BackgroundIn many parts of the world, including in China, extreme heat events or heat waves are likely to increase in intensity, frequency, and duration in light of climate change in the next decades. Risk perception and adaptation behaviors are two important components in reducing the health impacts of heat waves, but little is known about their relationships in China. This study aimed to examine the associations between risk perception to heat waves, adaptation behaviors, and heatstroke among the public in Guangdong province, China.MethodsA total of 2,183 adult participants were selected using a four-stage sampling method in Guangdong province. From September to November of 2010 each subject was interviewed at home by a well-trained investigator using a structured questionnaire. The information collected included socio-demographic characteristics, risk perception and spontaneous adaptation behaviors during heat wave periods, and heatstroke experience in the last year. Chi-square tests and unconditional logistic regression models were employed to analyze the data.ResultsThis study found that 14.8%, 65.3% and 19.9% of participants perceived heat waves as a low, moderate or high health risk, respectively. About 99.1% participants employed at least one spontaneous adaptation behavior, and 26.2%, 51.2% and 22.6% respondents employed <4, 4–7, and >7 adaptation behaviors during heat waves, respectively. Individuals with moderate (OR=2.93, 95% CI: 1.38-6.22) or high (OR=10.58, 95% CI: 4.74-23.63) risk perception experienced more heatstroke in the past year than others. Drinking more water and wearing light clothes in urban areas, while decreasing activity as well as wearing light clothes in rural areas were negatively associated with heatstroke. Individuals with high risk perception and employing <4 adaptation behaviors during heat waves had the highest risks of heatstroke (OR=47.46, 95% CI: 12.82-175.73).ConclusionsThere is a large room for improving health risk perception and adaptation capacity to heat waves among the public of Guangdong province. People with higher risk perception and fewer adaptation behaviors during heat waves may be more vulnerable to heat waves.

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Purpose: To compare the accuracy for various screening tests and their combined uses for myopia screening among children and adolescents and explore age-specific cutoffs. Design: Cross-sectional study. Methods: A total of 6017 children and adolescents aged 4 to 15 years participated in the study. Uncorrected visual acuity (UCVA, recorded in decimal notation), cycloplegic and noncycloplegic refraction (NCR), axial length (AL), and corneal curvature radius (CR) examinations were performed. Cycloplegic spherical equivalent À0.50 D was considered as the gold standard for myopia. Receiver operating characteristic (ROC) curves were drawn to determine optimal cutoffs for all age groups, and sensitivity, specificity, as well as screening prevalence of myopia were calculated. Results: The overall estimate of myopia prevalence was 31.8% using the gold standard. The sensitivity and specificity of the UCVA alone for the commonly used cutoff (1.0) were 97.7% and 33.1%, respectively. The areas under the ROC curve were optimally estimated to be 0.985 (95% CI, 0.982-0.988) for the combined use of UCVA and NCR tests, and 0.987 (95% CI, 0.983-0.989) for the combined use of AL/CR and NCR tests, with no significant difference (P ¼ 0.208). The best cutoffs for UCVA-NCR combinations were UCVA <1.0 and NCR <À0.25 D in 4 to 6 years; UCVA <1.0 and NCR <À0.50 D in 7 to 12 years; UCVA <0.8 and NCR <À0.75 D in 13 to 15 years. If those screening positive were all referred to clinics and corrected with cycloplegic autorefraction data, the relative difference between screening prevalence and the actual prevalence by the gold standard would reduce from 13.2% to 4.7%. Conclusions: UCVA test alone for detecting myopia demonstrated a poorer accuracy among these tests. The combined use of UCVA and NCR tests and the combined use of AL/CR and NCR tests achieved optimal accuracy for myopia screening. Setting age-specific cutoffs would increase the accuracy, and the prevalence obtained from primary screening should be corrected according to the data of cycloplegic refraction after referral, especially in younger ages.

Background It is generally believed that a 1‐mm axial length (AL) elongation of the eye corresponds to a −3.00 D spherical equivalent (SE) progression, but this is disputed. Purpose To investigate the association between AL elongation and SE progression among children and adolescents. Methods A prospective cohort study of 710 children and adolescents aged 6–16 years was included. Ophthalmic examinations, including cycloplegic SE, AL and corneal curvature, were performed at baseline and 1‐year follow‐up. The ratio of SE change (ΔSE) to AL change (ΔAL) (ΔSE/ΔAL) was calculated, and its association with age and refractive status was explored using a general linear model. Results Among all participants, 396 (55.77%) were male, with 265 (37.32%) myopes at baseline. The average 1‐year ΔSE and ΔAL were 0.61 ± 0.40 D and 0.33 ± 0.22 mm, respectively. Both ΔSE and ΔAL gradually decreased with age (p < 0.001). In the general linear model analyses, age and refractive status were independently associated with ΔSE/ΔAL after adjustment for covariates (age: trueβ̂$$ \hat{\beta} $$ = 0.04, p < 0.05; myopia vs nonmyopia: trueβ̂$$ \hat{\beta} $$ = 0.28, p < 0.05). Based on the developed formula ΔSE/ΔAL = 1.74 + 0.05*age (for myopes), mean ΔSE/ΔAL in myopes increased from 2.06 D/mm in the 6‐year‐olds to 2.59 D/mm in the 16‐year‐olds. In nonmyopes, ΔSE/ΔAL = 1.33 + 0.05*age, and the ratio increased from 1.65 D/mm in the 6‐year‐olds to 2.18 D/mm in the 16‐year‐olds. Conclusions The ratio of ΔSE/ΔAL varied with age and refractive status in children and adolescents. The age‐specific ΔSE/ΔAL could be used to estimate SE progression through the actual AL change.

Objectives To investigate the rate of orthokeratology lens (ortho-k lens) use and its associated factors in children and adolescents with myopia. Methods Cross-sectional study. Children from 104 primary and middle schools in Shanghai were enrolled by cluster sampling. Ophthalmic examinations were conducted and information was obtained using questionnaires for associated factors analysis. Results A total of 72,920 children and adolescents were included, among which 32,259 were the potential population for ortho-k lens use. A total of 1021 participants used ortho-k lenses, equating to a use rate of 1.4% in the total population and 3.1% in the potential population. Age (OR 0.91, 95% CI: 0.88–0.95, p < 0.001), BMI (≥95th percentile: OR 0.48, 95% CI: 0.35–0.66, p < 0.001), age at initiation of refractive correction (≤12 years: OR 1.75, 95% CI: 1.31–2.33, p < 0.001), and parental myopia (either: OR 2.09, 95% CI: 1.58–2.75, p < 0.001; both: OR 3.94, 95% CI: 3.04–5.11, p < 0.001) were independently associated with ortho-k lens use. Of the ortho-k lenses users, 12.4% had a logMAR CVA of ≥0.3. A correction target (SE) of ≤−3.0 D (OR 2.05, 95% CI: 1.38–3.05, p < 0.001) and a sleeping duration of ≤6 h (OR 4.19, 95% CI: 2.03–8.64, p < 0.001) were factors independently associated with CVA ≥ 0.3. Conclusions A certain proportion of children and adolescents in Shanghai chose to wear ortho-k lenses, related to the situation of parents and children themselves. Health education and follow-ups should be strengthened to ensure orthokeratology application quality.