In vivo human crystalline lens topography

Custom high-resolution high-speed anterior segment spectral domain optical coherence tomography (OCT) was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo. The system was provided with custom algorithms for denoising and segmentation of the images, as well as for fan (scanning) and optical (refraction) distortion correction, to provide fully quantitative images of the anterior and posterior crystalline lens surfaces. The method was tested on an artificial eye with known surfaces geometry and on a human lens in vitro, and demonstrated on three human lenses in vivo. Not correcting for distortion overestimated the anterior lens radius by 25% and the posterior lens radius by more than 65%. In vivo lens surfaces were fitted by biconicoids and Zernike polynomials after distortion correction. The anterior lens radii of curvature ranged from 10.27 to 14.14 mm, and the posterior lens radii of curvature ranged from 6.12 to 7.54 mm. Surface asphericities ranged from −0.04 to −1.96. The lens surfaces were well fitted by quadrics (with variation smaller than 2%, for 5-mm pupils), with low amounts of high order terms. Surface lens astigmatism was significant, with the anterior lens typically showing horizontal astigmatism (Z22 ranging from −11 to −1 µm) and the posterior lens showing vertical astigmatism (Z22 ranging from 6 to 10 µm).OCIS codes: (110.4500) Optical coherence tomography, (120.6650) Surface measurements, figure, (120.4640) Optical instruments, (120.4800) Optical standards and testing, (110.6880) Three-dimensional image acquisition, (330.7327) Visual optics, ophthalmic instrumentation     

Eye motion correction algorithm for OCT-based corneal topography

With its sequential image acquisition, OCT-based corneal topography is often susceptible to measurement errors due to eye motion. We have developed a novel algorithm to detect eye motion and minimize its impact on OCT topography maps. We applied the eye motion correction algorithm to corneal topographic scans acquired using a 70 kHz spectral-domain OCT device. OCT corneal topographic measurements were compared to those from a rotating Scheimpflug camera topographer. The motion correction algorithm provided a 2-4 fold improvement in the repeatability of OCT topography and its agreement with the standard Scheimpflug topographer. The repeatability of OCT Zernike-based corneal mean power, cardinal astigmatism, and oblique astigmatism after motion detection was 0.14 D, 0.28 D, and 0.24 D, respectively. The average differences between the two devices were 0.19 D for simulated keratometry-based corneal mean power, 0.23 D for cardinal astigmatism, and 0.25 D for oblique astigmatism. Our eye motion detection method can be applied to any OCT device, and it therefore represents a powerful tool for improving OCT topography.     

Quantitative OCT-based corneal topography in keratoconus with intracorneal ring segments

Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) was used to characterize three-dimensionally (3-D) corneal topography in keratoconus before and after implantation of intracorneal ring segments (ICRS). Previously described acquisition protocols were followed to minimize the impact of the motions of the eye. The collected set of images was corrected from distortions: fan (scanning) and optical (refraction). Custom algorithms were developed for automatic detection and classification of volumes in the anterior segment of the eye, in particular for the detection and classification of the implanted ICRS. Surfaces were automatically detected for quantitative analysis of the corneal elevation maps (fitted by biconicoids and Zernike polynomials) and pachymetry. Automatic tools were developed for the estimation of the 3-D positioning of the ICRS. The pupil center reference was estimated from the segmented iris volume. The developed algorithms are illustrated in a keratoconic eye (grade III) pre- and 30 days post-operatively after implantation of two triangular-section, 0.3-mm thick Ferrara ring segments. Quantitative corneal topographies reveal that the ICRS produced a flattening of the anterior surface, a steepening of the posterior surface, meridional differences in the changes in curvature and asphericity, and increased symmetry of the anterior topography. Optical distortion correction through the ICRS (of a different refractive index from the cornea) allowed accurate pachymetric estimates, which showed increased thickness in the ectatic area as well as in peripheral corneal areas. Automatic tools allowed estimation of the depth of the implanted ICRS ring, as well as its rotation with respect to the pupil plane. Anterior segment sOCT provided with fan and optical distortion correction and analysis tools is an excellent instrument for evaluating and monitoring keratoconic eyes and for the quantification of the changes produced by ICRS treatment.     

A model for crystalline lens accommodation

When a slight equatorial pull is applied to the crystalline lens, the center thickens, the central surfaces steepen, and the optical power increases. These findings are consistent with Schachar's theory of accommodation. The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article. The authors also do not discuss the use of off-label products, which includes unlabeled, unapproved, or investigative products or devices.     

