Effect of Contact Lenses on Contrast Sensitivity under Various Lighting Conditions

Purpose: To assess contrast sensitivity in clear and colored soft contact lenses under different lighting conditions. Methods: This study was performed on 34 medical students. Visual acuity was measured using a tumbling E chart at a distance of 6 m, and contrast sensitivity was determined by Pelli Robson chart at a distance of 1 m. These tests were repeated in mesopic (3 lux) and glare (2000 lux) conditions. Then, a clear contact lens was applied to one eye and a colored contact lens was applied to the other. After 2 hr, visual acuity and contrast sensitivity were measured for each individual. The results were compared with and without contact lenses under normal, mesopic, and glare conditions. Results: The mean refractive error was 0.44 ± 0.20 diopters. Repeated measures ANOVA showed a decline in contrast sensitivity with colored and clear contact lenses as compared to no-lens condition (P < 0.001). Additionally, lighting conditions had a significant impact on contrast sensitivity (P < 0.001); contrast sensitivity was lower in mesopic and glare conditions than under normal lighting condition. Conclusion: In addition to the drop in contrast sensitivity under unusual lighting conditions (e.g., glare and mesopic), wearing soft contact lenses can further reduce contrast sensitivity in different lighting conditions. Therefore, people who wear contact lenses should be aware of this reduction in visual performance in conditions like driving at night or in the fog

Normative values of Pelli Robson contrast sensitivity test in southeast Iran: A tropical area

Introduction: This study aimed to evaluate the distribution of contrast sensitivity (CS) using Pelli Robson test in normal individuals over seven years old living in Zahedan and examine its relationship with age, gender, and refractive errors. Methods: In this cross-sectional study, simple sampling was performed on the patients aged over seven years and their attendants who had referred to Al-Zahra eye hospital in Zahedan. Complete ophthalmic examinations including vision and refraction assessment, biomicroscopy, and CS evaluation were carried out for all subjects. To evaluate CS, Pelli Robson chart was used at a distance of one meter. The logarithmic CS value of the last triplet in which the patient could accurately read two words was regarded as his/her CS value. Results: Of the 150 patients (300 eyes), 70 (46.66%) were male. The mean age of the subjects was 34.56±16.15 years (ranged from seven to 78 years). The mean and standard deviation of the CS score in two modes of monocular and binocular vision were 1.45±0.19 and 1.57±0.19 log unit, respectively. The mean CS score was not significantly different between men and women (P>0.454), but it decreased significantly with the age (P=0.000). CS was higher in individuals with emmetropia than those with myopia and hypermetropia (P=0.000). There was also a significant correlation between cylinder magnitude and CS (P=0.000). Conclusion: Although Pelli Robson test evaluates CS at low and constant spatial frequencies, its distribution is significantly different among different age groups and even among individuals with different values of refractive errors

Walking Ability, Participation, and Quality of Life in Children with Spastic Diplegic Cerebral Palsy: A Path Analysis Study

  Objectives This study aims to design a conceptual model for the effect of various factors on walking ability, participation, and quality of life in children with spastic diplegic cerebral palsy (SDCP) and test it based on field data using path analysis. Materials & Methods This cross-sectional study was performed on 181 children with SDCP. The following were used to measure each of the variables: the Modified Ashworth Scale, the Micro Manual Muscle Tester, the Timed Up and Go Test (TUG), the Boyd and Graham test, the goniometer, weight and height, the Gross Motor Function Classification System, the Life Habits Questionnaire, and cerebral palsy Quality of Life Questionnaire for Children. The structural model was tested in Amos 17. Results All paths of the proposed model were significant (P <0.05). Among evaluated variables, muscle strength (B = -0.466), balance (B = 0.326), and spasticity (B = 0.143) affected walking ability. Moreover, as an intermediate factor, walking ability affected the subjects’ participation (B = -0.819) and quality of life (B = -0.183). Conclusion Muscle strength, balance, and spasticity are the most influential factors in the walking ability of children with SDCP. Furthermore, walking ability and participation are two critical factors in promoting the quality of life of these children

Financial Sanctions and Economic Growth: An Intervention Time-series Approach

In the present study, the authors examined the impact of financial sanctions on economic growth using Iran's data and intervention time-series analysis over the period 2005-2017. Financial sanctions targeted the country's financial resources and increased interest rates and medium- and long-term financing costs. In general, financial sanctions adversely affected the financial sector. In this regard, blocking of assets and restricted access to financial and foreign exchange resources, depreciated domestic currency, reduced investment, exports, and production along with increased inflation and unemployment ultimately reduced economic growth. The results indicated the effectiveness of financial sanctions on economic growth in the short-run. However, during the third period (2010-2014), when severe and multilateral financial sanctions are imposed, the coefficient is negative (0.54), which is higher, compared to the other periods. As the economic sanctions of Iran have intensified, the economic growth has slowed down. Nevertheless, in the long run, financial sanctions have had a weaker negative effect of 0.19 on the economic growth

The Impact of Financial Sanctions on Capital Inflow and Outflow (case of Iran)

