Wood John P M, Plunkett Malcolm, Previn Victor, Chidlow Glyn, Casson Robert J
South Australian Institute of Ophthalmology, Ophthalmic Research Laboratories, Level 2 Hanson Institute, IMVS, Adelaide, South Australia, Australia.
Lasers Surg Med. 2011 Aug;43(6):499-510. doi: 10.1002/lsm.21087.
Thermal lasers are routinely used to treat certain retinal disorders although they cause collateral damage to photoreceptors. The current study evaluated a confined, non-conductive thermal, 3-nanosecond pulse laser in order to determine how to produce the greatest therapeutic range without causing collateral damage. Data were compared with that obtained from a standard thermal laser.
Porcine ocular explants were used; apposed neuroretina was also in place for actual laser treatment. After treatment, the retina was removed and a calcein-AM assay was used to assess retinal pigmented epithelium (RPE) cell viability in the explants. Histological methods were also employed to examine lased transverse explant sections. Three nanoseconds pulse lasers with either speckle- or gaussian-beam profile were employed in the study. Comparisons were made with a 100 milliseconds continuous wave (CW) 532 nm laser. The therapeutic energy range ratio was defined as the minimum visible effect threshold (VET) versus the minimum detectable RPE kill threshold.
The 3-nanosecond lasers produced markedly lower minimum RPE kill threshold levels than the CW laser (e.g., 36 mJ/cm(2) for speckle-beam and 89 mJ/cm(2) for gaussian-beam profile nanosecond lasers vs. 7,958 mJ/cm(2) for CW laser). VET values were also correspondingly lower for the nanosecond lasers (130 mJ/cm(2) for 3 nanoseconds speckle-beam and 219 mJ/cm(2) for gaussian-beam profile vs. 1,0346 mJ/cm(2) for CW laser). Thus, the therapeutic range ratios obtained with the nanosecond lasers were much more favorable than that obtained by the CW laser: 3.6:1 for the speckle-beam and 2.5:1 for the gaussian-beam profile 3-nanosecond lasers versus 1.3:1 for the CW laser.
Nanosecond lasers, particularly with a speckle-beam profile, provide a much wider therapeutic range of energies over which RPE treatment can be performed, without damage to the apposed retina, as compared with conventional CW lasers. These results may have important implications for the treatment of retinal disease.
热激光常用于治疗某些视网膜疾病，尽管它们会对光感受器造成附带损伤。本研究评估了一种受限的、非传导性热3纳秒脉冲激光，以确定如何在不造成附带损伤的情况下产生最大的治疗范围。将数据与从标准热激光获得的数据进行比较。
使用猪眼外植体；在实际激光治疗时，紧贴的神经视网膜也在位。治疗后，取出视网膜，使用钙黄绿素-AM测定法评估外植体中视网膜色素上皮（RPE）细胞的活力。还采用组织学方法检查激光照射后的外植体横向切片。本研究采用具有散斑或高斯光束轮廓的3纳秒脉冲激光。与100毫秒连续波（CW）532纳米激光进行比较。治疗能量范围比定义为最小可见效应阈值（VET）与最小可检测RPE杀伤阈值之比。
3纳秒激光产生的最小RPE杀伤阈值水平明显低于连续波激光（例如，散斑光束的为36 mJ/cm²，高斯光束轮廓的纳秒激光为89 mJ/cm²，而连续波激光为7958 mJ/cm²）。纳秒激光的VET值也相应较低（3纳秒散斑光束的为130 mJ/cm²，高斯光束轮廓的为219 mJ/cm²，而连续波激光为10346 mJ/cm²）。因此，纳秒激光获得的治疗范围比远优于连续波激光：散斑光束的为3.6:1，高斯光束轮廓的3纳秒激光为2.5:1，而连续波激光为1.3:1。
与传统连续波激光相比，纳秒激光，尤其是具有散斑光束轮廓的纳秒激光，提供了更宽的能量治疗范围，在此范围内可以进行RPE治疗而不损伤紧贴的视网膜。这些结果可能对视网膜疾病的治疗具有重要意义。
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