晶状体疾病的超声检查

目的 探讨晶状体疾病超声检查的临床意义.方法 应用彩色多普勒超声检测821只患眼的晶状体病变情况,并分析其声像图特点.结果 超声诊断白内障748只眼,晶状体脱位30只眼,晶状体破裂8只眼;合并各类眼内病479只眼,占58.3%(479/8 21).结论 超声能准确诊断晶状体疾病,并对眼内伴随疾病作出定性诊断,对手术方式的选择和评价术后效果有重要的临床意义.     

OCT 3-D surface topography of isolated human crystalline lenses

Quantitative 3-D Optical Coherence Tomography was used to measure surface topography of 36 isolated human lenses, and to evaluate the relationship between anterior and posterior lens surface shape and their changes with age. All lens surfaces were fitted to 6th order Zernike polynomials. Astigmatism was the predominant surface aberration in anterior and posterior lens surfaces (accounting for ~55% and ~63% of the variance respectively), followed by spherical terms, coma, trefoil and tetrafoil. The amount of anterior and posterior surface astigmatism did not vary significantly with age. The relative angle between anterior and posterior surface astigmatism axes was on average 36.5 deg, tended to decrease with age, and was >45 deg in 36.1% lenses. The anterior surface RMS spherical term, RMS coma and 3rd order RMS decreased significantly with age. In general, there was a statistically significant correlation between the 3rd and 4th order terms of the anterior and posterior surfaces. Understanding the coordination of anterior and posterior lens surface geometries and their topographical changes with age sheds light into the role of the lens in the optical properties of the eye and the lens aging mechanism.OCIS codes: (110.4500) Optical coherence tomography, (100.2960) Image analysis, (200.4560) Optical data processing     

胶原性眼内接触镜眼内植入后的生物相容性评价

背景：有晶体眼后房型人工晶体（又称眼内接触镜）植入术是近年来兴起的一种矫治高度近视的晶体屈光性手术：Start公司将Ⅳ型胶原与水凝胶聚合而成的新型材料Collamer．是研制眼内接触镜的理想材料．但国外产品价格昂贵，一定程度上限制了该手术的开展. 目的：通过兔眼动物实验摸索理想的胶原性眼内接触镜植入方法．观察眼内接触镜植入术后炎症反应和炎症递质的变化、并对其植入眼内的生物相容性进行评价。 设计：单一样本，开放性实验. 单位：上海交通大学医学院附属新华医院眼科 材料：实验于1999—08／2000—03在上海交通大学医学院附属新华医院和上海南洋放射免疫测试中心完成。选取成年新西兰纯种白兔20只，随机数字表法分为3组：眼内接触镜植入组8只，手术对照组6只、空白对照组6只。 方法：①眼内接触镜植入组右眼行眼内接触镜植入＋虹膜剧切术，手术对照组右眼单纯行虹膜周切术．手术由专人按同一方式施行。术后两组术眼滴用激素抗菌素眼药水．4次／d．共10d均于术后1，4．7d结膜下注射地塞米松2．5mg＋庆大霉素4万U。空白对照组不进行手术。②分别于术后1．4，7．14d和1个月对眼内接触镜植入组、手术对照组的术眼进行眼压波动、角膜损伤、前房蛋白细胞渗出、前房深度、前房出血、虹膜后粘连．服内接触镜偏位以及晶体混浊等监测。③分别于术后1，4，7．14d和1个月对眼内接触镜植入组、手术对照组的术眼进行房水取样．空白对照组也在相应时间取样，采用放射免疫分析法测定前列腺素E2浓度。 主要观察指标：①术前及术后各时间点前房反应检测结果。②术后各组房水中炎症递质前列腺素E2浓度检测结果。 结果：实验选取新西兰纯种白兔20只．全部进入结果分析。①术前及术后各时间点眼压的变?     

