小鼠实验性视网膜脱离后光感受器细胞的凋亡

目的 研究小鼠实验性视网膜脱离后光感受器细胞的凋亡情况。 方法 将成年C57Bl/6J小鼠36只分为2组：实验组小鼠18只左眼视网膜下注射1.4%透明质酸钠造成视网膜脱离，对照组小鼠18只左眼仅作巩膜穿刺。分别于手术后1、3、7和28 d摘除眼球，视网膜切片进行组织化学、免疫荧光染色，共聚焦显微镜检查。抗视锥和抗视杆细胞的抗体分别标记视锥和视杆细胞，dUTP缺口末段标记法(TUNEL)标记凋亡细胞。通过计数存活和凋亡的视锥和视杆细胞来定量光感受器细胞的凋亡和细胞丢失。 结果 凋亡细胞只存在于脱离部分视网膜的外核层，凋亡细胞在视网膜脱离后1 d即可检测得到，3 d时达到高峰，7 d后陡然减少。视网膜脱离后视杆和视锥细胞的死亡呈现同样的时程。 结论 凋亡是视网膜脱离后光感受器细胞死亡的主要病理改变。 (中华眼底病杂志, 2006, 22: 124-127)     

光感受器移植治疗视网膜色素变性的近期随访

本文报告了视网膜光感受器移植治疗重度视网膜色素变性的近期治疗效果。作者选取 8例 (8眼 )视网膜色素变性患者施行同种异体光感受器移植 ,对侧 8眼作为对照。入选标准 :年龄 18～ 65岁、Goldmann视野 (视标V4e)中央半径≤ 2 0°、视力≥ 0 0 5(采用“糖尿病性视网膜病变早期治疗研究”的标准 )、全视野ERG视杆细胞反应呈熄灭型、视锥细胞反应b波振幅 >1μV或黄斑局部ERGb波振幅 >0 1μV ,无其它眼科疾病。移植用的光感受器片层来自成人尸体眼 (选自距离中心凹 4～ 5mm、视杆细胞丰富的区域 )。在死亡后 2 4小时内 ,将神经网膜从供眼…     

自适应光学成像系统（MICRO/ZSC-1）活体测定正常人眼视锥细胞密度

目的 对视网膜自适应光学成像系统所得视锥细胞图像进行处理,获取正常人眼底不同区域视锥细胞密度,探讨自适应光学成像系统用于眼科临床实验研究的可行性.方法 横断面研究.利用自适应光学成像系统采集30例正常受试者不同区域视锥细胞图像,对图像进行处理获得正常人眼视网膜不同区域的视锥细胞密度,并采用回归分析法对不同区域的密度进行曲线估计.结果 随测量点与黄斑中心凹的距离增加,视锥细胞密度呈现出降低的趋势.偏离黄斑中心凹0.5°到3°范围内,随着偏离度的增加,视锥细胞密度从70 000个/mm2下降到16 000个/mm2.结论 自适应光学成像系统能够在活体人眼获取清晰的高分辨率视网膜图像,可能可以在眼科临床实验研究中发挥一定的作用.     

采用自适应光学扫描激光检眼镜系统观察健康成年人黄斑区视锥细胞的分布

目的：采用自适应光学扫描激光检眼镜(AO-SLO)系统观察不同年龄健康成年人黄斑区视锥细胞的分布，分析其与年龄的相关性。

方法：选取2023-06/07于我院进行健康体检者100例200眼，根据年龄进行分组，其中A组年龄18-30岁，B组年龄31-40岁，C组年龄41-50岁，D组年龄51-65岁，每组各25例50眼。纳入研究对象双眼均行AO-SLO检查，测量视锥细胞密度。

结果：各组研究对象双眼中心凹偏心率3°处2.4°×2.4°范围视锥细胞密度均有差异(P<0.001)，且各区域视锥细胞密度均呈现较为规律的分布特点，均以颞侧视锥细胞密度最高，由高至低依次为颞侧>鼻侧>下方>上方。各组研究对象双眼黄斑区平均视锥细胞密度分别为14144.38±1082.40、13241.24±535.32、12930.29±727.73、10907.50±490.86 cell/mm²(P<0.001)，提示随着年龄的增长，视锥细胞密度呈下降趋势。相关性分析结果显示，纳入研究对象黄斑区平均视锥细胞密度与年龄呈负相关(r=-0.578，P<0.001)。

