Intraocular Pressure and Myopia Progression, Axial Length Elongation in Rural Chinese Children.

SIGNIFICANCE: This study reported the relationship between intraocular pressure (IOP) and myopia progression, which helps to understand more comprehensively whether IOP can be an important reference factor to intervene in the progression of myopia. PURPOSE: This study aimed to investigate the association between IOP and myopia progression as well as axial length elongation in rural Chinese children. METHODS: A total of 598 (598 of 878 [68.1%]) children (6 to 17 years) from the baseline Handan Offspring Myopia Study who completed a 3.5-year follow-up vision examination were included. Ocular examinations at both visits included cycloplegic autorefraction, IOP, and axial length measurements. RESULTS: Children with myopia had the highest baseline IOP of the three refractive groups (14.13 ± 1.31, 13.78 ± 1.71, and 13.59 ± 1.64 mmHg in myopes, emmetropes, and hyperopes, respectively, P = .002). However, IOPs showed no significant difference between eyes with or without newly developed myopia (13.63 ± 1.68 vs. 13.89 ± 1.68, P = .16), with or without faster myopia progression (13.75 ± 1.61 vs. 13.86 ± 1.63, P = .46), or with axial length elongation (13.80 ± 1.61 vs. 13.76 ± 1.64, P = .80). The multivariate regression analysis demonstrated that neither baseline refractive error ( ß = -0.082, P = .13) nor baseline axial length ( ß = -0.156, P = .08) was associated with baseline IOP. CONCLUSIONS: Myopic eyes have slightly higher IOP compared with emmetropic and hyperopic eyes, although it was not clinically significant. However, IOP was not found to be associated with either myopia progression or axial length elongation in this cohort sample of rural Chinese children.

Intraocular Pressure, Age, and Central Corneal Thickness in a Healthy Chinese Children Population: The Handan Offspring Myopia Study.

PURPOSE: To assess the distribution and factors related to intraocular pressure (IOP) in a Chinese children population in Northern China. METHODS: 1,238 offspring aged 6 to 18 years, residing in six villages, were recruited for this current study, the Handan Offspring Myopia Study. Participants underwent an interviewer-administered questionnaire and a complete ocular examination, including standardized measurement of IOP with Perkins applanation tonometry. RESULTS: 1,648 eyes of 828 children were included in the analysis. The mean IOP was 13.9 ± 1.6 mmHg. The mean IOP for the study population increased from 13.0 ± 1.5 mmHg for those 6 to 7 years of age to 14.2 ± 1.4 mmHg for those 15 years of age or older (P < .001). The mean central corneal thickness (CCT) was 548.7 ± 32.1 µm, and had no difference among different age groups and gender. In univariate regression analysis, age (0.12 mmHg per 1 year old), height (0.09 mmHg per 5 cm), weight (0.02 mmHg per kg), body mass index (0.07 mmHg per 1 m/kg2), systolic blood pressure (0.06 mmHg per 5 mmHg), CCT (0.06 mmHg per 5 µm), and SE (-0.11 mmHg per 1 D) were correlated with IOP. In multivariate regression analysis, higher IOP was only associated with older ages (p = .002) and thicker CCT (p = .001). CONCLUSION: The mean IOP in healthy rural Chinese children aged 6-18 years is about 14 mmHg, which is lower than in adults in the same locality. The mean IOP is slightly increasing with age during childhood, which is opposite to the result among adults. Age and CCT are the major independent factors associated with IOP.

Analysis of D-dimer cut-off values for overt DIC diagnosis in exertional heat illness.

