Safety of Spectacles for Children's Vision: A Cluster-Randomized Controlled Trial.

PURPOSE: To study safety of children's glasses in rural China, where fear that glasses harm vision is an important barrier for families and policy makers. DESIGN: Exploratory analysis from a cluster-randomized, investigator-masked, controlled trial. METHODS: Among primary schools (n = 252) in western China, children were randomized by school to 1 of 3 interventions: free glasses provided in class, vouchers for free glasses at a local facility, or glasses prescriptions only (Control group). The main outcome of this analysis is uncorrected visual acuity after 8 months, adjusted for baseline acuity. RESULTS: Among 19 934 children randomly selected for screening, 5852 myopic (spherical equivalent refractive error <=-0.5 diopters) eyes cif 3001 children (14.7%, mean age 10.5 years) had VA <= 6/12 without glasses correctable to >6/12 with glasses, and were eligible. Among these, 1903 (32.5%), 1798 (30.7%), and 2151 (36.8%) were randomized to Control, Voucher, and Free Glasses, respectively. Intention-to-treat analyses were performed on all 1831 (96.2%), 1699 (94.5%), and 2007 (93.3%) eyes of children with follow-up in Control, Voucher, and Free Glasses groups. Final visual acuity for eyes of children in the treatment groups (Free Glasses and Voucher) was significantly better than for Control children, adjusting only for baseline visual acuity (difference of 0.023 logMAR units [0.23 vision chart lines, 95% CI: 0.03, 0.43]) or for other baseline factors as well (0.025 logMAR units [0.25 lines, 95% CI 0.04, 0.45]). CONCLUSION: We found no evidence that spectacles promote decline in uncorrected vision with aging among children. (C) 2015 by Elsevier Inc. All rights reserved.ONESIGHT (MASON, OHIO); LUXOTTICA-CHINA (SHANGHAI); ESSILOR-CHINA (SHANGHAI); CREDIT LYONAIS Securities Asia (Asia Pacific Markets; Hong Kong); Charity Aid Foundation (Sydney); Chinese government; Ulverscroft Foundation; OneSight, Luxottica-China; Essilor-ChinaSCI(E)[email protected]

Assessment of cataract surgical outcomes in settings where follow-up is poor: PRECOG, a multicentre observational study

Background Poor follow-up after cataract surgery in developing countries makes assessment of operative quality uncertain. We aimed to assess two strategies to measure visual outcome: recording the visual acuity of all patients 3 or fewer days postoperatively (early postoperative assessment), and recording that of only those patients who returned for the fi nal follow-up examination after 40 or more days without additional prompting. Methods Each of 40 centres in ten countries in Asia, Africa, and Latin America recruited 40–120 consecutive surgical cataract patients. Operative-eye best-corrected visual acuity and uncorrected visual acuity were recorded before surgery, 3 or fewer days postoperatively, and 40 or more days postoperatively. Clinics logged whether each patient had returned for the fi nal follow-up examination without additional prompting, had to be actively encouraged to return, or had to be examined at home. Visual outcome for each centre was defi ned as the proportion of patients with uncorrected visual acuity of 6/18 or better minus the proportion with uncorrected visual acuity of 6/60 or worse, and was calculated for each participating hospital with results from the early assessment of all patients and the late assessment of only those returning unprompted, with results from the fi nal follow-up assessment for all patients used as the standard. Findings Of 3708 participants, 3441 (93%) had fi nal follow-up vision data recorded 40 or more days after surgery, 1831 of whom (51% of the 3581 total participants for whom mode of follow-up was recorded) had returned to the clinic without additional prompting. Visual outcome by hospital from early postoperative and fi nal follow-up assessment for all patients were highly correlated (Spearman’s rs=0·74, p<0·0001). Visual outcome from fi nal followup assessment for all patients and for only those who returned without additional prompting were also highly correlated (rs=0·86, p<0·0001), even for the 17 hospitals with unprompted return rates of less than 50% (rs=0·71, p=0·002). When we divided hospitals into top 25%, middle 50%, and bottom 25% by visual outcome, classifi cation based on fi nal follow-up assessment for all patients was the same as that based on early postoperative assessment for 27 (68%) of 40 centres, and the same as that based on data from patients who returned without additional prompting in 31 (84%) of 37 centres. Use of glasses to optimise vision at the time of the early and late examinations did not further improve the correlations. Interpretation Early vision assessment for all patients and follow-up assessment only for patients who return to the clinic without prompting are valid measures of operative quality in settings where follow-up is poor

