Clinical significance of contact lens related changes of ocular surface tissue observed on optical coherence images

PurposeTo investigate the relationship between the real contact lens imprint into the conjunctival tissue, observed by optical coherence tomography (OCT) and conjunctival staining and contact lens wearing comfort.Methods17 participants (mean age = 26.6 SD ± 3.6 years; 7 females) were fitted with three different contact lenses base curves of the same silicone hydrogel custom lens type (Visell 50; Hecht Contactlinsen, Au, Germany) in a randomised order. One lens was optimally fitted according to the manufacturer's recommendation, one fitted 0.4 mm flatter and one fitted 0.4 mm steeper. After 4 h of lens wear the contact lens edge in the area of the conjunctiva was imaged nasally and temporally using OCT (Optovue iVue SD-OCT). To correct the artefact due to optical distortion with OCT, the imprint of all worn lenses was measured on a glass plate afterwards. Conjunctival staining in the limbal region after 4 h of lens wear was classified using the CCLRU Grading Scale. Comfort scoring was based on visual analog scales from 0 (very poor) to 100 (excellent).ResultsThe mean conjunctival imprint of all contact lens edges was 32.0 ± 8.1 μm before and 7.3 ± 6.5 μm after distortion correction of the OCT images. The distortion corrected conjunctival imprint with the 0.4 mm steeper lens (11.5 ± 6.2 μm) was statistically significantly greater compared to the optimally fitted lens (6.5 ± 5.9 μm) (One-way ANOVA followed Tukey-test; p = 0.017) and greater compared to the 0.4 mm flatter lens (3.9 ± 5.3 μm) (p < 0.001). There was no statistically significant difference between the optimally fitted lens and the 0.4 mm flatter lens (p = 0.209). The nasally measured imprint (11.4 ± 9.0 μm) was significantly greater than the temporally measured (3.3 ± 7.6 μm) (p < 0.001). There was no statistically significant correlation between the amount of conjunctival imprint and the graded conjunctival staining (p = 0.346) or the wearer’s comfort (p = 0.735).ConclusionsContact lens edges imaged by OCT exhibited displacement artefacts. The observed conjunctival imprints are a combination of real conjunctival compression and artefacts. A deeper imprint of the contact lens into the conjunctiva caused by a steeper base curve was not related to clinically significant staining or changes in comfort after 4 h of lens wear. The observed differences between nasal and temporal imprint are likely to be caused by variations of conjunctival thickness and the shape of the underlying sclera.     

High Power Fiber Bundle Array Coupled LDA Module

1 Introduction High power laser diode arrays (LDA) have many advan- tages such as small volume, long working life, high slope efficiency and high optical density, so they have many applications in medical treatment, material pro- cessing, and for the pumping source of solid laser and etc. But unfortunately, the LDA can not be easy to use directly in these fields because of their poor beam quality and extremely asymmetric divergent beams (!x≈ 5°～10°and !y≈20°～35°, for example), so it …     

脉冲式半导体激光器准直光学系统的设计

根据具体的探测环境和探测精度,通过理论分析,提出了脉冲式半导体激光器准直光束的单透镜设计方法和柱面透镜的设计方法,并且给出了具体的设计参数。可以获得高斯光束的准直发散角为1.48mrad;高斯光束的腰粗为0.325mm。     

一种微透镜阵列的研制

介绍一种利用表面张力的作用、以光纤作材料、用分离的自聚焦透镜制作微透镜阵型的方法，这种方法具有制作工艺简单、无须昂贵设备等优点，用此方法实际制作了具有良好连续面型的微透镜阵列，并对制作的微透镜阵列进行了测试，效果较好。     

带像差补偿的光盘像散自动调焦透镜设计

对光盘光学头检测光路中广泛使用的光学平板所引入的光学像差进行分析计算,并由 此设计了一种放置于光盘光学头检测光路中的用以产生聚焦误差信号的像散透镜。它不但可以产生正常的调焦误差信号,同时还可以补偿由斜放入检测光路中的光学平板所带来的光学像差。经过实际应用,证明这种结构完全能够满足高密度光盘光学头的技术要求。     

Thermal-lens and photo-acoustic methods for the determination of SiC thermal properties

In this paper we report the use of photothermal techniques such as Thermal lens (TL) spectrometry, Photoacoustic and heat capacity, ρc_p, to determine the thermo-optical parameters, such as thermal conductivity (K), thermal diffusivity (D), specific heat (c_p) and the optical path dependence with temperature (ds/dT), of an undoped polycrystalline 3C-SiC. To our knowledge, this is the first time that Thermal lens technique is used for wide band-gap systems. Results obtained for the polycrystalline sample with TL technique indicates that ds/dT is negative at room temperature. Moreover, the obtained values of thermal diffusivity and thermal conductivity are in good agreement with that found in the literature, indicating that the phototermal techniques can be used to obtain the referred parameters in circumstances where other techniques cannot be used, for example, in harsh environments.     

点状屏彩色显示管校正透镜优化设计

本文在条状屏彩色显象管校正透镜设计的基础上，提出了蹼状屏彩色显示管校正透镜的优化设计方法并给出了设计实例，通过计算机模拟电子束轨迹和光线追迹，分析了校正透镜面型修正程序的精度。     

用单透镜变换由多模光纤出射的大功率Nd：YAG激光束的特性

根据理论假设，通过选取单透镜的参数和位置，计算说明了单透镜使经由多模光纤出射的大功率Ｎｄ：ＹＡＧ激光束的发射角压缩，光束聚焦效率提高，光束截面场为高斯分布；文中的计算结果符合已知规律，从而说明了理论假设的正确性。     

高分辨率显示屏特性分析用光学透镜设计

描述了高分率显示屏特性分析用的光学透镜的特点和设计要求。分析了调焦镜头和镜头位置调节两种结构的优缺点，推导了屏厚变化（即物距变化）对测量精度影响的表达式。给出了设计实例。实验测量结果与理论分析基本上一致。