ABSTRACT: The International Society on Thrombosis and Haemostasis (ISTH) scoring system has been used for diagnosing overt disseminated intravascular coagulation (DIC). However, the cut-off points of fibrin-related markers remain unclear. The ability of the ISTH DIC score and Multiple Organ Dysfunction (MODS) score to predict mortality in cases of exertional heat illness (EHI) was tested. In the process, 3 different D-dimer cut-off values for diagnosing overt DIC were evaluated.Data were obtained on the first day of hospitalization for 76 patients with EHI. The DIC score was calculated according to the ISTH scoring system using 3 D-dimer cut-off values.In predicting mortality, methods 1 and 2 had the same sensitivity and specificity, which were 85% and 73.2%, respectively. The sensitivity for method 3 was 70%. Furthermore, the specificity of the DIC score for method 3 was 89%, which was higher than that of the other 2 methods. The correlation coefficients of the DIC and MODS scores of these 3 methods were 0.757, 0.748, and 0.756, respectively. For the prediction of mortality, the area under the receiver operating characteristic (ROC) curve for the DIC scores of these 3 methods was 0.838, 0.842, and 0.85, respectively. Furthermore, the area under the ROC curve of the MODS score was 0.927.The DIC score had a certain predictive power of a poor outcome of EHI patients, but this was not better than the MODS score. The present data may serve as a reference in selecting the appropriate D-dimer cut-off point for the ISTH DIC score.

Generational Difference of Axial Length and Its Risk Factors in Urban and Rural China.

PURPOSE: To compare the axial length difference (ALD) and the estimated generational axial length shift (ALS) from parents to their children and its risk factors in urban and rural China. METHODS: Participants were enrolled from two longitudinal cohort studies, the Beijing Myopia Progression Study (BMPS) and the Handan Offspring Myopia Study (HOMS). Ocular biometry was performed in both parents and their children. ALD was defined as the difference between the children's axial length and the corresponding parental axial length. Generational ALS was estimated according to a binominal prediction model at 18 years of age. RESULTS: 237 and 380 urban and rural Chinese children (6-17 years) and their parents from the BMPS and HOMS, respectively, were enrolled. Children's axial length was estimated to be closest to the parental axial length at 11 and 9 years of age in the urban and rural areas, respectively; the estimated generational ALS would be 1.53 and 0.57 mm, respectively. Multivariable regression analysis revealed that older children (urban ß = 0.26, p < 0.001; rural ß = 0.11, p < 0.001) and males had larger ALD (urban ß = 0.55, p < 0.001; rural ß = 0.52, p < 0.001) in both areas. Furthermore, urban children with more educated parents (fathers: ß = -0.30, p=0.002; mothers: ß = -0.29, p=0.004) and more outdoor activity (ß = -0.23, p=0.006) had a less ALD. CONCLUSIONS: The urban generational axial length shift was estimated to be approximately 1 mm longer than that of the rural area. These results suggest different environmental effects on the ocular development in these two populations of Chinese children.

Cooling therapy upregulates protein C activation in heat stressed rats: An experimental study.

Protein C (PC) pathway homeostasis is implicated in heat stress (HS). This study determines whether cooling could improve the PC pathway in HS. Fifty-six anesthetized rats were warmed to achieve HS (rectal temperature [Tr] 42°C). These rats were divided into seven groups: (a) control group:sacrifice immediately 15 min after HS; (b) HS+I:sacrifice immediately after 15 min ice-water treatment or (c) 3 hr after HS; (d) HS+C:sacrifice immediately after 15-min cold-water treatment or (e) 3 hr after HS; (f) HS: sacrifice immediately 15 min after HS or (g) 3 hr after HS. Plasma PC, activated protein C (APC), and soluble thrombomodulin (sTM) levels were tested at both time points. After cooling, Tr in the HS+I and HS+C groups significantly decreased, when compared with the HS group, and Tr was significantly lower in the HS+I group than in the HS+C group ( p < 0.05). Furthermore, sTM levels were highest in the HS group among the groups at both time points. Plasma PC and APC levels increased after HS. In the HS+I and HS+C groups, plasma APC levels and the APC/PC ratio significantly increased at both time points. The proportions were significantly higher in the HS+I group than in the HS+C group, and there was no significant increase in APC/PC ratio in the HS group. Cooling exerts an anticoagulant effect following HS by increasing APC levels. Ice-water blanket therapy is more effective than cold-water blanket therapy in increasing APC levels.

