QUANTITATIVE ANALYSIS OF AGING RETINA

在眼底大体正常的供眼中，视杆细胞的数目 光感受器从中年开始稳步下降，特别是在中年 球果数量稳定，但球果数量稳定。我们打算测试一下 使用两个人眼来源的3个相关假设：1)眼库捐赠者 在死亡后2小时内获得的眼睛，以及2)在手术中从 接受过术前眼科检查、视力检查的癌症患者 功能和眼底照相。来自两个来源的保存的眼睛将 根据黄斑改变进行分级。假设1：与年龄相关的细胞丢失 中央视网膜包括少数对蓝色敏感的视锥细胞， 基于临床和心理物理证据的思考 更容易老化的。使用免疫细胞化学和 人类蓝视蛋白的抗体，我们将确定是否有数量 与70岁以上捐赠者相比，70岁以上捐赠者视网膜中标记的视锥细胞减少 我们之前研究的供者年龄在40-59岁之间。假设2：外部 在与年龄相关的杆件丢失中存活的杆件节段扩大以维持 恒定的总视紫红质。暗视敏感度降低是由于术后 接受因素。因为眼底反射仪证据表明 视网膜中央视紫红质含量随增龄而稳定，但有所下降 杆数，我们将用分光光度法和 定量光学显微镜检测杆状密度和外节体积 在年轻(&50岁)和老年捐赠者的同眼中央视网膜。 视网膜内两条主要通路之一的下一个神经元 视杆信息传递给神经节细胞中的视杆双极细胞。vbl.使用 免疫细胞化学和蛋白激酶C抗体，我们将 青壮年和老年供者视杆双极细胞数量的测定 眼睛，并使用电子显微镜，我们将确定发散和 杆和杆双极之间的会聚。假设3： 黄斑旁黄斑对与年龄相关的光感受器丢失的脆弱性，如 以及色素上皮(PE)的地理萎缩，以及 中心凹视锥的保留与黄斑中心的区域差异有关。 下层PE和Bruchs膜(BM)。为了确定PE是否 细胞损失伴随着杆状损失，我们将量化PE的地形 不同年龄组视网膜细胞的空间密度和体积 使用定量光学显微镜的光感受器拓扑图。虽然 视杆丢失发生在视网膜中，没有典型的肉眼可见的变化 黄斑变性，大多数成人视网膜含有玻璃体和基底部 层流沉积(BLD)，棒材损失的最简单解释是 存在PE和BM的亚临床病理。因此，我们将 比较相对安全的黄斑中心凹和脆弱的副中央凹 电子显微镜下可见BLD的存在。通过使用其中的样本 视网膜仍然附着在PE上，并通过切开组织块 无论是垂直平面还是切向平面，PE和BM都将是精细结构 与潜在的光感受器细胞数有关。

In donor eyes with macroscopically normal fundi, the number of rod photoreceptors decline steadily from mid-life, particularly in the parafoveal, whereas the number of cones is stable. We propose to test 3 related hypotheses using two sources of human eyes: 1) Eye Bank donors eyes obtained within 2 hr of death, and 2) eyes obtained at surgery from cancer patients who have had pre-operative eye exams, testing of visual function, and fundus photography. Preserved eyes from both sources will be graded for macular changes. Hypothesis 1: Age-related cell loss in central retina includes the small population of blue-sensitive cones, thought on the basis of clinical and psychophysical evidence to be preferentially vulnerable to aging. Using immunocytochemistry and an antibody to the human blue opsin, we will determine if the number of labeled cones is reduced in retinas from donors over age 70 compared to donors aged 40-59 yr that we studied previously. Hypothesis 2: Outer segments of rods surviving age-related rod loss expand to maintain constant total rhodopsin. Decreased scotopic sensitivity is due to post- receptoral factors. Because fundus reflectrometry evidence suggests that rhodopsin content in central retina is stable with age despite decreasing rod number, we will measure rhodopsin content using spectrophotometry and rod density and outer segment volume using quantitative light microscopy in the central retina of fellow eyes in young (<50 yr) and old donors. The next neuron in one of the 2 major intra-retinal pathways transmitting rod information to ganglion cells in the rod bipolar cell. Using immunocytochemistry and an antibody to protein kinase C, we will determine the number of rod bipolar cells in young adult and aged donor eyes, and using electron microscopy, we will determine diverge and convergence between rods and rod bipolars. Hypothesis 3: The vulnerability of the parafoveal for age-related photoreceptor loss, as well as for geographic atrophy of the pigment epithelium (PE), and the sparing of foveal cones is related to regional differences in the underlying PE and Bruch's membrane (BM). In order to determine if PE cell loss accompanies rod loss, we will quantify the topography of PE cell spatial density and volume in retinas of different ages with known photoreceptor topography using quantitative light microscopy. Although rod loss occurs in retina without the grossly visible changes typical of macular degeneration, most of adult retinas contain drusen and basal laminar deposit (BLD), and the simplest explanation for rod loss is the presence of subclinical pathology of PE and BM. Therefore, we will compare the relatively spared fovea and the vulnerable parafoveal for the presence of BLD seen by electron microscopy. By using specimens in which the retina remains attached to the PE and by cutting tissue blocks in both vertical and tangential planes, PE and BM fine structure will be related to underlying photoreceptor cell number.