Burri Christian, Salzmann Simon, Amstutz Mylène, Hoffmann Leonie, Považay Boris, Meier Christoph, Frenz Martin
Biomedical Photonics Group, University of Bern, Sidlerstrasse 5, 3012 Bern, Switzerland.
Institute for Human Centered Engineering (HuCE)-OptoLab, Bern University of Applied Sciences, Quellgasse 21, 2501 Biel, Switzerland.
Life (Basel). 2023 Jun 2;13(6):1314. doi: 10.3390/life13061314.
Optical microsurgery confined to the retinal pigment epithelium (RPE) requires locally optimized laser parameters and reliable real-time feedback dosimetry (RFD) to prevent unwanted neuroretinal overexposure. This study aimed to compare pulses of different durations and application modes (single, ramp, burst). Moreover, optical coherence tomography (OCT)-based RFD was investigated in an ex vivo experiment, utilizing nine porcine eyes that were exposed to laser pulses of 8, 12, 16 and 20 µs duration (wavelength: 532 nm, exposure area: 90 × 90 µm, radiant exposure: 247 to 1975 mJ/µm). Simultaneously, time-resolved OCT M-scans were recorded (central wavelength: 870 nm, scan rate: 85 kHz) for RFD. Post irradiation, retinal changes were assessed with color fundus photography (CFP) and cross-sectional OCT B-scans. RPE cell damage was quantified via fluorescence-based cell viability assay and compared to the OCT dosimetry feedback. Our experiments indicate cumulative RPE damage for pulse bursts of 16 µs and 20 µs, whereas no cumulative effects were found for pulse durations of 8 µs and 12 µs applied in ramp mode. According to statistical analysis, OCT-RFD correctly detected RPE cell damage with 96% sensitivity and 97% specificity using pulses of 8 µs duration in ramp mode.
局限于视网膜色素上皮（RPE）的光学显微手术需要局部优化的激光参数和可靠的实时反馈剂量测定法（RFD），以防止不必要的神经视网膜过度暴露。本研究旨在比较不同持续时间和应用模式（单脉冲、斜坡脉冲、脉冲串）的脉冲。此外，在一项离体实验中研究了基于光学相干断层扫描（OCT）的RFD，该实验使用了九只猪眼，使其暴露于持续时间为8、12、16和20微秒的激光脉冲下（波长：532纳米，暴露面积：90×90微米，辐射暴露：247至1975毫焦/微米）。同时，记录时间分辨OCT M扫描（中心波长：870纳米，扫描速率：85千赫）以进行RFD。照射后，用彩色眼底照相（CFP）和横断面OCT B扫描评估视网膜变化。通过基于荧光的细胞活力测定法对RPE细胞损伤进行定量，并与OCT剂量测定反馈进行比较。我们的实验表明，16微秒和20微秒的脉冲串会造成RPE累积损伤，而在斜坡模式下应用的8微秒和12微秒脉冲持续时间未发现累积效应。根据统计分析，使用斜坡模式下8微秒持续时间的脉冲时，OCT-RFD以96%的灵敏度和97%的特异性正确检测到RPE细胞损伤。