Near work, outdoor activity, and myopia in children in rural China: the Handan offspring myopia study.

BACKGROUND: The near work and outdoor activity are the most important environmental risk factors for myopia. However, data from Chinese rural children are relatively rare and remain controversial. Therefore, the purpose of this study was to evaluate the relationship of both near work and outdoor activities with refractive error in rural children in China. METHODS: In this cross-sectional study, 572 (65.1%) of 878 children (6-18 years of age) were included from the Handan Offspring Myopia Study (HOMS). Information from the parents on these children, as well as the parent's non-cycloplegic refraction, were obtained from the database of the Handan Eye Study conducted in the years 2006-2007. A comprehensive vision examination, including cycloplegic refraction, and a related questionnaire, were assessed on all children. RESULTS: The overall time spent on near work and outdoor activity in the children was 4.8 ± 1.6 and 2.9 ± 1.4 h per day, respectively. Myopic children spent more time on near work (5.0 ± 1.7 h vs.4.7 ± 1.6 h, p = 0.049), while no significant difference was found in outdoor activity hours (2.8 ± 1.3 h vs. 3.0 ± 1.4 h, p = 0.38), as compared to non-myopic children. In the multiple logistic analysis, in general, no association between near work and myopia was found after adjusting for the children's age, gender, parental refractive error, parental educational level, and daily outdoor activity hours [odds ratio (OR), 95% confidence interval (CI): 1.10, 0.94-1.27]. However, a weak protective effect of the outdoor activity on myopia was found (OR, 95% CI: 0.82, 0.70-0.96), after adjusting for similar confounders. CONCLUSIONS: In general, no association between near work and myopia was found, except for the high near work subgroup with moderate outdoor activity levels. A weak protective effect of outdoor activity on myopia in Chinese rural children was observed.

Eye exercises of acupoints: their impact on myopia and visual symptoms in Chinese rural children.

BACKGROUND: Chinese traditional "eye exercises of acupoints" have been advocated as a compulsory measure to reduce visual symptoms, as well as to retard the development of refractive error, among Chinese students for decades. The exercises are comprised of a 5-min, bilateral eye acupoint self-massage. This study evaluated the possible effect of these eye exercises among Chinese rural students. METHODS: Eight hundred thirty-six students (437 males, 52.3 %), aged 10.6 ± 2.5 (range 6-17) years from the Handan Offspring Myopia Study (HOMS) who completed the eye exercises and vision questionnaire, the convergence insufficiency symptom survey (CISS) questionnaire, and had a cycloplegic refraction were included in this study. RESULTS: 121 (14.5 %) students (64 males, 52.9 %) performed the eye exercises of acupoints in school. The multiple odds ratio (OR) and 95 % confidence interval (CI) for those having a "serious attitude" towards performing the eye exercises (0.12, 0.03-0.49) demonstrated a protective effect for myopia, after adjusting for the children's age, gender, average parental refractive error, and the time spent on near work and outdoor activity. The more frequently, and the more seriously, the students performed the eye exercises each week, the less likely was their chance of being myopic (OR, 95 % CI: 0.17, 0.03-0.99), after adjusting for the same confounders. However, neither the "seriousness of attitude" of performing the eye exercises (multiple ß coefficients: -1.58, p = 0.23), nor other related aspects of these eye exercises, were found to be associated with the CISS score in this sample. CONCLUSIONS: The traditional eye exercises of acupoints appeared to have a modest protective effect on myopia among these Chinese rural students aged 6-17 years. However, no association between the eye exercises and near vision symptoms was found.

Generational difference of refractive error and risk factors in the Handan Offspring Myopia Study.

