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Steps to optimize transscleral photocoagulation

  • P.-R. Preuβner
  • O. Schwenn
Laboratory Investigation

Abstract

•Background: In transscleral photocoagulation, the desired effect is coagulation of parts of the ciliary body or of the peripheral retina. However, the application is often limited by the unwanted effect of coagulation of the sclera. to reduce this effect, the ratio of incident radiation flux to radiation flux transported through the sclera (and able to coagulate the target tissue) should be minimized by the incident beam characteristics.

•Methods: Monte Carlo simulations for the radiation transport problem of multiple scattering in the sclera were used to calculate the ratio of transported to incident radiation for different parameter settings of beam diameters, optical thicknesses of the sclera and beam angles. To verify the theoretical calculations, an simple optical device utilizing a bulb instead of a laser source was constructed and applied to enucleated porcine eyes.

•Results: The theoretical calculations showed that the ratio of incident to transported radiation flux can typically be decreased by a factor of three by increasing the beam radius from 0.35 mm (as used in state-of-the-art laser devices) to 2 mm. This was confirmed by the experiments. Coagulations of the ciliary body or of the peripheral retina were possible with power densities an order of magnitude below the values normally applied with laser sources.

•Conclusion: To improve transscleral photocoagulation, beam diameters should be increased.

Key words

Transscleral cyclophotocoagulation Transscleral retinal coagulation Radiation transport Monte Carlo calculation 

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Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • P.-R. Preuβner
    • 1
  • O. Schwenn
    • 1
  1. 1.Universitäts-AugenklinikMainzGermany

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