Retinal Laser Lesion Visibility in Simultaneous Ultra-High Axial Resolution Optical Coherence Tomography

Steiner, Patrick; Enzmann, Volker; Meier, Christoph; Považay, Boris; Kowal, Jens

doi:10.1109/jphot.2014.2374594

Cited by 13 publications

(8 citation statements)

References 25 publications

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“…The OCT system used for data acquisition shown in Fig. 2a features a line scan frequency of 70 kHz and a spectral bandwidth of 170 nm centered at 830 nm (EBS8C10, Exalos AG, Switzerland), leading to an axial resolution of 1.78 m in air and is described in detail elsewhere [17]. While a Fourier-domain OCT system was used for the experiments in this paper, any type of OCT system (e.g., time domain, swept source) could be used instead, as long as the system parameters are properly set.…”

Section: System Overviewmentioning

confidence: 99%

Automatic assessment of time-resolved OCT images for selective retina therapy

et al. 2016

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Purpose In recent years, selective retina laser treatment (SRT), a sub-threshold therapy method, avoids widespread damage to all retinal layers by targeting only a few. While these methods facilitate faster healing, their lack of visual feedback during treatment represents a considerable shortcoming as induced lesions remain invisible with conventional imaging and make clinical use challenging. To overcome this, we present a new strategy to provide location-specific and contact-free automatic feedback of SRT laser applications.Methods We leverage time-resolved optical coherence tomography (OCT) to provide informative feedback to clinicians on outcomes of location-specific treatment. By coupling an OCT system to SRT treatment laser, we visualize structural changes in the retinal layers as they occur via time-resolved depth images. We then propose a novel strategy for automatic assessment of such time-resolved OCT images. To achieve this, we introduce novel image features for this task that when combined with standard machine learning classifiers yield excellent treatment outcome classification capabilities.Results Our approach was evaluated on both ex vivo porcine eyes and human patients in a clinical setting, yielding performances above 95 % accuracy for predicting patient treatment outcomes. In addition, we show that accurate outcomes for human patients can be estimated even when our method is trained using only ex vivo porcine data.Conclusion The proposed technique presents a much needed strategy toward noninvasive, safe, reliable, and repeatable SRT applications. These results are encouraging for the broader use of new treatment options for neovascularization-based retinal pathologies.

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Section: System Overviewmentioning

confidence: 99%

Automatic assessment of time-resolved OCT images for selective retina therapy

et al. 2016

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“…An alternative dosimetry approach is to use spectral-domain optical coherence tomography (SD-OCT) simultaneously with SRT to observe MBF formation. This method was described first by Steiner et al, who indirectly detected tissue effects of laser pulses as signal changes in time-resolved SD-OCT A-scans (M-scans), which correspond to a change in the local reflectivity of tissue [24][25][26]. The detailed origin of this signal loss is still debated, but the currently favored hypothesis explains it as "coherent fringe washouts" resulting from the axial motion of the retina due to MBF.…”

Section: Introductionmentioning

confidence: 99%

Dynamic OCT Signal Loss for Determining RPE Radiant Exposure Damage Thresholds in Microsecond Laser Microsurgery

et al. 2021

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Optical microsurgery of the retinal pigment epithelium (RPE) requires reliable real-time dosimetry to prevent unwanted overexposure of the neuroretina. The system used in this experiment implements optical coherence tomography (OCT) to detect the intentional elimination of RPE cells. We evaluated the performance of OCT dosimetry in terms of its ability to detect RPE cell damage caused by microsecond laser pulses of varying duration. Therefore, ex-vivo porcine RPE choroid sclera explants were embedded in an artificial eye and exposed to single laser pulses of 2–20 µs duration (wavelength: 532 nm, exposure area: 120 × 120 µm2, intensity modulation factor: 1.3). Simultaneously, time-resolved OCT M-scans were recorded (central wavelength: 870 nm, scan rate: 33 kHz). Post-irradiation, RPE cell damage was quantified using a calcein-AM viability assay and compared with an OCT-dosimetry algorithm. The results of our experiments show that the OCT-based analysis successfully predicts RPE cell damage. At its optimal operating point, the algorithm achieved a sensitivity of 89% and specificity of 94% for pulses of 6 µs duration and demonstrated the ability to precisely control radiant exposure of a wide range of pulse durations towards selective real-time laser microsurgery.

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“…Pre-clinical studies could show that the signal changes in OCT M-scans during SRT allow real-time prediction of retinal lesions [33,86,88,90,91] also found in clinical experiments. Figure 11.10 demonstrates sub-visual (no visible coagulation spot in the fundus image e) in vivo treatment with clear response in the OCT scan in addition to a brightening in the fundus fluorescence angiography (FFA) scan after application of a 30 times pulse burst sequence at ~160 mJ/ cm 2 fluence per pulse applied at 100 Hz repetition rate and 250 ns pulse length.…”

Section: First Pre-clinical and Clinical Studiesmentioning

confidence: 97%