胶原性眼内接触镜眼内植入后的生物相容性评价

背景:有晶体眼后房型人工晶体(又称眼内接触镜)植入术是近年来兴起的一种矫治高度近视的晶体屈光性手术。Starr公司将IV型胶原与水凝胶聚合而成的新型材料Collamer,是研制眼内接触镜的理想材料,但国外产品价格昂贵,一定程度上限制了该手术的开展。目的:通过兔眼动物实验摸索理想的胶原性眼内接触镜植入方法,观察眼内接触镜植入术后炎症反应和炎症递质的变化,并对其植入眼内的生物相容性进行评价。设计:单一样本,开放性实验。单位:上海交通大学医学院附属新华医院眼科。材料:实验于1999-08/2000-03在上海交通大学医学院附属新华医院和上海南洋放射免疫测试中心完成。选取成年新西兰纯种白兔20只,随机数字表法分为3组:眼内接触镜植入组8只、手术对照组6只、空白对照组6只。方法:①眼内接触镜植入组右眼行眼内接触镜植入 虹膜周切术,手术对照组右眼单纯行虹膜周切术,手术由专人按同一方式施行。术后两组术眼滴用激素抗菌素眼药水,4次/d,共10d。均于术后1,4,7d结膜下注射地塞米松2.5mg 庆大霉素4万U。空白对照组不进行手术。②分别于术后1,4,7,14d和1个月对眼内接触镜植入组、手术对照组的术眼进行眼压波动、角膜损伤、前房蛋白细胞渗出、前房深度、前房出血、虹膜后粘连、眼内接触镜偏位以及晶体混浊等监测。③分别于术后1,4,7,14d和1个月对眼内接触镜植入组、手术对照组的术眼进行房水取样,空白对照组也在相应时间取样,采用放射免疫分析法测定前列腺素E2浓度。主要观察指标:①术前及术后各时间点前房反应检测结果。②术后各组房水中炎症递质前列腺素E2浓度检测结果。结果:实验选取新西兰纯种白兔20只,全部进入结果分析。①术前及术后各时间点眼压的变化:与术前比较,眼内接触镜植入组、手术对照组术后各时间点眼压均无明显变化(P>0.05)。②术后角膜损伤和前房渗出情况:眼内接触镜植入组:5只兔眼术后第1天出现不同程度的前房变浅,1周内均恢复正常;2只兔眼出现少量前房出血,2周后吸收;2只兔眼分别出现虹膜前粘连和后粘连,瞳孔轻度变形;2只兔眼出现不同程度眼内接触镜偏位;1只兔眼术后1个月出现晶体前囊膜下点状混浊。手术对照组:6只兔眼术后第1天前房出现1～2级渗出,1周后均吸收;各兔眼角膜透明,无前房出血、前房变浅、虹膜后粘、晶体混浊等变化。③术后各组房水中炎症递质前列腺素E2浓度检测结果:眼内接触镜植入组术后1～4d房水中前列腺素E2含量最高,以后含量逐步递减。术后14d和1个月,各组均基本相似(P>0.05)。结论:眼内接触镜植入术后前房无明显慢性葡萄膜炎发生。房水中前列腺素E2浓度逐步降低,表现了眼内接触镜植入后典型的异物肉芽肿炎症过程,反映其良好的眼内耐受性。     

A mathematical expression for the human crystalline lens

A mathematical representation of the human crystalline lens is proposed. It is expressed in a parametric form, which is confirmed when tested against five independently published MRI images. Analytical functions for capsule thickness were also developed. The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer or provider of services discussed in this article.     

Straylight,lens yellowing and aberrations of eyes in Type 1 diabetes

Straylight, lens yellowing and ocular aberrations were assessed in a group of people with type 1 diabetes and in an age matched control group. Most of the former had low levels of neuropathy. Relative to the control group, the type 1 diabetes group demonstrated greater straylight, greater lens yellowing, and differences in some higher-order aberration co-efficients without significant increase in root-mean-square higher-order aberrations. Differences between groups did not increase significantly with age. The results are similar to the findings for ocular biometry reported previously for this group of participants, and suggest that age-related changes in the optics of the eyes of people with well-controlled diabetes need not be accelerated.OCIS codes: (330.4875) Optics of physiological systems, (330.7329) Visual optics, pathology     

胶原性眼内接触镜兔眼植入术后的生物相容性研究

背景有晶体眼眼内接触镜植入术是一种矫治高度近视的新型手术,胶原作为一种新型材料已在国外应用于眼内接触镜(ICL)的研制,国内尚无同类产品.目的通过兔眼的动物实验,观察胶原性眼内接触镜植入眼内后的组织细胞学反应,评定胶原的生物相容性.设计随机对照成组实验设计.地点和对象本研究在上海第二医科大学附属新华医院眼科完成,实验对象为 20只新西兰白兔,体质量 2.0～ 2.5 kg,性别不分.干预实验兔随机分为 ICL植入组、手术对照组和空白对照组 3组.术后 14 d和 28 d,取下实验动物眼的前段组织和 ICL.采用苏木精-伊红染色光镜检查及透射、扫描电镜技术进行观察摄片.主要观察指标 ICL表面和眼前段组织细胞形态学观察.结果 ICL植入组术后早期眼前段组织中以大量吞噬细胞浸润为主,巨噬细胞功能活跃,成纤维细胞较少.后期巨噬细胞数量减少,成纤维细胞增多.手术对照组术后早期眼前段组织中较多巨噬细胞存在,后期成纤维细胞显著增多,且有纤维组织形成.结论 ICL植入术后炎症细胞变化情况显示为典型的异物肉芽肿性炎症过程.胶原性 ICL具有优良的眼内生物相容性.     

