title: Optoacoustic real-time dosimetry for selective retina treatment.
abstract: The selective retina treatment (SRT) targets retinal diseases associated with disorders in the retinal pigment epithelium (RPE). Due to the ophthalmoscopic invisibility of the laser-induced RPE effects, we investigate a noninvasive optoacoustic real-time dosimetry system. In vitro porcine RPE is irradiated with a Nd:YLF laser (527 nm, 1.7-micros pulse duration, 5 to 40 microJ, 30 pulses, 100-Hz repetition rate). Generated acoustic transients are measured with a piezoelectric transducer. During 27 patient treatments, the acoustic transients are measured with a transducer embedded in an ophthalmic contact lens. After treatment, RPE damage is visualized by fluorescein angiographic leakage. Below the RPE damage threshold, the optoacoustic transients show no pulse-to-pulse fluctuations within a laser pulse train. Above threshold, fluctuations of the individual transients among each other are observed. If optoacoustic pulse-to-pulse fluctuations are present, RPE leakage is observed in fluorescein angiography. In 96% of the irradiated areas, RPE leakage correlated with the optoacoustic defined threshold value. A noninvasive optoacoustic real-time dosimetry for SRT is developed and proved in vitro and during patient treatment. It detects the ophthalmoscopically invisible laser-induced damage of RPE cells and overcomes practical limitations of SRT for use in private practice.
authors.affiliation: Medical Laser Center, Lübeck, Germany. gschuele@lumenis.com
authors.forename: Georg
authors.initials: G
authors.lastname: Schuele
authors.forename: Hanno
authors.initials: H
authors.lastname: Elsner
authors.forename: Carsten
authors.initials: C
authors.lastname: Framme
authors.forename: Johann
authors.initials: J
authors.lastname: Roider
authors.forename: Reginald
authors.initials: R
authors.lastname: Birngruber
authors.forename: Ralf
authors.initials: R
authors.lastname: Brinkmann
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D000818:Animals; D003199:Computer Systems; D004307:Dose-Response Relationship, Radiation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D017075:Laser Coagulation / Q000379:methods*; D053685:Laser Therapy; D055095:Optics and Photonics / Q000295:instrumentation*; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology / Q000528:radiation effects* / Q000601:surgery*; D012680:Sensitivity and Specificity; D013552:Swine