Real-time optical coherence tomography observation of retinal tissue damage during laser photocoagulation therapy on ex-vivo porcine samples

Steiner, Patrick; Považay, Boris; Stoller, Markus; Morgenthaler, P.; Inniger, D.; Arnold, Patrik; Sznitman, Raphael; Meier, Ch.

doi:10.1364/ecbo.2015.95410q

Cited by 5 publications

(5 citation statements)

References 15 publications

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“…With its optical access, OCT can image the three-dimensional structure and comfortably discriminate the level of RPE lesions 13 indirectly as a change of signal strength 15 . This method was described by Steiner et al 16,17,18,19 ; effects of treatment laser pulses were indirectly detected as a change of intensity in axial OCT scans (A-scans), which correspond to the local reflectivity of tissue. Using signal changes of OCT M-scans, Kaufmann et al 15,20 were able to precisely predict real-time retinal lesions during SRT.…”

Section: Introductionmentioning

confidence: 99%

Optical coherence tomography controlled selective retina therapy with a novel microsecond laser

Burri¹,

Hutfilz²,

Grimm³

et al. 2019

Medical Laser Applications and Laser-Tissue Interactions IX

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Selective retina therapy (SRT) is a short pulse (µs-regime) alternative to conventional laser photocoagulation (LPC) for treatment of retinal diseases. LPC leads to collateral damage of retinal layers adjacent to the retinal pigment epithelium (RPE), including healthy, non-regenerative photoreceptors due to the high thermal load, whereas in SRT, RPE cells are destroyed by microbubbles without damaging the neuronal retina. A novel experimental SRT laser operating at 532 nm wavelength can deliver 2 -20 μs pulse sequences. Its tight integration into an upgraded diagnostic SPECTRALIS system combines beam control for treatment planning with real-time optical coherence tomography (OCT) overexposure protection of the photoreceptors. This "Spectralis Centaurus" system, was built and preliminary tested on porcine ex-vivo samples, reaching an unprecedented accuracy with unique planning and follow-up capabilities for upcoming clinical cellular level micro-surgery. The combination of OCT with SRT selectively limits cell death to the RPE by precisely controlling energy deposition while optically monitoring tissue response.

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Section: Introductionmentioning

confidence: 99%

Optical coherence tomography controlled selective retina therapy with a novel microsecond laser

Burri¹,

Hutfilz²,

Grimm³

et al. 2019

Medical Laser Applications and Laser-Tissue Interactions IX

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“…Furthermore, Schuele et al were able to show that using laser pulses of 5 µs duration RPE cell damage was always associated with MBF, whereas at pulses of 50 µs duration, thermal denaturation takes over but does not fully replace microbubble formation [ 49 ]. Complementarily, Lee et al were able to show that by using pulses of 1, 5 and 10 µs duration, more than 95% of dead RPE cells were associated with MBF, whereas the ratio decreased to 65% and 45% for longer 20 µs and 40 µs pulses, respectively [ 30 ]. The presented results from this study underline these findings.…”

Section: Discussionmentioning

confidence: 99%

“…An attractive dosimetry approach is the utilization of spectral-domain optical coherence tomography (SD-OCT) simultaneously with SRT. This method was first described by Steiner et al, who indirectly detected tissue effects of laser pulses as signal loss (coherent fringe washout) in time-resolved SD-OCT A-scans (M-scans) [ 28 , 29 , 30 ]. The detailed mechano-optical model of the signal loss during laser treatment is still debated, but the currently favored hypothesis explains it as interference signal contrast loss, or decorrelation, also known as “fringe washout” resulting from the axial motion or other signal alterations of retinal surfaces due to MBF within time scales close to, or above, the coherent acquisition time of the depth scan [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Influence of Pulse Duration and Application Mode on Microsecond Laser Microsurgery of the Retinal Pigment Epithelium

Burri,

Salzmann,

Amstutz

et al. 2023

Life

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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 µm2, radiant exposure: 247 to 1975 mJ/µm2). 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.

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“…Thermal tissue expansion and scattering changes were assessed in time-resolved OCT A-scans (M-scans). For SRT, a similar method was described by Steiner et al, who indirectly detected tissue effects of laser pulses as OCT-signal loss in OCT M-scans [ 43 – 45 ]. The detailed mechano-optical model of the signal loss during laser treatment is still debated, but the currently favored hypothesis explains it as interference signal contrast loss, or decorrelation, also known as “coherence fringe washout” resulting from the fast motion or other signal alterations of the monitored retinal surfaces due to MBF within time scales of and above the coherent acquisition time of the depth scan [ 46 ].…”

Section: Introductionmentioning

confidence: 99%

Real-time OCT feedback-controlled RPE photodisruption in ex vivo porcine eyes using 8 microsecond laser pulses

Burri,

Salzmann,

Wandel

et al. 2023

Biomed. Opt. Express

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Selective retinal pigment epithelium (RPE) photodisruption requires reliable real-time feedback dosimetry (RFD) to prevent unwanted overexposure. In this study, optical coherence tomography (OCT) based RFD was investigated in ex vivo porcine eyes exposed to laser pulses of 8 µs duration (wavelength: 532 nm, exposure area: 90 × 90 µm2, radiant exposure: 247 to 1975 mJ/µm2). For RFD, fringe washouts in time-resolved OCT M-scans (central wavelength: 870 nm, scan rate: 85 kHz) were compared to an RPE cell viability assay. Statistical analysis revealed a moderate correlation between RPE lesion size and applied treatment energy, suggesting RFD adaptation to inter- and intraindividual RPE pigmentation and ocular transmission.

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Real-time optical coherence tomography observation of retinal tissue damage during laser photocoagulation therapy on ex-vivo porcine samples

Cited by 5 publications

References 15 publications

Optical coherence tomography controlled selective retina therapy with a novel microsecond laser

Optical coherence tomography controlled selective retina therapy with a novel microsecond laser

Investigation of the Influence of Pulse Duration and Application Mode on Microsecond Laser Microsurgery of the Retinal Pigment Epithelium

Real-time OCT feedback-controlled RPE photodisruption in ex vivo porcine eyes using 8 microsecond laser pulses

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