Comparison of anti-inflammatory effects of intense pulsed light with tobramycin/dexamethasone plus warm compress on dry eye associated meibomian gland dysfunction

AIM: To compare the anti-inflammatory effects of intense pulsed light(IPL) with tobramycin/dexamethasone plus warm compress through clinical signs and cytokines in tears.METHODS: Eighty-two patients with dry eye disease(DED) associated meibomian gland dysfunction(MGD) were divided into two groups. Group A was treated with IPL, and Group B was treated with tobramycin/dexamethasone plus warm compress. Ocular Surface Disease Index(OSDI), tear film breakup time(TBUT), corneal fluorescein staining(CFS), meibomian gland expressibility(MGE), meibum quality, gland dropout and tear cytokine levels were evaluated before treatment, 1 wk and 1 mo after treatment. RESULTS: TBUT in Group A was higher(P=0.035), and MGE score was lower than Group B at 1 mo(P=0.001). The changes of interleukin(IL)-17 A and IL-1β levels in tears were lower in Group A compared with that in Group B at 1 wk after treatment(P=0.05, P=0.005).CONCLUSION: Treatment with IPL can improve TBUT and MGE and downregulate levels of IL-17 A and IL-1β in tears of patients with DED associated MGD better than treatment with tobramycin/dexamethasone plus warm compress in one-month treatment period.

Evaluations of wavefront aberrations and corneal surface regularity in dry eye patients measured with OPD Scan Ⅲ

AIM: To compare the wavefront aberrations and corneal surface regularity between dry eye(DE) patients and normal subjects and assess its diagnostic performance for DE measured with OPD Scan-Ⅲ.METHODS: Fifty right eyes of 50 DE patients and 31 right eyes of normal subjects were included.The examinations for ocular surface including logarithm of the minimum angle of resolution best-corrected distance visual acuity(logMAR BCVA) the ocular surface disease index(OSDI), tear film break-up time(TBUT) and corneal fluorescein staining(CFS).OPD Scan-Ⅲ was used to measure anterior corneal aberrations including total corneal aberrations, high order aberration(HOA), coma, trefoil, spherical aberration(SA), standard deviation of corneal power(SDP), surface regularity index(SRI) and surface asymmetry index(SAI).Statistical analysis were assessed with nonparametric tests and Spearman’s correlations.All parameters were also analyzed for sensitivity, specificity, and receiver operating characteristics(ROC) curves.RESULTS: Wavefront aberrations parameters including total corneal aberrations, HOA, coma, trefoil, and SA in DE group were significantly higher than those in normal group(P<0.001).Corneal surface regularity parameters including SRI and SAI in DE group were significantly higher than both in normal group(P<0.05).All the wavefront aberrations parameters had significant correlations with ocular surface parameters(P<0.05).The logMAR BCVA had positive correlations with SAI and SRI(all P<0.001).CFS scores had positive correlations with SAI and SRI(all P<0.001).All the wavefront aberrations parameters showed good diagnosis sensitivity and specificity, however, the corneal regularity parameters showed only good specificity but poor sensitivity.The cut-off value selected for trefoil in diagnosis DE showed the highest area under the curve(AUC, 0.921) values as compared to the other parameters with sensitivity of 0.955 and specificity of 0.867.CONCLUSION: Wavefront aberrations and corneal surface regularity are increased in DE patients and also correlated with ocular surface parameters.Wavefront aberrations parameters have potential to be indicators to diagnosis and monitor DE.

Graphite addition for SiC formation in diamond/SiC/Si composite preparation

Herein, graphite was used in the Si-vapor reactive infiltration of diamond/SiC/Si composites to produce composites with various Si C contents. X-ray diffraction was used to determine the phases of the composite, whereas scanning electron microscopy was used to confirm the Si–C reaction between the silicon, graphite, and diamond and to observe the SiC morphology. Various SiC contents in the composite were observed with graphite addition. Furthermore, the reaction between silicon and graphite(diamond) produced coarse(fine) SiC particles. The generation of a 10-μm-diameter Si–C area on the surface of the diamond was observed. The thermal conductivity(TC) and coefficient of thermal expansion(CTE) of the composite was investigated, where the TC varied from 317–426 W·m^-1·K^-1 with the increase of the SiC volume fraction from 38% to 76% and the corresponding CTE increased from 1.7 × 10^-6 to 3.7 × 10^-6 K^-1, respectively. Furthermore, a critical point for the CTE was found to exist at approximately 250℃, where the composite was under a hydrostatic condition. Finally, the bending strength was found to range from 241 to 341 MPa.

Microstructure and graphitization behavior of diamond/SiC composites fabricated by vacuum vapor reactive infiltration

To inhibit the graphitization of diamond under high temperature and low pressure, diamond/SiC composites were firstly fabricated by a rapid gaseous Si vacuum reactive infiltration process. The microstructure and graphitization behavior of diamond in the composites under various infiltration temperatures and holding time were investigated. The thermal conductivity of the resul- tant materials was discussed. The results show that the diamond-to-graphite transition is effectively inhibited at temperature of as high as 1600 ℃ under vacuum, and the substantial graphitization starts at 1700 ℃. The microstructure of those ungraphitized samples is uniform and fully densified. The inhibition mechanisms of graphitization include the isolation of the catalysts from diamond by a series of protective layers, high pressure stress applied on diamond by the reaction-bonded SiC, and the moderate gas-solid reaction. For the graphitized samples, the boundary between diamond and SiC is coarse and loose. The graphitization mechanism is considered to be an initial detachment of the bilayers from the diamond surfaces, and subsequently flattening to form graphite. The ungraphitized samples present higher thermal conductivity of about 410 W.m-1.K-1 due to the fine interfacial structure. For the graphitized samples, the thermal conductivity decreases significantly to 285 W.m-1.K-1 as a result of high interfacial thermal resistance.