结论：AO-SLO检查是一种可无创定量检测视锥细胞的方法，健康人群黄斑区视锥细胞密度与年龄呈负相关关系，50岁以上健康人群视锥细胞密度明显降低。     

视网膜黄斑中心凹无血管区的解剖研究

目的 应用共焦激光扫描显微镜观察及研究黄斑中心凹毛细血管拱环、中心凹无血管区（foveal avascular area, FAZ）的大小及其与年龄增长的关系。 方法 32只尸体眼黄斑部视网膜分离后，应用IV型胶原抗体对视网膜血管进行免疫染色，采用共焦激光扫描显微镜观察结果，分析FAZ的面积、直径与年龄的关系。 结果 清晰地观察到旁中央凹毛细血管网。FAZ的平均面积（0.24±0.13）mm²，平均直径（0.54±0.15）mm。FAZ的面积、直径与年龄无明显相关关系。 结论 共焦激光扫描显微镜与免疫染色法可清晰显示黄斑中心凹毛细血管拱环。FAZ的大小与年龄无明显关系。黄斑部毛细血管拱环完整性可能不受年龄影响。（中华眼底病杂志，2003，19：73-75）     

屈光参差患者双眼血管密度与视网膜厚度的相关性研究

目的：研究屈光参差患者双眼在屈光度数、眼轴及OCTA黄斑区和视乳头区血流密度、黄斑区神经纤维厚度方面的差异,并研究眼轴与眼底血流密度及视网膜厚度的关系,分析其在屈光参差发生、发展中的临床意义。

方法：回顾性分析我院2018-05/11的符合纳入标准的屈光参差患者27例,所有患者均接受双眼的屈光度数、眼压、眼轴及OCTA黄斑区和视乳头区血流密度、黄斑区视网膜厚度的检查。应用SPSS 23.0软件,采用配对t检验分析对比患者双眼在各指标之间的差异。并分析眼轴和黄斑中心无血管区(FAZ)、脉络膜3.14mm²血流密度、黄斑区血流密度及视网膜厚度、视乳头血流密度的关系。

结果： 患者27例中,高度眼的屈光度数及眼轴均大于低度眼(t=-3.559、3.083,P<0.05)。高度眼和低度眼间在OCTA黄斑1mm及3mm浅层血流密度、深层血流密度、视网膜厚度上均无差异(P>0.05)。选取患者中高度眼较低度眼相比,视盘内血流密度大(t=2.36,P=0.022)和上鼻方(SN)血流密度小(t=-2.154,P=0.036)。屈光状态、黄斑中心凹浅层和深层血流密度、旁中心凹深层血流密度、黄斑中心凹及旁中心凹视网膜厚度与眼轴相关(r=-0.897、0.458、0.446、-0.328、0.301、-0.397,均P<0.05)。

结论：屈光参差患者高度眼较低度眼黄斑区3mm×3mm浅层和深层血流密度及视网膜厚度无差异,视盘内及上鼻方血流密度存在差异,余视乳头分区无差异。眼轴与屈光状态、黄斑中心凹浅层和深层血流密度、旁中心凹深层血流密度、黄斑中心凹及旁中心凹视网膜厚度相关。     

视网膜色素变性患者视锥和视杆细胞多焦视网膜电图检测

目的 观察视网膜色素变性(RP)患者视锥细胞和视杆细胞的多焦视网膜电图(mfERG)特征.评估感光细胞功能.方法 选取正常受试者8例8只眼进行视杆细胞mfERG检查.分析不同刺激光亮度对P1波振幅的影响;对19例RP患者38只眼分别进行视杆和视锥细胞mfERG检查.根据局部波形信噪比判断检出率,对视锥细胞mfERG不同类型间的平均视力、P1波振幅惭度进行比较和统计学分析.同时对比分析RP患者视杆和视锥细胞mfERG在各象限P1波振幅的变化.结果 采用0.04 cd/m~2蓝色低刺激光亮度可以稳定记录正常人视杆细胞mfERG反应.RP患者视锥和视杆细胞mfERG有效波形检出率分别为65.79%和10.51%.视锥mfERG I型P1波振幅密度高于Ⅱ型,差异有统计学意义(t=5.21,P=0.0000),平均视力差异无统汁学意义(t=1.15,P=0.612).I型振幅密度与logMAR视力呈负相关(r=-0.48,P=0.04).分别比较RP患者视锥和视杆mfERG局部波形特征发现,两者在各象限的P_1振幅密度在空间上有一定的对应性.结论 RP患者黄斑区视锥细胞的反应存在多样性,视锥细胞mfERG检出率高于视杆细胞,残存视锥和视杆细胞功能在空间上有一定的对应性.     

