Oral omega-6 essential fatty acid treatment in contact lens associated dry eye

PURPOSE: Symptoms of dry eye are commonly reported in contact lens wearers and are a frequent cause of non-tolerance. The purpose of the present study is to evaluate the effects of oral treatment with particular omega-6 fatty acids in the form of evening primrose oil (EPO) on subjective symptoms, ocular surface signs and tear film characteristic in patients with contact lens associated dry eye. METHODS: The study design was randomised, double-masked and placebo controlled. 76 female soft contact lens wearers were treated for 6 months with either EPO or placebo (olive oil). Subjects underwent three examinations (baseline, 3 and 6 months). At each examination subjects were given a questionnaire relating to lens comfort and dry eye symptoms and underwent a series of tests of tear film characteristics (tear meniscus height, break-up time), meibomian gland function (lipid layer thickness and quality) and ocular surface parameters (hyperaemia and staining). RESULTS: The EPO group showed a significant improvement in the specific symptom of 'dryness' at 3 and 6 months (p<0.01) and also a significant improvement in overall lens comfort at 6 months (p<0.01). Tear meniscus height was increased in the EPO group at 6 months relative to baseline (p<0.01), although all other objective signs were unchanged. CONCLUSION: This study provides evidence for a beneficial effect of particular orally administered omega-6 fatty acids in alleviating dry eye symptoms and improving overall lens comfort in patients suffering from contact lens associated dry eye.     

The effect of lens wear on refractive index of conventional hydrogel and silicone-hydrogel contact lenses: a comparative study.

PURPOSE: The purpose of this work was to evaluate the ability of four silicone-hydrogel contact lenses (galyfilcon A, balafilcon A, lotrafilcon A and lotrafilcon B) to retain their equilibrium water content before and after wear, through measurements of refractive index and compare with that of a conventional disposable hydrogel contact lens (etafilcon A). METHODS: The refractive indices of 115 contact lenses were measured using an automated refractometer (CLR 12-70, Index Instruments, Cambridge, U.K.) before and after a schedule of daily wear by 58 patients for 30 days in the case of silicone-hydrogel lenses and 15 days for the conventional contact lenses. RESULTS: In the silicone-hydrogel contact lenses the changes on the refractive indices were not statistically significant, however after being worn the refractive index of the conventional etalfilcon A hydrogel contact lens increased significantly (p<0.001). CONCLUSION: The results presented here show that after being worn the silicone-hydrogel contact lens, show more capacity to retain or to reach their initial equilibrium water content than conventional hydrogel contact lenses. This suggests that the silicone-hydrogel contact lenses are less susceptible to spoilation over time maintaining its biocompatibility and contributing to the clinical success of lens performance.     

柑桔贮藏期纳米二氧化钛抑制霉菌性能研究

用液相沉积法对纳米二氧化钛进行包覆改性并研究柑桔贮藏期其抑制霉菌的性能,并用牛津杯法研究其抗菌性能,探讨了改性前后抗菌性能的变化.结果表明TiO2表面包覆SiO2可有效防止团聚的发生,改善在水溶液中的分散稳定性;抑菌实验表明,当p(SiO2-TiO2)=0.1g/L,对桔青霉、黑曲霉的抑菌圈直径分别达14、16mm,显出了优异的抗菌性能.     

一种盘式电机铁心自动成形方法

对盘式电机定子和转子铁心成形工艺特点进行了研究．提出冲槽模移动的送料补偿成形系统及补偿方法。讨论了不同下线槽倾角γ的铁心成形方法     

Visual quality with corneo-scleral contact lenses after intracorneal ring segment (ICRS) implantation for keratoconus management

PurposeTo evaluate the visual quality results when fitting a corneo-scleral contact lens (CScL) after intracorneal ring segment (ICRS) implantation for keratoconus management.MethodsTwenty-seven eyes of 27 patients with keratoconus underwent ICRS implantation and had CScL fitted as their visual quality was unsatisfactory with their spectacles or contact lenses. Patients received a complete eye examination, refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count, and visual quality assessment using contrast sensitivity and aberrometry tests. A diagnostic trial set was used in the fitting process, and patients were assessed according to a standardised methodology, including subjective visual quality and comfort, and contact lens usage time. The follow-up period was one year.ResultsAfter fitting CScL, log-MAR visual acuity values improved significantly in relation to the best spectacle-corrected vision (0.22 ± 0.17 vs 0.00 ± 0.12; p < 0.001). Total high-order aberrations decreased 33% (2.62 ± 1.31 vs 1.75 ± 1.81 μm; p < 0.009) and the spatial frequencies of contrast sensitivity all improved (all p < 0.05). Furthermore, 70.37% of patients reported high ratings of subjective visual quality (favourable and very favourable) and prolonged usage times (11.78 ± 3.93 h). After wearing CScL for one year, no adverse ocular effects or clinically relevant changes in corneal parameters, visual quality, comfort ratings or usage time were found.ConclusionThis CScL appears to be an alternative reasonable option for keratoconic eyes with ICRS placement, providing an improvement in subjective visual quality.     