Synergistic Effects of Hypofibrinolysis and Genetic and Acquired Risk Factors on the Risk of a First Venous Thrombosis

Frits Rosendaal and colleagues show that the combination of hypofibrinolysis with oral contraceptive use, immobilization, or factor V Leiden results in a risk of venous thrombosis that exceeds the sum of the individual risks

Reply (Correspondence) to Safety of Spectacles for Children’s Vision: A Cluster-Randomized Controlled Trial

We appreciate the interest of Galvis and associates in our work.1 It has been suggested that undercorrection of children's refractive error might retard myopia progression. Previous studies,2,3 limited by size, have generally not been consistent with this. We performed a post hoc analysis on data from our large trial of spectacle provision in China and found no evidence of worsening visual acuity (VA) among children randomized to receive glasses compared to controls. In fact, the final uncorrected VA of Treatment Group children was significantly better than that of controls

The Impact of the Fibrinolytic System on the Risk of Venous and Arterial Thrombosis

In this review we discuss the association of overall hypofibrinolysis and individual fibrinolytic protein levels with venous and arterial thrombosis. Decreased overall fibrinolytic potential and high plasma levels of thrombin-activatable fibrinolysis inhibitor have been consistently associated with risk of venous thrombosis, whereas little evidence exists for a role of plasminogen, α2-antiplasmin, tissue plasminogen activator, and plasminogen activator inhibitor 1. Overall fibrinolytic potential has been associated with arterial thrombosis in young individuals, but studies on the individual components gave conflicting results. These inconsistent results could be a consequence of nonfibrinolytic properties of fibrinolytic proteins, including roles in inflammation, vascular remodeling, atherosclerosis, and the metabolic syndrome. The nonfibrinolytic properties of these proteins may have opposing effects on development of arterial disease as compared with the lytic properties, which may explain opposite results in different studies with slightly different population characteristics. These properties may be more relevant in arterial than in venous thrombosis.\ud \u

Effect of providing free glasses on children's educational outcomes in China: cluster randomized controlled trial

Development and application of statistical models for medical scientific researc

Modulación completa del plano complejo mediante pantallas de cristal líquido. Aplicación a la representación de hologramas de Fresnel digitales.

[spa] En el presente trabajo se analiza el uso de pantallas de cristal líquido para obtener la modulación completa del plano complejo. Esta modulación se emplea para la representación de hologramas de Fresnel digitales. Primero se analiza el comportamiento de la reconstrucción de los hologramas de Fresnel a distintas distancias utilizando solo parte de la información compleja: amplitud, fase, parte real o parte imaginaria. Después se presentan los modelos de las pantallas de cristal líquido que se utilizan y las distintas configuraciones para obtener la modulación completa del plano complejo mediante el uso de dos pantallas acopladas. Un primer sistema utiliza dos pantallas de transmisión de cristal líquido nemático acopladas en cascada, con la que se emplean dos métodos para realizar el ajuste de la amplitud y la fase que representa la información del holograma. El siguiente método utiliza la suma de dos pantallas ferroeléctricas de reflexión dispuestas en una configuración similar al interferómetro de Michelson, con la que se obtiene la modulación compleja completa mediante la suma de las partes real e imaginaria. Por último se analiza el caso de utilizar la suma de dos pantallas de transmisión con configuraciones diferentes a la solo real o solo imaginaria, dispuestas en una arquitectura similar a la de un interferómetro de Mach-Zehnder. En todos los casos se presentan resultados simulados y experimentales.[eng] In this work we analyze the use of liquid crystal devices to obtain full modulation of the complex plane. This full complex modulation is used to display digital Fresnel holograms. First we analyze the behaviour of the reconstruction of Fresnel holograms at several distances using only part of the complex information: amplitude, phase, real or imaginary part. We also present the models of the liquid crystal devices used and the different working configurations using two coupled devices to obtain full complex modulation of the complex plane. The first system uses two transmissive devices in a cascade architecture, which we use two different methods to adjust the amplitude and the phase that represent the information of the hologram. The next system uses the addition of two reflective ferroelectric devices in a Michelson interferometer configuration, obtaining the full complex modulation by adding the real and imaginary parts. The last system uses the addition of two transmissive devices with different operating curves than the only-real or the only-imaginary. The setup with the two devices is like a Mach-Zehnder interferometer. In all cases simulated and experimental results are presented