AIM—To analyse the human corneal stroma in extreme hydration to discover if its structure is responsible for corneal stability. METHODS—Corneas in several hydration states were used: postmortem control corneas (PM; n=3), corneas left for 1 day in phosphate buffered saline (PBS; n=4), and corneas left for 1 day (n=4), 2 days (n=4), 3 days (n=2), and 4 days (n=4) in deionised water. All corneas were fixed under standardised conditions and processed for light and electron microscopy. In addition, two fresh corneas from the operating theatre were studied which were processed 6 months after storage in sodium cacodylate buffer. RESULTS—After 1 day in deionised water maximal stromal swelling was reached which did not change up to 4 days. The stroma of deionised water corneas (1400 µm) was much thicker than that of PBS corneas (650 µm) and PM corneas (450 µm). Deionised water treatment led to disappearance of all keratocytes leaving only remnants of nuclei and large interlamellar spaces. In these specimens the distance between the collagen fibres had increased significantly, but the diameter of the collagen fibres did not seem to be affected. A remarkable observation was that the most anterior part of the stroma (100-120 µm) in all deionised water specimens and those stored for 6 months in buffer was not swollen, indicating that the tightly interwoven anterior lamellae are resistant to extreme non-physiological hydration states. CONCLUSIONS—The rigidity of the most anterior part of the corneal stroma in extreme hydration states points to an important role in maintenance of corneal curvature. Since a large part of this rigid anterior part of the stroma is either removed (PRK) or intersected (LASIK), it is possible that in the long run patients who underwent refractive surgery may be confronted with optical problems.
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机译:目的:分析极端水合作用中的人角膜基质,以了解其结构是否对角膜稳定性负责。 方法:使用了几种水合状态的角膜:验尸后角膜(PM; n = 3),角膜留给在磷酸盐缓冲液(PBS; n = 4)中放置1天,并保留角膜1天(n = 4),2天(n = 4),3天(n = 2)和4天(n = 4)在去离子水中。将所有角膜固定在标准条件下,并进行光学和电子显微镜检查。此外,还研究了两个来自手术室的新鲜角膜,将它们保存在椰油酸钠缓冲液中6个月后进行处理。 结果-在去离子水中放置1天后,达到最大基质溶胀,在4天内没有变化。去离子水角膜(1400 µm)的基质比PBS角膜(650 µm)和PM角膜(450 µm)的基质厚得多。去离子水处理导致所有角膜细胞消失,仅留下细胞核残留和较大的层间空间。在这些样品中,胶原纤维之间的距离显着增加,但是胶原纤维的直径似乎没有受到影响。值得注意的是,在所有去离子水标本中以及在缓冲液中存放了6个月的标本,基质的最前部分(100-120μm)都没有肿胀,这表明紧密交织的前片对极端的非生理性水合作用具有抵抗力结论。在极端水合作用状态下,角膜基质最前部的刚度指出了维持角膜曲率的重要作用。由于基质的这个刚性前部的大部分已被切除(PRK)或相交(LASIK),因此从长远来看,接受屈光手术的患者可能会遇到光学问题。