PURPOSE: To report the refractive error difference (RED) between parents and their children, and its risk factors, in a rural area of China. METHODS: Children (6-17 years) and their parents (36.2 ± 4.1 years) from the Handan Offspring Myopia Study (HOMS) were enrolled. Cycloplegic autorefraction (cyclopentolate 1%, Topcon KR8800) of the children and noncycloplegic autorefraction of their parents were assessed. A detailed vision-based questionnaire was also completed. Refractive error difference was defined as the difference between the parental spherical equivalent (SE) and their children's SE. Generational myopic shift was defined as the estimated RED when a child would be 18 years old according to a prediction model. RESULTS: Three hundred fifty-six pairs of parents and 585 children were enrolled. The RED (median, quartiles) increased from -1.33 (-1.99, -0.98) diopters (D) in children aged 6 to 7 years to 0.81 (-0.16, 2.28) D in children aged 16 to 17 years. The children's SE was predicted to approach the parental SE at 14 years of age. Moreover, the children's estimated myopic shift would be 1.03 D. Multiple linear regression revealed that older children (ß = 0.23 D/y, P < 0.0001) and girls (ß = 0.24, P = 0.01) tended to have a higher RED. CONCLUSIONS: In this rural Chinese population, the children's refraction was estimated to be similar to the parental refraction at 14 years of age. Moreover, the generational myopic shift was estimated to be approximately 1 D at 18 years of age. These data suggest that the generational difference reflects the increasing prevalence of myopia in the younger generation, which is likely due to changes in environmental exposure.

Near work, outdoor activity, and their association with refractive error.

PURPOSE: To assess the relationship between near work, outdoor activity, and refractive error in schoolchildren in Beijing. METHODS: The Beijing Myopia Progression Study is a hospital-based myopia study, in which 386 students from primary (aged 6 to 12 years) and secondary (aged 13 to 17 years) schools in the inner city of Beijing were enrolled. Cycloplegic refraction and a detailed questionnaire probing near, intermediate, and distance visual activities were completed. RESULTS: Three hundred seventy (95.9%) of 386 students with complete cycloplegic autorefraction and myopia questionnaire data were enrolled in this study. Children with more near work time did not exhibit a significantly more myopic refraction in both the primary and secondary school levels after adjusting for the children's gender, outdoor activity time, and average parental refractive error. A significant association between outdoor activity time (in hours per day) and the children's spherical equivalent (in diopters) was found in the primary school students (ß = 0.27, p = 0.03) but not in the secondary school students (ß = 0.04, p = 0.70) after adjusting for similar confounders. The time spent on outdoor sports and outdoor leisure in the primary school students was also significantly associated with the children's spherical equivalent (ß = 0.46, p = 0.04 and ß = 0.31, p = 0.02, respectively). Primary school students with more time outdoors exhibited relatively less myopic refraction than their peers (ptrend = 0.0003), but this relation was not demonstrated in the secondary school children (ptrend = 0.53) after adjusting for similar confounders. CONCLUSIONS: Higher levels of outdoor activity were associated with less myopic refraction in primary school students in the inner city of Beijing. Near work activity was not found to be associated with refraction at either school level.

Rationale, design, and demographic characteristics of the Handan Offspring Myopia Study.

PURPOSE: The Handan Offspring Myopia Study (HOMS) aims to investigate the familial associations of myopia between parents and their offspring. METHODS: Children aged 6-18 years, residing in 6 villages where all people aged ≥30 years had participated in The Handan Eye Study in 2006-2007, were selected for the current eye study between March and June 2010. A mobile clinic was set up in the 6 villages for comprehensive eye examinations, including visual acuity, ocular biometry, cycloplegic autorefraction and retinal photography. RESULTS: Of 1238 eligible individuals, 878 children (70.2%; 52.6% male) from 541 families were recruited. Mean age of the children was 10.5 ± 2.5 years. The prevalence of myopia (spherical equivalent refraction <-0.5 diopter) was 23.5% (males 16.8%, females 30.8%). The prevalence of low vision (presenting visual acuity ≥20/400 but <20/60) in the better eye was 7.1%. A higher number of females had low vision at the time of presentation (9.2%) compared to males (5.2%, p = 0.02). The prevalence of low vision in the worse eye was 10.6% (males 6.7%, females 14.9%, p < 0.001). The majority of visual impairment in the better-seeing (56/62, 90.3%) as well as the worse-seeing (84/93, 90.3%) eye was correctable. CONCLUSIONS: The HOMS examined about 70% of eligible Han Chinese offspring of Handan Eye Study participants in a rural region of northern China. Results from the HOMS will provide key information about the prevalence of refractive errors and eye diseases in rural Chinese children.

