Queensland Eye Institute, South Brisbane, Queensland, Australia.
Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia.
Ophthalmic Plast Reconstr Surg. 2019 Nov/Dec;35(6):600-603. doi: 10.1097/IOP.0000000000001413.
A follow-up experimental study on the exposure of animal tarsal plate to ultraviolet-A radiation aimed at establishing an optimum range for safe irradiation conditions.
Sheep tarsus specimens were excised postmortem and then subjected to irradiation with ultraviolet-A rays (wavelength 365 nm) at higher irradiances than those reported in an initial study, using a laboratory radiation source. The mechanical properties (tensile strength and Young's modulus) of irradiated and nonirradiated samples were evaluated in a mechanical tester. The test and control specimens were examined histologically with an aim to assess the effects of radiation upon the meibomian glands and tarsal collagen networks, and to establish a safe range for the exposure irradiance level.
As expected, irradiation induced both stiffening and strengthening of the tarsal plate specimens. At an irradiance of 50 mW/cm for 3-minute exposure, these effects were at their maximum level, after which a decline in mechanical characteristics were observed. No destruction of the tarsal connective tissue or the meibomian glands were noticed up to an irradiance of 125 mW/cm for 3-minute exposure, corresponding to a fluence of 22.5 J/cm. Histology revealed that the collagen network surrounding the glands were packed more compactly following irradiation. At a fluence of 45 J/cm, massive destruction of periglandular collagen-rich network and meibocytes were demonstrated histologically.
The study indicates that irradiation of tarsal collagen leading to tissue stiffening shall be carried out at levels of fluence between 10 and 15 J/cm, a region that is deemed safe. The exposure time can be adjusted according to the surgeon's decision.Safe irradiation conditions are established for the exposure of ex vivo ovine tarsus to ultraviolet-A radiation as a potentially effective treatment for eyelid laxity in human patients.
一项针对动物跗骨板暴露于中波紫外线（UVA）辐射的后续实验研究，旨在确定安全照射条件的最佳范围。
从死后的羊跗骨标本中取出标本，然后使用实验室辐射源对其进行高于初始研究中报告的中波紫外线（波长 365nm）的照射。在机械试验机上评估辐照和未辐照样品的机械性能（拉伸强度和杨氏模量）。用旨在评估辐射对睑板腺和跗骨胶原网络影响的方法对测试和对照标本进行组织学检查，以确定暴露辐照度水平的安全范围。
正如预期的那样，照射导致跗骨板标本的硬度和强度增加。在 50mW/cm 的辐照度下暴露 3 分钟，这些效果达到最大水平，之后机械特性下降。在 125mW/cm 的辐照度下暴露 3 分钟，即 22.5J/cm 的剂量下，未观察到跗骨结缔组织或睑板腺的破坏。组织学显示，照射后围绕腺体的胶原网络更加紧密。在 45J/cm 的剂量下，组织学显示围绕腺体的富含胶原的致密网络和睑板细胞发生了严重破坏。
该研究表明，导致组织变硬的跗骨胶原照射应在 10 至 15J/cm 的剂量范围内进行，这一区域被认为是安全的。暴露时间可以根据外科医生的决定进行调整。建立了安全的照射条件，可用于将体外绵羊跗骨暴露于中波紫外线辐射，作为治疗人类患者眼睑松弛的有效方法。