雌激素对缺氧视网膜Müller细胞色素上皮衍生因子表达的影响

目的:探讨雌激素对缺氧视网膜Müller细胞色素上皮衍生因子（P EDF）表达的影 响。 方法:采用逆转录聚合酶链反应（RT PCR）和Western blotting印 迹分析方法分别测定不同浓度（10^-7、10^-6、10^-5 mmol/L）雌二醇 （E₂）作用于缺氧Müller细胞后，细 胞内 PEDF mRNA及蛋白表达水平。 结果:缺氧24 h后PEDF mRNA及蛋白表达明 显降低， 10^-7、10^-6、10^-5 mmol/L E₂作用于Müller细胞后可明显缓解 由于缺氧引起的细胞内PEDF mRNA及蛋白表达的降低，并与E₂的浓度有关。 结论:雌激素可以调控PEDF的表达 ，其可能在雌激素对视网膜新生血管形成的调控中起重要作用。     

视锥细胞营养不良和Stargardt''s病多焦视网膜电图潜伏期的差异

目的：观察视锥细胞营养不良和Stargardt’s病多焦视网膜电图潜伏期的差异。方法：用VerisⅣ系统记录分析4例视锥细胞营养不良、4例Stargardt’s病和17例正常对照眼的多焦视网膜电图。将两组患者的结果分别与其年龄匹配的正常对照组的结果进行比较。结果：与正常对照组的结果比较，两组患者的多焦视网膜电图的反应密度在1～6环均有显著性下降。两组患者的反应密度在视野中央呈较明显下降，随离心度增加反应密度逐渐趋近正常对照范围。视锥细胞营养不良组的潜伏期在1～3环和5～6环比正常对照组延长，但只有5～6环的数据与正常对照组差异有显著性。Stargardt’s病组的潜伏期在视野中央比正常对照组延长，但只有3～4环的数据差异有显著性。结论：在较大离心度的视野部位，视锥细胞营养不良组的潜伏期比Stargardt’s病组的潜伏期长，因此多焦视网膜电图的潜伏期有可能作为鉴别这两种黄传性暇底病的指标之一。     

Composition of the Inner Nuclear Layer in Human Retina

PurposeThe purpose of this study was to measure the composition of the inner nuclear layer (INL) in the central and peripheral human retina as foundation data for interpreting INL function and dysfunction.MethodsSix postmortem human donor retinas (male and female, aged 31–56 years) were sectioned along the temporal horizontal meridian. Sections were processed with immunofluorescent markers and imaged using high-resolution, multichannel fluorescence microscopy. The density of horizontal, bipolar, amacrine, and Müller cells was quantified between 1 and 12 mm eccentricity with appropriate adjustments for postreceptoral spatial displacements near the fovea.ResultsCone bipolar cells dominate the INL a with density near 50,000 cells/mm² at 1 mm eccentricity and integrated total ∼10 million cells up to 10 mm eccentricity. Outside central retina the spatial density of all cell populations falls but the neuronal makeup of the INL remains relatively constant: a decrease in the proportion of cone bipolar cells (from 52% at 1 mm to 37% at 10 mm) is balanced by an increasing proportion of rod bipolar cells (from 9% to 15%). The proportion of Müller cells near the fovea (17%) is lower than in the peripheral retina (27%).ConclusionsDespite large changes in the absolute density of INL cell populations across the retina, their proportions remain relatively constant. These data may have relevance for interpreting diagnostic signals such as the electroretinogram and optical coherence tomogram.     

Axial length and cone density as assessed with adaptive optics in myopia

Aim:

To assess the variations in cone mosaic in myopia and its correlation with axial length (AL).

Subjects and Methods:

Twenty-five healthy myopic volunteers underwent assessment of photoreceptors using adaptive optics retinal camera at 2° and 3° from the foveal center in four quadrants superior, inferior, temporal and nasal. Data was analyzed using SPSS version 17 (IBM). Multivariable regression analysis was conducted to study the relation between cone density and AL, quadrant around the fovea and eccentricity from the fovea.

Results:

The mean cone density was significantly lower as the eccentricity increased from 2° from the fovea to 3° (18,560 ± 5455–16,404 ± 4494/mm² respectively). There was also a statistically significant difference between four quadrants around the fovea. The correlation of cone density and spacing with AL showed that there was a significant inverse relation of AL with the cone density.