Eye exercises of acupoints: their impact on refractive error and visual symptoms in Chinese urban children.

BACKGROUND: Traditional Chinese eye exercises of acupoints involve acupoint self-massage. These have been advocated as a compulsory measure to reduce ocular fatigue, as well as to retard the development of myopia, among Chinese school children. This study evaluated the impact of these eye exercises among Chinese urban children. METHODS: 409 children (195 males, 47.7%), aged 11.1 ± 3.2 (range 6-17) years, from the Beijing Myopia Progression Study (BMPS) were recruited. All had completed the eye exercise questionnaire, the convergence insufficiency symptom survey (CISS), and a cycloplegic autorefraction. Among these, 395 (96.6%) performed the eye exercises of acupoints. Multiple logistic regressions for myopia and multiple linear regressions for the CISS score (after adjusting for age, gender, average parental refractive error, and time spent doing near work and outdoor activity) for the different items of the eye exercises questionnaire were performed. RESULTS: Only the univariate odds ratio (95% confidence interval) for "seriousness of attitude" towards performing the eye exercises of acupoints (0.51, 0.33-0.78) showed a protective effect towards myopia. However, none of the odds ratios were significant after adjusting for the confounding factors. The univariate and multiple ß coefficients for the CISS score were -2.47 (p = 0.002) and -1.65 (p = 0.039), -3.57 (p = 0.002) and -2.35 (p = 0.042), and -2.40 (p = 0.003) and -2.29 (p = 0.004), for attitude, speed of exercise, and acquaintance with acupoints, respectively, which were all significant. CONCLUSIONS: The traditional Chinese eye exercises of acupoints appeared to have a modest effect on relieving near vision symptoms among Chinese urban children aged 6 to 17 years. However, no remarkable effect on reducing myopia was observed.

Generational difference of refractive error in the baseline study of the Beijing Myopia Progression Study.

AIMS: To report the refractive error difference (RED) between parents and their children and the estimated single generational myopic shift in an urban area in China. METHODS: 395 children aged 6-17 years and their parents, who had been enrolled in the Beijing Myopia Progression Study were included. Cycloplegic and non-cycloplegic refraction of the children and parents were performed, respectively. RED was defined as the difference between the average parental spherical equivalent (SE) and the average SE of their children. Binomial fitted curves of RED were plotted as a function of the children's age. Generational myopic shift was defined as the estimated RED according to the prediction model at the age of 18 years. RESULTS: 395 families were enrolled. The RED was positively correlated with the children's age (rspearman=0.58, p<0.001). The RED (median (25th and 75th percentile)) was -1.88 (-3.23 to -1.00) dioptres (D) in children at 6.0-7.9 years of age, and it increased to 1.53 (-0.12 to 3.44) D in children at 16.0-17.9 years of age. The SE of the children approached the average SE of their parents at the age of 11 years. At the age of 18 years, the children's estimated myopic shift would be 1.94 D. CONCLUSIONS: In this sample, children's refractive errors at the age of 11 years were already similar to their parents. Moreover, the estimated myopia in children at the age of 18 years would be up to 2.0 D higher than their parents. This remarkable single-generation myopic shift indicates that there are likely effects of environmental factors on myopia development in urban Chinese children.