The paper aims to examine the impact of financial sanctions on capital inflow and outflow in Iran. The research question is about examining the effect of financial sanctions on FDI inflow and capital outflow in Iran. We used the intervention model as an econometric method to estimate the impact during 2005-2019. The paper discussed three periods. From 2005 to 2010, severe financial sanctions negatively affected FDI, and capital outflow was positive. From 2011 to 2015, severe and multilateral financial sanctions were implemented, adversely affecting FDI. There is a positive relationship between financial sanctions and capital outflow. In the third period, i.e., 2016-2019, when financial sanctions and implementation of JCPOA and the withdrawal of the United States happened, the overall effect on FDI inflow is negative. Although Iran absorbed about $2 billion of FDI, with the withdrawal of the United States from JCPOA and the return of secondary U.S. sanctions, the reduction of FDI happened again. On capital outflow, the sanction has a positive effect on capital outflow. Altogether, during 2005-2019, financial sanctions adversely affected FDI inflow and increased capital outflow in Iran

Financial Sanctions and the Imports of Intermediate and Capital Goods in Iran: DID Method

During the last three decades, financial sanctions have been imposed on Iran by the United States, the European Union, and the United Nations Security Council. These sanctions have had various effects on Iran's economic sectors. This paper aims at estimating the effect of financial sanctions on the import of capital and intermediate goods in Iran, which was carried out for two independent time periods. The first period (2010-2013) includes multilateral financial sanctions, and the second period (2016-2019) includes multilateral sanctions and the withdrawal of the United States from the JCPOA. We examined the impact using the difference-in-difference (DID) method. The results of the first period indicate that the decrease in the imports of capital and intermediate goods in Iran depends more on the countries that "provided the sanctions plan" than the countries that did not provide the sanctions plan, because the coefficient of dummy variable for implementation in the random effects model is statistically significant. The negative effect of 0.007 on imports shows that the effect is weak, because this group of countries behaved differently. Since the implementation of multilateral financial sanctions in 2012, some countries such as Australia greatly reduced the export of capital and intermediate goods to Iran, but other countries such as Italy increased the export of capital and intermediate goods to Iran. In the second period, the random effects model is statistically significant. In this model, the negetive effect of 0.22 on imports indicates a significant effect. Therefore, the reduction of Iran's imports in this period depends more on the countries that provided the sanctions plan than the countries that did not provide the plan. Since the withdrawal of the United States from the JCPOA in 2018, countries such as Korea, Germany, Russia, UK and Italy reduced the export of capital and intermediate goods to Iran. The comparison of two independent periods indicates that in the first period, the major share of Iran’s imports belongs to the UAE, and in the second period, it belongs to China. Turkey has been Iran's trading partner in both periods and since the imposition of sanctions, it has had an 8% share in the export of capital and intermediate goods to Iran, and with the withdrawal of the United States from the JCPOA, this share has increased to 13%

Refractive Status in Low Birth Weight 4 to 6-Year-Old Children with or without Retinopathy of Prematurity

Background and purpose: Premature birth is common worldwide and can affect the development of brain structures, such as the optic nerve. Eye diseases are very common in low birth weight children and premature children. Vision defects associated with premature birth include Retinopathy of premature babies (ROP), decreased visual acuity, strabismus, amblyopia, and various types of refractive errors. Studies have shown that the occurrence of myopia in children born prematurely is negatively correlated with gestational age and birth weight and is directly related to the severity of retinopathy of prematurity(ROP). Advances in neonatal intensive care unit services have led to a significant increase in the survival rate of premature infants and subsequent medical problems in these children. This study was designed to determine the prevalence of refractive errors in 4-6-year-old children born with a birth weight of less than 2000 grams and gestational age of less than 34 weeks and normal children admitted to the neonatal department of Bou-Ali Sina Hospital in Sari in 2016-2018. Materials and methods: This study was a cross-sectional descriptive study on 43 children aged 4-6 years who were born with a weight of less than 2000 grams and gestational age of less than 34 weeks, and 17 normal children who were admitted in the neonatal department of Bou-Ali Sina Hospital due to neonatal jaundice. The study subjects were in four groups: 12 subjects in group A (ROP cases without injection), 14 subjects in group B (ROP cases with injection), 17 subjects in group C (cases with birth weight less than 2000 grams and gestational age less than 34 weeks without ROP), and 17 normal subjects in group D. Uncorrected distance visual acuity was measured using E-chart. Dry and cyclo refraction (using cyclopentolate 1%) were measured using an autorefractometer. Finally, the fundus was examined using a biomicroscope and 90 diopter lens. Statistical analysis was performed using SPSS software, version 26. Results: of the 60 studied subjects, 46.67% were females and 53.33% were males, and there was no significant difference in the prevalence of the two sexes between the groups (P=0.146). In total, 12.1% of the studied subjects were myopie, 34.5% were emmetrope, and 53/4% were hypermetrope. Although the prevalence of hypermetropia was higher than other types of refractive errors in all groups, the prevalence of myopia was higher in those with ROP than in groups without ROP, and there was a significant difference in the prevalence of refractive errors in different groups (P=0.025). There was no significant difference between the prevalence of the different types of astigmatism in the studied groups (P=0.304) and with the rule astigmatism was the most common type among all groups. There was a significant and direct relationship between gestational age and birth weight with cyclo-equivalent sphere, which means that the lesser gestational age (P=0.356, r=0.006) and birth weight (P=0.002, r=0.387), the higher the probability of myopia. Conclusion: Considering the higher prevalence of myopia in low birth weight children, especially in children with ROP, it is necessary to formulate a regular program to screen this category of children to prevent refractive errors, especially myopia in the future

