Lubatschowski H, Kermani O
Institut für Angewandte Physik, Universität Bonn.
Ophthalmologe. 1992 Apr;89(2):134-8.
In order to estimate the photomutagenic and phototoxic potential involved we analyzed the spectrum and intensity of secondary radiation induced with a 193 nm excimer laser in photoablation of corneal tissue. The spectrum of secondary radiation was analyzed by an optical multichannel analyzer. A pyroelectrical detector was used to evaluate the energy of the secondary radiation. We found the secondary radiation to be in the range of ultraviolet to infrared. The spectrum has a relatively high quantity (20%) of radiation between 240 and 280 nm. The intensity of the secondary radiation depends on the energy fluence of the primary laser pulse and can reach a quantum yield of up to 10(-3) (at 800 mJ/cm2). At a fluence of 230 mJ/cm2 (193 nm), the secondary radiation in the range of 240-280 nm is approximately 5 microJ/cm2. Radiation below 300 nm was not transmitted through the cornea. Since the high genetic activity of UV radiation in the range from 240-280 nm is well known, evaluation of the potential mutagenicity of 193 nm excimer laser radiation should take into consideration the presence of secondary radiation in this problematic spectral range. However, there is no incidence known for specific UV-induced corneal cancers, which supports the argument that the potential mutgenic risk of clinical excimer laser application can be considered to be low. Because of the full corneal absorption of radiation below 300 nm, there is no risk known for pigmented intraocular structures.
为了评估其中涉及的光致突变和光毒性潜力，我们分析了193nm准分子激光在角膜组织光消融过程中诱导产生的二次辐射的光谱和强度。二次辐射的光谱由光学多通道分析仪进行分析。使用热释电探测器来评估二次辐射的能量。我们发现二次辐射的范围在紫外到红外之间。该光谱在240至280nm之间有相对较高比例（20%）的辐射。二次辐射的强度取决于初级激光脉冲的能量通量，并且在800mJ/cm²时量子产率可达10⁻³。在230mJ/cm²（193nm）的通量下，240 - 280nm范围内的二次辐射约为5μJ/cm²。波长低于300nm的辐射无法透过角膜。由于240 - 280nm范围内的紫外线具有较高的遗传活性，在评估193nm准分子激光辐射的潜在诱变性时，应考虑在这个有问题的光谱范围内存在二次辐射。然而，目前尚无特定紫外线诱导的角膜癌病例报道，这支持了临床应用准分子激光的潜在诱变风险可被认为较低的观点。由于角膜对波长低于300nm的辐射完全吸收，因此对于眼内色素结构不存在已知风险。