Increased crystalline lens coverage in optical coherence tomography with oblique scanning and volume stitching

A three-dimensional optical coherence tomography (OCT) crystalline lens imaging method based on oblique scanning and image stitching is presented. The method was designed to increase OCT imaging volume of crystalline lens in vivo. A long-range swept-source (SS)-OCT imaging system, which can measure the entire anterior segment of eye in a single acquisition, is used to acquire one central volume and 4 extra volumes with different angles between optical axis of OCT instrument and the pupillary axis. The volumes are then stitched automatically by developed software. To show its effectiveness and verify its validity, we scanned the subjects before and after pupil dilation drops and compared the experimental results. By determining the number of voxels representing the signal from the crystalline lens in 3-D OCT images, our method can provide around 17% additional volumetric lens coverage compared with a regular imaging procedure. The proposed approach could be used clinically in early diagnosis of cortical cataract. Wider field of view offered by this method may facilitate more accurate lens biometry in its peripheral zones, which potentially contributes to understanding of lens shape modifications of the accommodating eye.     

Age-dependence of the average and equivalent refractive indices of the crystalline lens

Lens average and equivalent refractive indices are required for purposes such as lens thickness estimation and optical modeling. We modeled the refractive index gradient as a power function of the normalized distance from lens center. Average index along the lens axis was estimated by integration. Equivalent index was estimated by raytracing through a model eye to establish ocular refraction, and then backward raytracing to determine the constant refractive index yielding the same refraction. Assuming center and edge indices remained constant with age, at 1.415 and 1.37 respectively, average axial refractive index increased (1.408 to 1.411) and equivalent index decreased (1.425 to 1.420) with age increase from 20 to 70 years. These values agree well with experimental estimates based on different techniques, although the latter show considerable scatter. The simple model of index gradient gives reasonable estimates of average and equivalent lens indices, although refinements in modeling and measurements are required.OCIS codes: (330.4460) Ophthalmic optics and devices, (330.7326) Visual optics, modeling     

Calculation of crystalline lens power using a modification of the Bennett method

We present a method for measuring lens power from extended depth OCT biometry, corneal topography, and refraction using an improvement on the Bennett method. A reduced eye model was used to derive a formula for lens power in terms of ocular distances, corneal power, and objective spherical equivalent refraction. An error analysis shows that the formula predicts relaxed lens power with a theoretical accuracy of ± 0.5 D for refractive error ranging from −10 D to + 10 D. The formula was used to calculate lens power in 16 eyes of 8 human subjects. Mean lens power was 24.3 D ± 1.7 D.OCIS codes: (170.4500) Optical coherence tomography, (170.4580) Optical diagnostics for medicine, (330.7325) Visual optics, metrology, (330.7326) Visual optics, modeling     

小切口非超声乳化手法碎核白内障摘除人工晶体植入术570例临床分析

目的探讨在基层防盲治盲中小切口非超声乳化手法碎核白内障摘除人工晶体植入术临床效果。方法对570例570眼白内障,在表面麻醉下采用小切口非超声乳化手法碎核白内障摘除并行人工晶体植入术。结果术后第1天裸眼视力≥1.0者48眼(8.42%),0.3≤视力<1.0者390眼(68.42%),0.05≤视力<0.3者92眼(16.14%),<0.05者40眼(7.01%)。术中术后并发症有术后后囊破裂9例(1.58%),术后角膜水肿33例(5.79%),虹膜炎性反应21例(3.68%),暂时性高眼压6例(1.05%),前房出血3例(0.53%),玻璃体积血2例(0.35%)。经治疗后恢复。结论小切口非超声乳化手法碎核白内障摘除人工晶体植入术,效果与超声乳化相似,手术安全、器械简单,术后视力恢复快,学习曲线短。值得在基层大批量白内障复明手术中推广应用。     

Distortions of the posterior surface in optical coherence tomography images of the isolated crystalline lens: effect of the lens index gradient

We quantify the posterior surface distortions in optical coherence tomography (OCT) images of isolated crystalline lenses. The posterior radius of curvature and asphericity obtained from OCT images acquired with the beam incident first on the anterior, and then the posterior, surface were compared. The results were compared with predictions of a ray-tracing model which includes the index gradient. The results show that the error in the radius of curvature is within the measurement reproducibility and that it can be corrected by assuming a uniform refractive index. However, accurate asphericity values require a correction algorithm that takes into account the gradient.     

