subjects.

BACKGROUND: The visual system is necessary for reading. Understanding the mechanics of eye movements during reading can give insight into the reading process. The ReadAlyzer is an electronic recording system that measures eye movements while reading. Long passages on the ReadAlyzer of 800 words have recently been introduced as a tool to assess the efficiency of reading eye movements. Previously, short passages of 100 words have been used exclusively. This project was designed to determine if passage length influences the quality of reading eye movements; METHODS: Optometry students (N = 40) at Southern College of Optometry were separated into 2 equal groups (symptomatic vs. asymptomatic) based on the College of Optometrists in Vision Development Quality of Life questionnaire score. Each subject then performed two reading passage recordings with the ReadAlyzer: one short, one long. The order of the passages was alternated to reduce fatigue effects. Data were collected based on the ratio of fixations-to-regressions; RESULTS: A multivariate analysis of variance indicated that the difference between short and long paragraphs for the symptomatic and asymptomatic groups combined was significant (P = 0.001) but was not significant for the symptomatic group vs. the asymptomatic group ( P = 0. 651) . Post-hoc comparisons using estimated marginal means indicated for asymptomatic, short vs. long, P = .036 and for symptomatic, short vs. long, P = 0.008. Additionally, for short length, symptomatic vs. asymptomatic, P = 0.242 and for long length, symptomatic vs. asymptomatic, P = 0.176; CONCLUSION: This information indicates that both symptomatic and asymptomatic patients will have more difficulty on longer reading passages. This finding calls into question the use of shorter length reading tests to determine a diagnosis of ocular motor dysfunction and other visual efficiency problems.

Overnight closed-loop insulin delivery with model predictive control: assessment of hypoglycemia and hyperglycemia risk using simulation studies.

BACKGROUND: Hypoglycemia and hyperglycemia during closed-loop insulin delivery based on subcutaneous (SC) glucose sensing may arise due to (1) overdosing and underdosing of insulin by control algorithm and (2) difference between plasma glucose (PG) and sensor glucose, which may be transient (kinetics origin and sensor artifacts) or persistent (calibration error [CE]). Using in silico testing, we assessed hypoglycemia and hyperglycemia incidence during over-night closed loop. Additionally, a comparison was made against incidence observed experimentally during open-loop single-night in-clinic studies in young people with type 1 diabetes mellitus (T1DM) treated by continuous SC insulin infusion. METHODS: Simulation environment comprising 18 virtual subjects with T1DM was used to simulate overnight closed-loop study with a model predictive control (MPC) algorithm. A 15 h experiment started at 17:00 and ended at 08:00 the next day. Closed loop commenced at 21:00 and continued for 11 h. At 18:00, protocol included meal (50 g carbohydrates) accompanied by prandial insulin. The MPC algorithm advised on insulin infusion every 15 min. Sensor glucose was obtained by combining model-calculated noise-free interstitial glucose with experimentally derived transient and persistent sensor artifacts associated with FreeStyle Navigator (FSN). Transient artifacts were obtained from FSN sensor pairs worn by 58 subjects with T1DM over 194 nighttime periods. Persistent difference due to FSN CE was quantified from 585 FSN sensor insertions, yielding 1421 calibration sessions from 248 subjects with diabetes. RESULTS: Episodes of severe (PG < or = 36 mg/dl) and significant (PG < or = 45 mg/dl) hypoglycemia and significant hyperglycemia (PG > or = 300 mg/dl) were extracted from 18,000 simulated closed-loop nights. Severe hypoglycemia was not observed when FSN CE was less than 45%. Hypoglycemia and hyperglycemia incidence during open loop was assessed from 21 overnight studies in 17 young subjects with T1DM (8 males; 13.5 +/- 3.6 years of age; body mass index 21.0 +/- 4.0 kg/m2; duration diabetes 6.4 +/- 4.1 years; hemoglobin A1c 8.5% +/- 1.8%; mean +/- standard deviation) participating in the Artificial Pancreas Project at Cambridge. Severe and significant hypoglycemia during simulated closed loop occurred 0.75 and 17.11 times per 100 person years compared to 1739 and 3479 times per 100 person years during experimental open loop, respectively. Significant hyperglycemia during closed loop and open loop occurred 75 and 15,654 times per 100 person years, respectively. CONCLUSIONS: The incidence of severe and significant hypoglycemia reduced 2300- and 200-fold, respectively, during stimulated overnight closed loop with MPC compared to that observed during open-loop overnight clinical studies in young subjects with T1DM. Hyperglycemia was 200 times less likely. Overnight closed loop with the FSN and the MPC algorithm is expected to reduce substantially the risk of hypoglycemia and hyperglycemia.

Numerical simulation of the effect of rate of change of glucose on measurement error of continuous glucose monitors.

BACKGROUND: A 5-day in-patient study designed to assess the accuracy of the FreeStyle Navigator Continuous Glucose Monitoring System revealed that the level of accuracy of the continuous sensor measurements was dependent on the rate of glucose change. When the absolute rate of change was less than 1 mg*dl(-1)*min(-1) (75% of the time), the median absolute relative difference (ARD) was 8.5%, with 85% of all points falling within the A zone of the Clarke error grid. When the absolute rate of change was greater than 2 mg*dl(-1)*min(-1) (8% of the time), the median ARD was 17.5%, with 59% of all points falling within the Clarke A zone. METHOD: Numerical simulations were performed to investigate effects of the rate of change of glucose on sensor measurement error. This approach enabled physiologically relevant distributions of glucose values to be reordered to explore the effect of different glucose rate-of-change distributions on apparent sensor accuracy. RESULTS: The physiological lag between blood and interstitial fluid glucose levels is sufficient to account for the observed difference in sensor accuracy between periods of stable glucose and periods of rapidly changing glucose. CONCLUSIONS: The role of physiological lag on the apparent decrease in sensor accuracy at high glucose rates of change has implications for clinical study design, regulatory review of continuous glucose sensors, and development of performance standards for this new technology. This work demonstrates the difficulty in comparing accuracy measures between different clinical studies and highlights the need for studies to include both relevant glucose distributions and relevant glucose rate-of-change distributions.