Department of Medical Physics, Tarbiat Modares University, Tehran, Iran.
Ultrasonics. 2012 Feb;52(2):208-14. doi: 10.1016/j.ultras.2011.08.004. Epub 2011 Aug 27.
Elastic modulus estimation may be an important clinical criterion, as it seems to affect such eye parameters as intraocular pressure, ocular pulsation, blood flow, effect of topical medications, and post-refractive surgery complications. The purpose of this study was to examine the differences in elasticity in the ocular axial length, posterior wall thickness (posterior pole), and retina-choroid thickness under normal and aged-related macular degeneration (AMD) conditions in the human eye by directly estimating the elastic modulus with sequential and noninvasive ultrasound image processing.
In this study, 25 healthy subjects and 20 patients with non-neovascular AMD participated in the experiment. The deformation of the ocular axial length, posterior wall thickness and retina-choroid complex thickness was captured using high-resolution ultrasonography before and after loading. The B-mode (20MHz) and A-mode (8MHz) frames were obtained and processed with an echo tracking technique. The elastic modulus was estimated using changes in ocular axial length, posterior wall thickness and retina-choroid complex thickness and with applied stress measurements.
There was a significant difference (p<0.05) in the ocular axial length elastic modulus between the AMD and healthy subjects (AMD patients: 95.165±26.431kPa, vs. healthy subjects: 49.539±25.867kPa). Moreover, there was a statistically significant difference (p<0.05) in the posterior wall thickness elastic modulus between AMD patients and healthy subjects (AMD patients: 50.519±12.295kPa, vs. healthy subjects: 20.519±11.827kPa). However, no statistically significant difference (p-value>0.05) was found in the retina-choroid complex elastic modulus between the two groups (AMD patients: 20.134±3.898kPa, vs. healthy subjects: 15.630±4.250kPa).
Although the results were obtained examining a relatively low number of patients, it would appear that noninvasive ultrasound estimation of the local elastic moduli of ocular axial length and posterior wall thickness is suited to aid in detection of the non-exudative AMD thus manifesting its potential as a screening tool in symptom-free individuals.
弹性模量的估计可能是一个重要的临床标准，因为它似乎会影响眼压、眼搏动、血流、局部药物的效果和屈光手术后并发症等眼部参数。本研究旨在通过顺序和非侵入性超声图像处理直接估计弹性模量，来检测正常和年龄相关性黄斑变性（AMD）条件下人眼眼球轴向长度、后极壁厚度（后极）和视网膜脉络膜厚度的弹性差异。
本研究中，25 名健康受试者和 20 名非新生血管性 AMD 患者参与了实验。使用高分辨率超声在加载前后捕获眼球轴向长度、后极壁厚度和视网膜脉络膜复合体厚度的变形。获得 B 模式（20MHz）和 A 模式（8MHz）帧，并使用回声跟踪技术进行处理。使用眼球轴向长度、后极壁厚度和视网膜脉络膜复合体厚度的变化以及施加的应力测量来估计弹性模量。
AMD 组和健康组的眼球轴向长度弹性模量有显著差异（p<0.05）（AMD 患者：95.165±26.431kPa，健康组：49.539±25.867kPa）。此外，AMD 患者和健康组的后极壁厚度弹性模量也有显著差异（p<0.05）（AMD 患者：50.519±12.295kPa，健康组：20.519±11.827kPa）。然而，两组间视网膜脉络膜复合体弹性模量无统计学差异（p 值>0.05）（AMD 患者：20.134±3.898kPa，健康组：15.630±4.250kPa）。
尽管研究结果是通过对相对较少的患者进行检查获得的，但似乎非侵入性超声对眼球轴向长度和后极壁厚度的局部弹性模量的估计适合于辅助检测非渗出性 AMD，从而显示其在无症状个体中的筛查工具的潜力。