带黑色虹膜隔人工晶体植入对眼外伤患者视功能及怕光症状的影响

目的:眼外伤后无晶状体眼伴虹膜大部分缺损或虹膜全无的患者裸眼视力差,并常有明显的怕光症状,探讨带黑色虹膜隔人工晶体植入手术用于治疗这种患者的安全性和有效性。方法:1998-07/2004-08武警总医院眼科收治的14例(14眼)因创伤后无晶状体伴大部分虹膜缺损或虹膜全无行虹膜隔人工晶体植入手术患者。其中仍有少部分虹膜存在的8例,虹膜全无的6例。14例患者均为Ⅱ期人工晶体植入术。对术前与术后的视力及手术并发症进行了分析。结果:术后视力均有不同程度的提高,其中,视力2.5m(0.05)～4.0的1眼,4.3～4.5的5眼,4.6～4.9的8眼。14例术前均有明显怕光症状的患者,术后怕光症状完全消除的12例,2例怕光症状明显减轻。手术并发症包括2眼术中发生睫状体少量出血,1眼术中发生人工晶体襻断裂,5眼术后出现角膜内皮水肿,1眼术后出现前房少量出血,1眼术后玻璃体出血,2眼术后出现继发青光眼,经处理后均得到了控制。结论:带黑色虹膜隔人工晶体植入手术治疗创伤后无晶状体眼伴大部分虹膜缺损或虹膜全无是安全和有效的。     

Gradients of refractive index in the crystalline lens and transient changes in refraction among patients with diabetes

Transient hyperopic refractive shifts occur on a timescale of weeks in some patients after initiation of therapy for hyperglycemia, and are usually followed by recovery to the original refraction. Possible lenticular origin of these changes is considered in terms of a paraxial gradient index model. Assuming that the lens thickness and curvatures remain unchanged, as observed in practice, it appears possible to account for initial hyperopic refractive shifts of up to a few diopters by reduction in refractive index near the lens center and alteration in the rate of change between center and surface, so that most of the index change occurs closer to the lens surface. Restoration of the original refraction depends on further change in the refractive index distribution with more gradual changes in refractive index from the lens center to its surface. Modeling limitations are discussed.OCIS codes: (330.4460) Ophthalmic optics and devices, (330.7326) Visual optics, modeling     

Characterizing human decellularized crystalline lens capsules as a scaffold for corneal endothelial tissue engineering

The idea of transplanting a sheet of laboratory‐grown corneal endothelium dates back to 1978; however, the ideal scaffold is still lacking. We hypothesized that human crystalline lens capsules (LCs) could qualify as a scaffold and aimed to characterize the properties of this material for endothelial tissue engineering. LCs were isolated from donor eyes, stored at ?80 °C, and decellularized with water and trypsin‐EDTA. The decellularization was investigated by nuclear staining and counting and the capsule thickness was determined by optical coherence tomography and compared with Descemet's membrane (DM). Transparency was examined by spectrometry, and collagenase degradation was performed to evaluate its resistance to degradation. Cell‐scaffold interaction was assessed by measuring focal adhesions surface area on LC and plastic. Finally, primary corneal endothelial cells were grown on LCs to validate the phenotype. Trypsin‐EDTA decellularized most effectively, removing 99% of cells. The mean LC thickness was 35.76 ± 0.43 μm, whereas DM measured 25.93 ± 0.26 μm (p < .0001). Light transmission was 90% for both LC and DM. On a collagenase challenge, LC and amniotic membrane were digested after 13 hr, whereas DM was digested after 17 hr. The surface area of focal adhesions for cells grown on coated LCs was at least double that compared with other conditions, whereas tight junctions, ion pumps, and hexagonal morphology were well maintained when endothelial cells were cultured on LCs. In conclusion, LCs demonstrate excellent scaffolding properties for tissue engineering and sustain the cell phenotype and can be considered a suitable substrate for ocular tissue engineering or as a template for future scaffolds.