Assessment of intraocular pressure measured by Reichert Ocular Response Analyzer,Goldmann Applanation Tonometry,and Dynamic Contour Tonometry in healthy individuals

AIM: To investigate the accuracy of intraocular pressure (IOP) as measured by a Reichert Ocular Response Analyzer (ORA), as well as the relationship between central corneal thickness (CCT) and IOP as measured by ORA, Goldmann applanation tonometry (GAD, and dynamic contour tonometry (DCT). METHODS: A total of 158 healthy individuals (296 eyes) were chosen randomly for measurement of IOP. After CCT was measured using A-ultrasound (A-US), IOP was measured by ORA, GAT, and DCT devices in a randomized order. The IOP values acquired using each of the three tonometries were compared, and the relationship between CCT and IOP values were analyzed separately. Two IOP values, Goldmann-correlated IOP value (IOPg) and corneal-compensated intraocular pressure (IOPcc), were got using ORA. Three groups were defined according to CCT: 1) thin cornea (CCT<520 mu m); 2) normal-thickness cornea (CCT: 520-580 mu m); and 3), thick cornea (CCT>580 mu m) groups. RESULTS: In normal subjects, IOP measurements were 14.95 2.99mmHg with ORA (IOPg), 15.21+/- 2.77mmHg with ORA(IOPcc),1522+/- 2.77mmHg with GAT,and 15.49+/- 2.56mmHg with DCT. Mean differences were 0.01+/- 2.29mmHg between IOPcc and GAT (P >0.05) and 0.28+/- 2.20mmHg between IOPcc and DC (P >0.05). There was a greater correlation between IOPcc and DCT (r =0.946, P =0.000) than that between IOPcc and GAT (r=0.845, P=0.000). DCT had a significant correlation with GAT (r=0.854, P=0.000). GAT was moderately correlated with CCT (r=0.296, P<0.001), while IOPcc showed a weak but significant correlation with CCT (r =0.155, P =0.007). There was a strong negative correlation between CCT and the difference between IOPcc and GAT (r=-0.803, P=0.000), with every 10 m increase in CCT resulting in an increase in this difference of 0.35mmHg. The thick cornea group (CCT>580 mu m) showed the least significant correlation between IOPcc and GAT (r=0.859, 0.000); while the thin cornea group (CCT< 520 mu m) had the most significant correlation between IOPcc and GAT (r= 0.926, P =0.000). The correlated differences between IOPcc and DCT were not significant in any of the three groups (P>0.05). CONCLUSION: Measurement of IOP by ORA has high repeatability and is largely consistent with GAT measurements. Moreover, the ORA measurements are affected only to a small extent by CCT, and are likely to be much closer to the real IOP value than GAT.

Dispersion and Filler Network Structure of Fibrillar Silicates in Elastomers

The dispersion and filler network of fibrillar silicate（FS） in elastomers were studied. The results showed that a good dispersion of FS in matrix during mechanical blending in unvulcanized composites contributed to a strong FS filler network, different from that of traditional reinforcing fillers. Meanwhile, the filler re-aggregation during vulcanization caused by the overlapping and intertwining of FS further strengthened the filler network. The factors including Mooney viscosity and molecular polarity of elastomer, type and amount of silane coupling agents used for filler modification, that may influence the filler network, were studied. Our study helps us to understand the mechanism for the formation of filler network of FS in elastomers and provides guidance for the preparation of high performance FS/elastomer composites.