Eye Laser Institute, Halle, Germany.
Graefes Arch Clin Exp Ophthalmol. 2011 Mar;249(3):399-406. doi: 10.1007/s00417-010-1504-9. Epub 2010 Sep 18.
Recently, glyceraldehyde-induced crosslinking was proposed by us for the treatment of progressive myopia, increasing significantly the biomechanical rigidity of sclera. The aim of the present study was to investigate the changes in thermo-mechanical stability after scleral glyceraldehyde crosslinking, allowing a better evaluation of the efficacy of crosslinking.
One hundred and twenty six porcine eyes were retrieved from the local abattoir. Using hot saline solution, the threshold shrinkage temperature (Ts) was determined for both equatorial scleral strips and whole eye globes incubated with glyceraldehyde for 4 days. Untreated control samples and specimens crosslinked with formaldehyde for 4 days were tested for comparison. In the globes, a small 6 mm limbus-parallel scleral strip was excised 5 mm behind the limbus to allow extrusion of the vitreous, facilitating heat-induced globe contraction. After heat exposure, the eyes were examined histologically by light microscopy.
There was significant Maillard browning of the sclera after incubation with glyceraldehyde. The contraction temperature determined in the glyceraldehyde group was 78°C for both scleral strips and globes, in the formaldehyde group 88°C for scleral strips and 92°C for globes, and in non-crosslinked controls 62°C for scleral strips and 68°C for globes. Interestingly, the eye balls contracted in an implosion-like manner, leading to an abrupt reduction in eye volume by about one third. On light microscopy, scleral thickening, heat denaturation of collagen fibers, and loss of birefringence were noted.
Scleral collagen crosslinking by glyceraldehyde proved very efficient in increasing the scleral thermomechanical stability by at least 10°C in Ts, stabilizing the eye shape and preventing the shrinkage of the eye in all dimensions. There is hope that, in a similar manner, glyceraldehyde crosslinking can stabilize the scleral collagen crosslinks and eye shape in myopia, stopping progression of scleral thinning and stretching.
最近，我们提出了甘油醛交联法来治疗进行性近视，显著增加巩膜的生物力学刚性。本研究的目的是研究巩膜甘油醛交联后热机械稳定性的变化，以便更好地评估交联的效果。
从当地屠宰场收集了 126 只猪眼。使用热盐水溶液，确定了在甘油醛孵育 4 天后赤道部巩膜条带和整个眼球的阈值收缩温度（Ts）。测试了未经处理的对照样本和用甲醛交联 4 天的样本作为对照。在眼球中，在距角膜缘 5mm 处切除一个 6mm 长的角膜缘平行巩膜条带，以排出玻璃体，便于热诱导的眼球收缩。热暴露后，通过光镜检查眼睛的组织学变化。
巩膜用甘油醛孵育后出现明显的美拉德褐变。甘油醛组巩膜条带和眼球的收缩温度分别为 78°C 和 88°C（巩膜条带）和 92°C（眼球），甲醛组为 88°C 和 88°C（巩膜条带）和 92°C（眼球），未交联对照组为 62°C 和 68°C（巩膜条带）和 68°C（眼球）。有趣的是，眼球呈内爆样收缩，导致眼球体积突然减少约三分之一。光镜下可见巩膜增厚、胶原纤维热变性和双折射丧失。
甘油醛交联巩膜胶原非常有效地增加了巩膜的热机械稳定性，至少使 Ts 增加了 10°C，稳定了眼球形状，防止了眼球在所有方向上的收缩。希望甘油醛交联能够以类似的方式稳定近视患者巩膜胶原交联和眼球形状，阻止巩膜变薄和拉伸的进展。
