Investigations of Human Cone Directionality

人体锥体方向性的研究

• 批准号: 7679431
• 负责人: Stephen A Burns
• 金额: $ 36.78万
• 依托单位: TRUSTEES OF INDIANA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-11-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7679431
• 关键词: Activities of Daily Living; Age; Age related macular degeneration; Age-Years; Aging; Area; Arts; Behavior; Blindness; Burn injury; Caliber; Cells; Collection; Color; Contrast Sensitivity; Coupled; Data; Densitometry; Deposition; Development; Drusen; Epiretinal Membrane; Equilibrium; Eye; Figs - dietary; Fluorescence; Frequencies; Grant; Health; Human; Image; Individual; Investigation; Laboratories; Length; Light; Link; Lipofuscin; Location; Maps; Measurement; Measures; Modeling; Optics; Pathway interactions; Patients; Personal Communication; Photoreceptors; Population; Prevalence; Property; Psychophysiology; Pupil; Radial; Relative (related person); Resolution; Retina; Retinal; Retinal Cone; Risk; Sampling; Side; Staging; Structure; System; Techniques; Technology; Testing; Time; Tissues; Variant; Vision; Visual; Visual Acuity; absorption; adaptive optics; base; density; fovea centralis; improved; in vivo; instrumentation; light scattering; optical imaging; quantum

DESCRIPTION (provided by applicant): The human fovea is highly specialized for excellent visual acuity and contrast sensitivity. To provide this capability the cones in the center of the fovea are smaller in diameter than parafoveal cones. To compensate for the decreases in cross sectional area relative to cones further from the center, the foveal cones have longer outer segments, and therefore a higher optical density of their cone photopigments. The cones also act as antennae: the inner segments collect light preferentially from the pupil and guide the light along the outer segments. These waveguide properties of the cones also vary across the fovea, with the cones in the foveal center accepting light from a wider region of the pupil than cones just a few hundred microns away. This increased collection of light from the pupil both increases their sensitivity and also allows them to use a wider region of the pupil, and thereby have higher optical resolution. Thus, the fovea represents a balance of factors which are tightly coupled to provide excellent vision. As the eye ages this balance may change. The curvature of the fovea changes (the foveal pit widens) and irregularities in the symmetric distribution of the cone photopigment appear. In addition, the high optical density of the foveal cones decreases, becoming more similar to cones a few degrees away from the center of the fovea. This change in optical density may occur due to either a decrease in the outer segment length, decreases in the amount of photopigment, or changes in the waveguide properties of the cones. With early ARM the optical density of both the foveal and parafoveal cones decrease even more. Modern optical technology now allows us to directly measure the optical factors controlling the capture of light by the foveal cones. We will use state of the art instrumentation and analysis techniques to study the fovea in normals and patients with early age-related macular degeneration (ARM). We will use adaptive optics imaging with an SLO to directly image the cones and related structures. We will use photoreceptor alignment reflectometry and retinal densitometry to measure the optical properties of the cones. We will relate changes to the cones in aging and early ARM to RPE health, determined by measuring near infrared light scattering and lipofuscin fluorescence. We will test whether changes in RPE health are related to changes in the optical efficiency of the overlying cones. These studies will provide a unique quantitative framework for evaluating the fovea of the human eye as an imaging system, and provide information on how the functional capacities of the fovea change with both age and early ARM. Such measurements will be critical for both understanding the development of ARM, and to better explain visual complications that occur prior to the permanent loss of vision.

描述（由申请人提供）：人类中央凹高度特化，具有出色的视力和对比敏感度。为了提供这种能力，位于中央凹中心的视锥细胞的直径小于中央凹旁视锥细胞的直径。为了补偿相对于远离中心的视锥细胞横截面积的减小，中心凹视锥细胞具有更长的外段，因此其视锥细胞感光色素的光密度更高。视锥细胞还充当天线：内部节段优先收集来自瞳孔的光，并沿着外部节段引导光。视锥细胞的这些波导特性在整个中央凹中也有所不同，中央凹中心的视锥细胞比仅几百微米外的视锥细胞接受来自更广泛的瞳孔区域的光。来自瞳孔的光收集的增加既提高了它们的灵敏度，也使它们能够使用更广泛的瞳孔区域，从而具有更高的光学分辨率。因此，中央凹代表了紧密耦合以提供良好视力的因素的平衡。随着眼睛老化，这种平衡可能会改变。中央凹的曲率发生变化（中央凹坑变宽），并且圆锥感光色素的对称分布出现不规则。此外，中央凹锥体的高光密度降低，变得更类似于远离中央凹中心几度的锥体。光密度的这种变化可能是由于外部段长度的减少、感光色素量的减少或锥体的波导特性的变化而发生的。在早期 ARM 中，中心凹和中心凹旁视锥细胞的光密度下降得更多。 现代光学技术现在使我们能够直接测量控制中央凹锥体捕获光的光学因素。我们将使用最先进的仪器和分析技术来研究正常人和早期年龄相关性黄斑变性 (ARM) 患者的中央凹。我们将使用带有 SLO 的自适应光学成像来直接对视锥细胞和相关结构进行成像。我们将使用光感受器对准反射计和视网膜密度计来测量视锥细胞的光学特性。我们将通过测量近红外光散射和脂褐质荧光来确定衰老和早期 ARM 中视锥细胞的变化与 RPE 健康状况之间的关系。我们将测试 RPE 健康状况的变化是否与上方视锥细胞光学效率的变化有关。 这些研究将为评估人眼中央凹作为成像系统提供独特的定量框架，并提供有关中央凹功能如何随年龄和早期 ARM 变化的信息。此类测量对于了解 ARM 的发展以及更好地解释永久性视力丧失之前发生的视觉并发症至关重要。