Conclusion:

In myopic patients with good visual acuity cone density around the fovea depends on the quadrant, distance from the fovea as well as the AL. The strength of the relation of AL with cone density depends on the quadrant and distance.     

The Relationship Between Visual Sensitivity and Eccentricity,Cone Density and Outer Segment Length in the Human Foveola

PurposeThe cellular topography of the human foveola, the central 1° diameter of the fovea, is strikingly non-uniform, with a steep increase of cone photoreceptor density and outer segment (OS) length toward its center. Here, we assessed to what extent the specific cellular organization of the foveola of an individual is reflected in visual sensitivity and if sensitivity peaks at the preferred retinal locus of fixation (PRL).MethodsIncrement sensitivity to small-spot, cone-targeted visual stimuli (1 × 1 arcmin, 543-nm light) was recorded psychophysically in four human participants at 17 locations concentric within a 0.2° diameter on and around the PRL with adaptive optics scanning laser ophthalmoscopy-based microstimulation. Sensitivity test spots were aligned with cell-resolved maps of cone density and cone OS length.ResultsPeak sensitivity was at neither the PRL nor the topographical center of the cone mosaic. Within the central 0.1° diameter, a plateau-like sensitivity profile was observed. Cone density and maximal OS length differed significantly across participants, correlating with their peak sensitivity. Based on these results, biophysical simulation allowed to develop a model of visual sensitivity in the foveola, with distance from the PRL (eccentricity), cone density, and OS length as parameters.ConclusionsSmall-spot sensitivity thresholds in healthy retinas will help to establish the range of normal foveolar function in cell-targeted vision testing. Because of the high reproducibility in replicate testing, threshold variability not explained by our model is assumed to be caused by individual cone and bipolar cell weighting at the specific target locations.     

Variations in the cone packing density with eccentricity in emmetropes

Aim

To describe the parafoveal cone arrangement in emmetropic subjects and its variations with eccentricity, meridians and change in axial length in Indian eyes.

Methods

We imaged 25 subjects using compact adaptive optics (AO) retinal camera prototype, the rtx1. Imaging was done at 1, 2, and 3° eccentricity from the fovea in four meridians: nasal, temporal, superior, and inferior.

Results

A statistically significant drop in the cone packing density was observed from 2 to 3° (2° eccentricity=25 350/mm² (5300/mm², 8400–34 800/mm²) 3° eccentricity=20 750/mm² (6000 mm², 9000–33 670/mm²)) P<0.05. The spacing correspondingly increased with increase in distance from the fovea (2° eccentricity=6.9 μm (0.70 μm, 5.95–11.6 μm)) and 3°eccentricity=7.80 μm (1.00 μm, 6.5–13.5 μm) P<0.05. As the axial length increases, the cone density significantly decreases. Interocular variations were noted.

Conclusion

With the advent of AO, visualization at the cellular level is now possible. Understanding the photoreceptor mosaic in the parafoveal space in terms of its density, spacing, and arrangement is crucial so as to detect early pathology and intervene appropriately. Newer therapeutic modalitites that are targeted at the cellular level like yellow micropulse laser, stem cells, gene therapy and so on may be better monitored in terms of safety and efficacy.     

Retinal ganglion cell density and cortical magnification factor in the primate

The question of whether the large area occupied by the primate fovea in the visual cortex (V1) is the result of a selective amplification of the central visual field, or whether it merely reflects the ganglion cell density of the retina, has been a subject of debate for many years. Measurements of the ganglion cell densities are made difficult by lateral displacements of cells around the fovea and the occurrence of amacrine cells in the ganglion cell layer. We have now identified and counted these amacrine cells by GABA immunocytochemistry and by retrograde degeneration of ganglion cells. By reconstructing the fovea from vertical and horizontal serial sections, we were able to measure the densities of cones, cone pedicles and ganglion cells within the same retina. We found 3-4 ganglion cells for every foveal cone. This ratio decreased to one ganglion cell per cone at an eccentricity of 15-20 deg (3-4 mm) and in peripheral retina there are more cones than ganglion cells. The ganglion cell density changes by a factor of 1000-4000 between peripheral and central retina. A comparable gradient has been reported for the representation of the peripheral and central visual field in V1. We suggest that ganglion cell density can fully account for the cortical magnification factor and there is no need to postulate a selective amplification of the foveal representation.     