Anterior eye surface changes following miniscleral contact lens wear

PurposeTo quantify the effect of short-term miniscleral contact lens wear on the anterior eye surface of healthy eyes, including cornea, corneo-scleral junction and sclero-conjuctival area.MethodsTwelve healthy subjects (29.9 ± 5.7 years) wore a highly gas-permeable miniscleral contact lens of 16.5 mm diameter during a 5-hour period. Corneo-scleral height profilometry was captured before, immediately following lens removal and 3 h after lens removal. Topography based corneo-scleral limbal radius estimates were derived from height measurements. In addition, elevation differences in corneal and scleral region were calculated with custom-written software. Sclero-conjuctival flattening within different sectors was analysed.ResultsShort-term miniscleral lens wear significantly modifies the anterior eye surface. Significant limbal radius increment (mean ± standard deviation) of 146 ± 80 μm, (p = 0.004) and flattening of −122 ± 90 μm in the sclero-conjuctival area, (p << 0.001) were observed immediately following lens removal. These changes did not recede to baseline levels 3 h after lens removal. The greatest anterior eye surface flattening was observed in the superior sector. No statistically significant corneal shape change was observed immediately following lens removal or during the recovery period.ConclusionsShort-term miniscleral contact lens wear in healthy eyes does not produce significant corneal shape changes measured with profilometry but alters sclero-conjuctival topography. In addition, sclero-conjuctival flattening was not uniformly distributed across the anterior eye.     

A topographical method to quantify scleral contact lens decentration

PurposeTo describe a simple method to quantify scleral contact lens decentration using over-topography captured with a Placido ring videokeratoscope, and its repeatability.MethodsScleral lens over-topography (E300 videokeratoscope, Medmont) was measured on 10 healthy participants following 15 min of lens settling (16.5 mm total diameter ICD miniscleral, Capricornia). Horizontal and vertical lens decentration was quantified from the translation of the front optic zone relative to the pupil centre derived from ellipses manually fitted to tangential power over-topography maps using both a standard and normalised dioptric scale. Intrasession (different maps captured within the same measurement session), intraobserver (identical maps analysed by the same observer), and intertechqniue (standard or normalised tangential power scales) repeatability were calculated.ResultsThe mean lens decentration was 0.62 ± 0.18 mm temporally and 0.91 ± 0.33 mm inferiorly. Lens decentration derived from tangential topography maps with a standard power scale were more repeatable (95% limits of agreement for intraobserver repeatability ± 0.07 mm and intrasession repeatability ± 0.15 mm) than measurements derived from normalised maps (95% limits of agreement for intraobserver repeatability ± 0.11 mm and intrasession repeatability ± 0.20 mm).ConclusionsScleral lens decentration can be reliably quantified using tangential power maps with a standard (fixed) scale captured during over-topography without the need for customised instrumentation or image analysis software. This method has a range of potential applications in research and clinical practice.     

右前门外拉手盖注射模具设计

分析右前门外拉手盖的结构工艺性,介绍该注射模具关键机构的技术要点及设计思路。根据产品结构设计出模具的浇注系统、成形零件、顶出机构、侧抽芯机构以及冷却系统,特别是采用二级滑块抽芯机构合理地解决斜孔成型与抽芯的工艺难题。结果表明,该模具结构紧凑,动作可靠,可为类似结构的注射模具提供借鉴。     

电渣重熔过程结晶器旋转对钢中夹杂物的影响

基于自行设计的双极串联结晶器旋转电渣重熔炉,采用ASPEX全自动夹杂物分析仪研究了结晶器转速对M2电渣锭洁净度的影响。结果表明,不论结晶器是否旋转,电渣锭中的夹杂物组成基本不变,主要由Al2O3, Al2O3–MnS, Al2O3–SiO2–CaO–MnS, MgO–Al2O3–SiO2–CaO–MnO, MgO–Al2O3–SiO2–CaO–TiO2–MnS, Al2O3–SiO2–CaO–MnO–TiO2组成,其中以Al2O3, Al2O3–SiO2–CaO–MnO–TiO2和Al2O3–MnS数量最多。结晶器静止电渣重熔时,钢中的夹杂物数量较多,且存在50 ?m以上的大颗粒夹杂物,而结晶器转速为6和13 r/min时,夹杂物数量减少,大颗粒夹杂含量大大降低;转速增至19 r/min时,夹杂物数量及尺寸又进一步增加,同时钢中全氧含量、氮含量明显增加。电渣锭中大颗粒夹杂物得以去除的主要原因是结晶器旋转导致金属自耗电极末端的熔融层变薄、熔滴尺寸变小,渣–金接触面积增大,促进了夹杂物被熔渣去除;过快的转速会增加自耗电极氧化、减少渣–金接触时间,从而降低电渣重熔过程的精炼能力。     

大面积发散太阳模拟器均匀照明方法研究

为实现太阳模拟器的大辐照面积均匀照明,研究了大面积发散太阳模拟器光学系统的设计与仿真。分析了复眼透镜阵列组与发散投影系统工作原理及旁瓣效应产生机理;基于嵌套建模思想,结合多项式拟合方法,得出了氙灯轴上强度分布曲线,并根据氙灯发光能量对称性质,实现了氙灯空间光强分布模拟;结合提出的光学系统设计边界条件与参数,设计了光束整形系统、复眼透镜阵列组和发散投影系统。实验结果表明：当工作距离为20000mm,辐照面直径1500mm范围内,辐照均匀度为92.8%,满足了大面积发散太阳模拟器均匀照明的使用需求。