Temperaturgeregelte Laserbestrahlung der Netzhaut des Auges
Medizinische Physik, Biomedizinische Technik
Zusammenfassung der Projektergebnisse
Laser photocoagulation (LPC) is a standard therapy for a variety of retinal diseases such as diabetic macular edema (DME) and diabetic retinopathy. Here, a major challenge is the adjustment of proper light dosing owing to strong absorption variations across the retina, changing light scattering within the eye and small involuntary eye movements (microsaccades). In current clinical practice, the physician adjusts the laser power for subsequent lesions according to the visibility of the previous ones after the typical irradiation time of 50-200 ms. However, this is a cumbersome and timeconsuming procedure, which often leads to unsatisfactory results. Furthermore, recent studies show that a complete denaturation of the retina as in LPC is not necessary for a therapeutic benefit, e.g., in DME or central serous retinopathy, and that very mild coagulation or non-cell-lethal hyperthermia are sufficient. In these cases, the spots remain invisible to the clinician making proper dosing very challenging. Hence, accurate control of the laser power for the intended temperature rise based on real-time measurements would greatly improve irradiation and therapy. In our previous work, the so far only method for real-time retinal temperature determination was developed based on the optoacoustic effect. The main goal of this project was to develop closed-loop automatic control strategies based on this methodology, which guarantee an accurate realization of the desired treatment temperature predetermined by the ophthalmologist. Within this project, significant progress has been made in this direction. In particular, a new experimental setup has been developed using only one high-repetition-rate laser (both for heating and exciting the temperature-dependent pressure waves). On the algorithmic side, parametric model-reduction techniques were developed further to obtain models suitable for real-time control. Moreover, different state and parameter estimators were tailored to LPC, and very promising closed-loop results using model predictive control (MPC) were achieved. These were also extensively evaluated and validated using porcine eye explants. As an outcome of the project, six peer-reviewed publications have been obtained, and one more is currently under review.
Projektbezogene Publikationen (Auswahl)
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Modeling and parameter identification for real-time temperature controlled retinal laser therapies. at - Automatisierungstechnik, 68(11), 953-966.
Kleyman, Viktoria; Gernandt, Hannes; Worthmann, Karl; Abbas, Hossam S.; Brinkmann, Ralf & Müller, Matthias A.
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State and parameter estimation for model-based retinal laser treatment. IFAC-PapersOnLine, 54(6), 244-250.
Kleyman, Viktoria; Schaller, Manuel; Wilson, Mitsuru; Mordmüller, Mario; Brinkmann, Ralf; Worthmann, Karl & Müller, Matthias A.
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Towards temperature controlled retinal laser treatment with a single laser at 10 kHz repetition rate. Advanced Optical Technologies, 10(6), 423-431.
Mordmüller, Mario; Kleyman, Viktoria; Schaller, Manuel; Wilson, Mitsuru; Theisen-Kunde, Dirk; Worthmann, Karl; Müller, Matthias A. & Brinkmann, Ralf
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Model predictive control for retinal laser treatment at 1 kHz. at - Automatisierungstechnik, 70(11), 992-1002.
Schaller, Manuel; Kleyman, Viktoria; Mordmüller, Mario; Schmidt, Christian; Wilson, Mitsuru; Brinkmann, Ralf; Müller, Matthias A. & Worthmann, Karl
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Parameter estimation and model reduction for model predictive control in retinal laser treatment. Control Engineering Practice, 128, 105320.
Schaller, Manuel; Wilson, Mitsuru; Kleyman, Viktoria; Mordmüller, Mario; Brinkmann, Ralf; Müller, Matthias A. & Worthmann, Karl
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State and Parameter Estimation for Retinal Laser Treatment. IEEE Transactions on Control Systems Technology, 31(3), 1366-1378.
Kleyman, Viktoria; Schaller, Manuel; Mordmüller, Mario; Wilson, Mitsuru; Brinkmann, Ralf; Worthmann, Karl & Müller, Matthias A.
