Therapeutical bandwidth of selective rpe-photocoagulation treatment by repetitive fis-laser pulses <527 nm - first clinical results

Johann Roider, Ralf Brinkmann, Horst Laqua, Reginald Birngruber


Purpose: Selective RPE photocoagulation with sparing the photoreceptors has been demonstrated by repetitive l|js, 5 us and 200 ns short laser pulses at 514 nm and 532 nm in animal experiments We are performing a first clinical study treating central serous retmopathy, diabetic macular edema, and early proliferative diabetic retinopathy as well as drusen. In this clinical study the acute effects and the therapeutical bandwidth of this new treatmenl are investigated Methods: We are using a Nd YLF laser (527 nm}: Exposure parameters were as follows pulse duration 1-2 us, repetition rate 500 Hz, number of pulses applied: 500, spot size: 158 urn. Energy was judged after performing test exposures and evaluation of a an immediate post operative fluorescem angiogram After the test exposures the true therapeutical selective RPE treatment was performed. Results. In humans more energy is necessary than in animals (a factor of 5-10 difference). Similar to the animal experiments with 200 ns pulses even with energies, which lead to blanching of the retina, no disruptive effects could be observed. Energies, which lead to a selective RPE effect, show a different fluorescein pattern than conventional cw-tmld retinal photocoagulation While cwphotocoagulation effects show a distinction of the chonocapillans resulting in early non perfusion in fluorescein angiogram. no such effects are detected after selective RPE photocoagulation. Selective RPE phoiocaoagulation effects are only detectable in the late stage of the flourescein angiogram In opposite to conventional very mild cw photocoagulation effects the selective RPE photcoagulation effects could not be detected by infrared imaging Micopenmetry underlines the selectivity of the effects. Further results of the ongoing clinical study will be presented Conclusion: Selective RPE photocoagulation with repetitive 1-2 us laser pulses is possible and safe in humans No acute adverse effects were detected up lo now.

Original languageEnglish
JournalInvestigative Ophthalmology and Visual Science
Issue number4
Pages (from-to)S83
Publication statusPublished - 1997

Research Areas and Centers

  • Academic Focus: Biomedical Engineering


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