The Synaptic Complex of Cones in the Fovea and in the Periphery of the Macaque Monkey Retina

Parallel pathways for visual information processing start at the first synapse of the retina, at the cone pedicle. At least eight different types of bipolar cells receive direct synaptic input from an individual cone. The present study explores whether enough synaptic sites are available at the cone pedicle to supply all these bipolar cells. Monkey retinae were optimally fixed for electron microscopy. Serial horizontal sections were cut through the cone pedicle layer in a piece close to the fovea (eccentricity: 0.75 mm) and in a peripheral piece (eccentricity: 5–6 mm). The ribbon synapses (triads) at the cone pedicle base were analysed. The average number of synaptic ribbons per cone pedicle increased from 21.4 ± 1.6 (n = 26) in central retina to 41.8 ± 3 (n = 14) in peripheral retina. Five central and five peripheral pedicles were reconstructed and the invaginating bipolar cell dendrites forming the central elements of the triads were characterized. Close to the fovea an average of 18 invaginating bipolar cell dendrites was found, in peripheral retina the average was 90. Pedicles of foveal cones have one invaginating central process per ribbon, pedicles of peripheral cones have two. It is possible that midget bipolar cell dendrites occupy the majority of triads in the fovea, while in peripheral retina both midget and diffuse bipolar cell dendrites share the triads. Copyright © 1996 Elsevier Science Ltd.     

Blur discrimination of the human eye in the near retinal periphery.

BACKGROUND: Although blur discrimination in the foveal region has been investigated, knowledge regarding the effect of retinal eccentricity is limited. METHODS: The initial blur discrimination threshold and the blur detection threshold were assessed psychophysically and compared at the fovea and in the near retinal periphery (up to 8 degrees) with accommodation paralyzed. RESULTS: The blur discrimination and blur detection thresholds increased progressively with retinal eccentricity, with the latter being about twice as large and increasing twice as fast as the former. However, the group mean blur ratio between these two parameters remained relatively constant (0.56) with retinal eccentricity. CONCLUSIONS: The more sensitive blur discrimination vs. blur detection findings may be attributed to variation in the optical modulation transfer function with retinal defocus and to a perceptually based blur-buffering mechanism. The reduced blur sensitivity found with increased retinal eccentricity might be attributed to cone photoreceptor/ganglion cell sampling limitations, sharpness overconstancy, reduced visual attention, and slightly degraded visual optics.     

Count and density of human retinal photoreceptors

This investigation was directed at determining the count and regional distribution of photoreceptors in the eyes of 21 human cornea donors aged between 2 and 90 years. Mean count of rods was 60 123 000 ±12907000, and mean cone count was 3173000 ± 555000. Determined 40 m away from the foveola, cone density measured 125 500 cones/mm². Extrapolating the distribution curve, cone concentration in the foveal center can be assumed to be about 150 000 cells/mm² to 180 000 cones/mm². Towards the retinal periphery, cone density decreased from 6000 cones/mm² at a distance of 1.5 mm from the fovea to 2500 cells/mm² close to the ora serrata. Comparing different fundus regions, cone concentration was significantly highest in the nasal region. Cone diameter increased from the center towards the periphery. At a distance of 40 m away from the foveola, it measured about 3.3 m, and in the outer retinal regions about 10 m Rod density was highest in a ring-like area at a distance of about 3–5 mm from the foveola with a mean of 72 246 ± 17 295 cells/mm². Rod density peaked at 150 000 rods/mm². It decreased towards the retinal periphery to 30 000–40 000 rods/mm². Rod diameter increased from 3 m at the area with the highest rod density to 5.5 m in the periphery. The hexagonal rod and cone inner segments were regularly arranged in a honey-comb fashion.Supported by the Deutsche Forschungsgemeinschaft (Klinische Forschergruppe Glaukome Na 55/6-1/Jo) Correspondence to: J.B. Jonas     

Spatial resolution across the macaque retina

Grating acuity was measured as a function of eccentricity from the fovea in two macaques. A vertical-horizontal orientation discrimination was used to determine acuity, and the retinal locus of the test grating was controlled by training them to fixate a spot placed at various distances from the stimulus. Their head was fixed in place and fixation was monitored with a scleral search coil. The acuity of monkeys across the retina was similar to that previously measured in human subjects, reaching a peak of about 38 c/deg at the fovea, and decreasing about 10-fold by 30 deg eccentricity. Acuity was slightly higher in the temporal than in the nasal visual field. The shape of the acuity-eccentricity function suggested a dependence on cone density near the fovea, and on the density of P ganglion cells at eccentricities beyond 10 deg. Existing physiological data suggest the possibility that macaque acuity may also be limited in part by spatial averaging across the receptive field of retinal ganglion cells.