[The performance of visual photoscreening for Chinese preschool children aged 4 to 5 years].

Objective: To assess the accuracy of photoscreening for detecting refractive amblyopia risk factors (ARFs) in Chinese preschool children aged 4 to 5 years. Methods: A cross-sectional study. Comprehensive ocular examinations were conducted for preschool children in Nanjing, China from September to December, 2016. Photoscreening (Plusoptix A12C) was applied for refractive screening without cycloplegia. Voluntary children and children suspected of eyes abnormalities received cycloplegic retinoscopy (CR). Results of photoscreening and CR were compared using Wilcoxon signed rank test, and Bland-Altman plot were used to assess the agreement between the photoscreener and CR. According to the updated preschool vision screening guidelines from American Association for Pediatric Ophthalmology and Strabismus (AAPOS) in 2013, CR was adopted for identifying children with ARFs, which was considered as a golden standard. Based on the golden standard, the accuracy of 5 sets of referral criteria (including sensitivity standard, Matta/Silbert standard, AAPOS2013 standard, Alaska Blind Child Discovery standard, specificity standard) for photoscreener were tested. Receiver operating characteristics curves were constructed applied to evaluate the quality of the photoscreener in refractive ARFs detection and to find probably the best cut-off points. Results: In total, 1 986 children [mean age, (4.57±0.29) years] received comprehensive examinations, including 1 084 boys and 902 girls. The test ability of photoscreening was 99.04% (1 967/1 986) in the preschool children, and 96.56%(1 827/1 892) of the children got a reliable result within three screening attempts. In 538 children who had data of CR, refractive error of one child exceeded the upper limit of the photoscreener value setting, which was directly categorized as hyperopia, so in the end, 537 children were included to analyze the comparison between the two tests. The measurement values of photoscreening were lower than those of CR in sphere, cylinder and spherical equivalent [(0.75 (0.50, 1.25) D vs. 1.25 (1.00, 1.75) D, Z=-10.36, P<0.01; -0.50 (-0.75, -0.25) D vs. -0.25 (-0.75, 0.00) D, Z=-11.10, P<0.01; 0.63 (0.38, 0.88) D vs. 1.00 (0.75, 1.50) D, Z=-13.33, P<0.01]. The 95% limit of agreement cover rates between the photoscreening and CR in sphere, cylinder and spherical equivalent was 96.28% (517/537), 95.34% (512/537) and 96.65% (519/537), respectively. Based on the golden standard, 47 (8.74%) children had refractive ARFs, and the range of sensitivity, specificity, Youden index, positive predictive values and negative predictive values for detecting refractive ARFs of the 5 common used referral criteria was from 63.83% to 97.87%, from 53.36% to 97.56%, from 0.51 to 0.80, from 16.73% to 74.51% and from 96.57% to 99.62%, respectively. Considering particular refractive ARFs on the basis of the receiver operating characteristic curves, the optimal cut-off point for astigmatism was set at 1.38 D. Conclusion: Photoscreening could be an applicable tool to detect refractive ARFs in preschool children. (Chin J Ophthalmol, 2020, 56: 189-196).

[Comparision of Different Methods of Area Measurement in Irregular Scar].

OBJECTIVES: To determine a measurement standard of irregular scar area by comparing the advantages and disadvantages of different measurement methods in measuring same irregular scar area. METHODS: Irregular scar area was scanned by digital scanning and measured by coordinate reading method, AutoCAD pixel method, Photoshop lasso pixel method, Photoshop magic bar filled pixel method and Foxit PDF reading software, and some aspects of these methods such as measurement time, repeatability, whether could be recorded and whether could be traced were compared and analyzed. RESULTS: There was no significant difference in the scar areas by the measurement methods above. However, there was statistical difference in the measurement time and repeatability by one or multi performers and only Foxit PDF reading software could be traced back. CONCLUSIONS: The methods above can be used for measuring scar area, but each one has its advantages and disadvantages. It is necessary to develop new measurement software for forensic identification.

Assessing the potential for the stomatal characters of extant and fossil Ginkgo leaves to signal atmospheric CO2 change.

The stomatal density and index of fossil Ginkgo leaves (Early Jurassic to Early Cretaceous) have been investigated to test whether these plant fossils provide evidence for CO(2)-rich atmosphere in the Mesozoic. We first assessed five sources of natural variation in the stomatal density and index of extant Gingko biloba leaves: (1) timing of leaf maturation, (2) young vs. fully developed leaves, (3) short shoots vs. long shoots, (4) position in the canopy, and (5) male vs. female trees. Our analysis indicated that some significant differences in leaf stomatal density and index were evident arising from these considerations. However, this variability was considerably less than the difference in leaf stomatal density and index between modern and fossil samples, with the stomatal index of four species of Mesozoic Ginkgo (G. coriacea, G. huttoni, G. yimaensis, and G. obrutschewii) 60-40% lower than the modern values recorded in this study for extant G. biloba. Calculated as stomatal ratios (the stomatal index of the fossil leaves relative to the modern value), the values generally tracked the CO(2) variations predicted by a long-term carbon cycle model confirming the utility of this plant group to provide a reasonable measure of ancient atmospheric CO(2) change.