OCT及OCTA在阿尔茨海默病诊断中的研究进展

阿尔茨海默病是一种进行性且不可逆转的神经系统疾病,由于视网膜和中枢神经系统有相似的胚胎起源和生理特征,眼科检查可提供简单无创的诊断方法。光学相干断层扫描技术(OCT)能够精确地测量视网膜各个组织层面的厚度,以评估视网膜的退行性改变,光学相干断层扫描血管成像(OCTA)可以提供高分辨率三维成像,从而更直观地检测视网膜血管的变化,间接地反映脑神经元和血管的病理特征。就OCT测量视网膜厚度及OCTA测量视网膜血流变化在阿尔茨海默病诊断中的研究进展进行综述。     

Robust rigid registration of retinal angiograms through optimization

Retinal fundus photographs are employed as standard diagnostic tools in ophthalmology. Serial photographs of the flow of fluorescein and indocyanine green (ICG) dye are used to determine the areas of the retinal lesions. For objective measurements of features, the registration of the images is a necessity. In this paper, we employ optimization techniques for registration with the help of 2-parameter translational motion model of retinal angiograms, based on non-linear pre-processing (Wiener filtering and morphological gradient) and computation of the similarity criteria for the alignment of the two gradient images for any given rigid transformation. The optimization methods are effectively employed to minimize the similarity criterion.

The presence of noise, the variations in the background and the temporal variation of the fluorescence level pose serious problems in obtaining a robust registration of the retinal images. Moreover, local search strategies are not robust in the case of ICG angiograms, even if one uses a multiresolution approach.

The present work makes a systematic comparison of different optimization techniques, namely the minimization method derived from the optical flow formulation, the Nelder-Mead local search and the HCIAC ant colony metaheuristic, each optimizing a similarity criterion for the gradient images. The impact of the resolution and median filtering of gradient image is studied and the robustness of the approaches is tested through experimental studies, performed on macular fluorescein and ICG angiographies.

Our proposed optimization techniques have shown interesting results especially for high resolution difficult registration problems. Moreover, this approach seems promising for affine (6-parameter motion model) or elastical registrations.     

Vehicle of triamcinolone acetonide is associated with retinal toxicity and transient increase of lens density

Background Intravitreal triamcinolone acetonide (TA) has been widely used as a therapeutic method for many ocular diseases, but a consensus on an appropriate safe therapeutic window of dosage for intravitreal injection, and whether vehicle of TA should be reduced or eliminated, has not yet been reached. The aim of this article is to investigate these issues.Methods Forty New Zealand white rabbits were divided into four experimental groups and one control group. Four or 25 mg TA, with vehicle either reduced or not, was injected into the vitreous cavity of rabbits in experimental groups. Rabbits in the control group received 0.2 ml intravitreal sterile saline solution. Intraocular pressures (IOP) were measured by a Tonopen tonometer. Values of lens density were measured by a Pentacam system. Soluble protein, total antioxidation capacity, reduced glutathione (GSH), glutathion peroxidase (GSH-px), and superoxide dismutase (SOD) in lens were measured by specific kits. ERG and pathological examinations, including light and electron microscopy of the retina, were also performed.Results Elevation of IOP was noted in all experimental groups after intravitreal TA (P<0.01, paired t-test). Significant increase of lens density was noticed at 1 week after intravitreal TA in the 25 mg vehicle-containing group (P<0.0001, paired t-test). Significant loss of GSH-px activity was noticed at the end of the study (P<0.05, paired t-test), while SOD activity increased (P<0.05, paired t-test). Amplitudes of ERG waves declined significantly in vehicle-containing groups (P<0.01, paired t-test) at the end of the study. Pathological examination showed obvious retinal toxicity in vehicle-containing groups.Conclusions Vehicle of TA should be eliminated or reduced before intravitreal injection to avoid potential retinal toxicity and transient increase in lens density.Presented at Chinese Academy of Fundus Disease Meeting, April, 2005.This study was supported by the 985 Fund of Peking University, Beijing.The authors have no financial interest in any instruments or drugs mentioned in this study.     

