Sanders Talia, Pujara Tarak, Camelo Serge, Lai Ching Tat, Van Saarloos Paul, Beazley Lyn, Rodger Jennifer
Experimental and Regenerative Neurosciences, School of Animal Biology, University of Western Australia, Western Australia, Australia.
Cornea. 2009 May;28(4):434-40. doi: 10.1097/ICO.0b013e31818c2c89.
Corneal refractive surgery is typically performed using a 193-nm excimer laser. However, a recently developed 213-nm solid-state (5th harmonic) Nd:YAG laser presents some practical and user safety advantages, although the biological impact of using this wavelength remains poorly characterized. Here, we provide in vivo and in vitro comparisons of the corneal cellular outcomes after irradiation with 213 and 193 nm wavelengths.
New Zealand White rabbits underwent photorefractive keratectomy with -5 diopters and a 6.5-mm optical zone and studied at time points up to 1 year. The development of haze was examined ophthalmologically and by detecting myofibroblasts immunohistochemically. Cell death was quantified using a terminal deoxynucleotidyl transferase-dUTP nick end labeling (TUNEL) assay, and the number of stromal keratocytes undergoing apoptosis estimated histologically. Superoxide dismutase activity was estimated in vitro by enzyme-linked immunosorbent assay in irradiated rabbit corneal keratocytes.
Our results demonstrate subtle differences in the cellular outcomes after irradiation with 213- and 193-nm lasers, despite similar degrees of corneal haze developing in both treatment groups. In vivo, the 213-nm laser results in more stable stromal cell numbers, implying a more predictable ablation outcome. In vitro, higher levels of superoxide dismutase in corneal keratocytes irradiated with 213 nm compared with 193 nm wavelengths suggest a better endogenous protection against free radicals induced by laser surgery.
The more favorable cellular responses after irradiation with 213 nm compared with 193 nm wavelengths are consistent with good clinical outcomes previously reported. Ablation with a 213 nm wavelength may result in better wound healing, leading to a more reliable correction of refractive errors.
角膜屈光手术通常使用193纳米的准分子激光进行。然而，最近开发的213纳米固态（第五谐波）Nd:YAG激光具有一些实际和用户安全优势，尽管使用该波长的生物学影响仍未得到充分表征。在此，我们提供了213纳米和193纳米波长照射后角膜细胞结果的体内和体外比较。
新西兰白兔接受了-5屈光度和6.5毫米光学区的光性屈光性角膜切削术，并在长达1年的时间点进行研究。通过眼科检查和免疫组织化学检测成肌纤维细胞来检查 haze 的发展。使用末端脱氧核苷酸转移酶-dUTP 缺口末端标记（TUNEL）测定法对细胞死亡进行定量，并通过组织学估计经历凋亡的基质角膜细胞数量。通过酶联免疫吸附测定法在照射的兔角膜角膜细胞中体外估计超氧化物歧化酶活性。
我们的结果表明，尽管两个治疗组中角膜 haze 的发展程度相似，但213纳米和193纳米激光照射后细胞结果存在细微差异。在体内，213纳米激光导致基质细胞数量更稳定，这意味着消融结果更可预测。在体外，与193纳米波长相比，213纳米照射的角膜角膜细胞中超氧化物歧化酶水平更高，这表明对激光手术诱导的自由基具有更好的内源性保护。
与193纳米波长相比，213纳米照射后更有利的细胞反应与先前报道的良好临床结果一致。使用213纳米波长进行消融可能导致更好的伤口愈合，从而更可靠地矫正屈光不正。