Prevalence of color vision deficiency among arc welders

Purpose: This study was performed to investigate whether occupationally related color vision deficiency can occur from welding. Methods: A total of 50 male welders, who had been working as welders for at least 4 years, were randomly selected as case group, and 50 age matched non-welder men, who lived in the same area, were regarded as control group. Color vision was assessed using the Lanthony desatured panel D-15 test. The test was performed under the daylight fluorescent lamp with a spectral distribution of energy with a color temperature of 6500 K and a color rendering index of 94 that provided 1000 lx on the work plane. The test was carried out monocularly and no time limit was imposed. All data analysis were performed using SPSS, version 22. Results: The prevalence of dyschromatopsia among welders was 15% which was statistically higher than that of nonwelder group (2%) (p = 0.001). Among welders with dyschromatopsia, color vision deficiency in 72.7% of cases was monocular. There was positive relationship between the employment length and color vision loss (p = 0.04). Similarly, a significant correlation was found between the prevalence of color vision deficiency and average working hours of welding a day (p = 0.025). Conclusions: Chronic exposure to welding light may cause color vision deficiency. The damage depends on the exposure duration and the length of their employment as welders

The prevalence of uncorrected refractive errors in underserved rural areas

Purpose: To determine the prevalence of uncorrected refractive errors, need for spectacles, and the determinants of unmet need in underserved rural areas of Iran. Methods: In a cross-sectional study, multistage cluster sampling was done in 2 underserved rural areas of Iran. Then, all subjects underwent vision testing and ophthalmic examinations including the measurement of uncorrected visual acuity (UCVA), best corrected visual acuity, visual acuity with current spectacles, auto-refraction, retinoscopy, and subjective refraction. Need for spectacles was defined as UCVA worse than 20/40 in the better eye that could be corrected to better than 20/40 with suitable spectacles. Results: Of the 3851 selected individuals, 3314 participated in the study. Among participants, 18.94% [95% confidence intervals (CI): 13.48â24.39] needed spectacles and 11.23% (95% CI: 7.57â14.89) had an unmet need. The prevalence of need for spectacles was 46.8% and 23.8% in myopic and hyperopic participants, respectively. The prevalence of unmet need was 27% in myopic, 15.8% in hyperopic, and 25.46% in astigmatic participants. Multiple logistic regression showed that education and type of refractive errors were associated with uncorrected refractive errors; the odds of uncorrected refractive errors were highest in illiterate participants, and the odds of unmet need were 12.13, 5.1, and 4.92 times higher in myopic, hyperopic and astigmatic participants as compared with emmetropic individuals. Conclusion: The prevalence of uncorrected refractive errors was rather high in our study. Since rural areas have less access to health care facilities, special attention to the correction of refractive errors in these areas, especially with inexpensive methods like spectacles, can prevent a major proportion of visual impairment. Keywords: Uncorrected refractive errors, Population-based study, Unmet nee

Quality of sunglasses available in the Iranian market; a study with emphasis on sellers′ license

Context: Sunglasses should follow minimum requirements to sufficiently protect eyes. It is not known whether all items obtainable from the market are appropriately designed. Aims: To compare ultraviolet (UV)-protective properties of commercially available sunglasses obtained from authorized and unauthorized Iranian sellers. Settings and Study Design: An analytic-descriptive study performed in a metropolitan area (Tehran). Materials and Methods: Using a UV-visible standard spectrophotometer, the percentage transmittance was scanned between 280 and 400 nm in 348 pairs of nonprescription sunglasses (price range: 20-80 US$) obtained anonymously and randomly from authorized (permitted by the Ministry of Health, 189 pairs) and unauthorized (159 pairs) sellers in the Iranian capital city, Tehran. The Australian/New Zealand Standard (AS/NZS) and the American National Standards Institute [ANSI] standards were followed. Statistical Analysis: Chi-square test, independent samples t-test or Mann-Whitney U-test. Results UV-protective properties of the sunglasses obtained from authorized sellers complied with AS/NZS and ANSI guidelines in 92.6% and 95.2% of items, respectively. The corresponding rates for sunglasses obtained from unauthorized sellers were 0% and 8.2%, respectively (P < 0.001 for both). The rate of defective polarizing capability of lenses was 27.4% in sunglasses obtained from authorized sellers versus 90.4% in sunglasses obtained from unauthorized sellers (P < 0.001). Neither brand nor price played significant contributions to UV protection/lens polarizing capability of sunglasses obtained from authorized sellers. Conclusions: Sunglasses provided by unauthorized sellers are alarmingly unreliable and could be potentially hazardous for the eye. Brand and price do not guarantee optimal protection against UV radiation or polarizing performance of the lens