Diagnostic accuracy of the Retinal Thickness Analyser: differentiation between normal eyes and eyes with glaucoma or macular pathologies

Background The Retinal Thickness Analyser (RTA) is intended to detect glaucomatous changes as well as macular pathologies at the posterior pole. We determined the diagnostic accuracy for eyes with manifest glaucoma or macular diseases.Methods We examined 71 eyes with long-term, established eye conditions. Included were 28 eyes with glaucoma, 21 with different macular diseases and 22 normal eyes. All examinations were evaluated in a blind-test by RTA experts without any clinical information on the patients. After comparison of the RTA interpretation with the clinical diagnosis, we determined sensitivity, specificity, positive and negative predictive values.Results Of 71 examinations, 15 (21%) were not interpretable. If these results are excluded, the following diagnostic accuracy values were calculated for glaucoma and macular disorders respectively: sensitivity 75 and 59%, specificity 55 and 97%, positive predictive value 48 and 90% and negative predictive value 80 and 84%. These values were not significantly different when both eyes of each patient were included in the final analysis (n=133).Conclusion The diagnostic values of the RTA determined in this case control study were not satisfactory. However, no clinical information was used in the assessment. The extent to which additional clinical information increases the diagnostic value remains to be determined.     

Ocular changes in the mouse embryo following acute maternal ethanol intoxication

The development of the eye was investigated in the mouse embryo following a single administration of ethanol plus [3H]thymidine to the dam on day 13 of gestation. After 1 hr there was no difference in the number of labelled cells/100 micron 2 in the neural layer of the retina compared to controls, but there was an alcohol-related reduction in labelling density. After 24 hr there was an increase in the numbers of both pyknotic cells and mitotic figures, breaks occurred in the inner surface of the retina and cell debris was being extruded into the posterior chamber. At 48 hr the increase in pyknotic cells persisted, but there was less evidence of cell debris and the borders had been repaired. The estimated cell cycle time in the neural progenitor cells following maternal alcohol administration was increased 7-fold compared to controls. Morphometric analysis revealed that after 48 hr there were significant alcohol-related reductions in the width and depth of the eye, in the thickness of the neural layer and in the interocular distance. It appears that many of the ophthalmic abnormalities reported in human fetal alcohol syndrome can be produced in the mouse embryo following a single episode of acute maternal intoxication during a critical period of ocular ontogeny, and that they evolve primarily from disturbances in the normal patterns of recruitment and loss of neural progenitor cells in the developing retina.     

妊高征与眼底视网膜病变的临床探讨

目的 :探讨妊高征患者临床特征与视网膜病变的关系。方法 :观察 2 2 0例妊高征患者的眼底情况。结果 :视网膜病变与水肿关系不密切 ,与平均动脉压、蛋白尿的严重程度、病程及红细胞压积有密切关系 ;有眼底改变者 118例 ,占 5 0 .3%。结论 :眼底镜检查是临床上借以了解视网膜血管的常用方法 ,并可反映妊高征病情的程度 ,为产程处理提供依据     

老年人视网膜中央血管在前部视神经的解剖特征

目的：观察老年人前部视神经视网膜中央血管的解剖特征。 方法：通过组织连续切片和计算机影像分析，观察60~82岁老年人的18只眼球标本中无解剖变异的视网膜中央动脉(CRA)15条，视网膜中央静脉（CRV）23条在筛板前、筛板区及筛板后的管径变化。 结果：老年人筛板前、筛板区、筛板后CRA平均面积的均值分别为（12.70,17.40,18.00）×10^-3mm^2_;平均周长的均值分别为0.56，0.56，0.57mm，平均周长之间相比无显著差异。CRV平均面积的均值分别为（7.00，5.40，7.90）×10^-3mm²；平均周长的均值分别为0.44，0.38，0.41mm；CRV平均周长筛板前与筛板区相比，筛板区与筛板后相比均有显著差异。 结论：老年人CRA眼球内外管径一致；CRV在筛板区管径最小。 （中华眼底病杂志，1997，13：213-214）