Laser-induced scleral shrinkage for laser scleral buckling: Physical model

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Abstract

Purpose. To develop a physical model of laser-induced scierai shrinkage for laser scierai buckling. Methods. The scierai temperature increase induced with a pulsed Ho:YAG (2.16 urn, 250 us, 5 Hz) and Tm:YAG (2.01|im, 250 us, 5 Hz) laser was calculated as a function of the fluence per pulse and total number of pulses by solving a one-dimensional heat equation. We assumed that scierai shrinkage occurred when the surface temperature reached 65 "C. The number of pulses required to produce scierai shrinkage and the scierai surface temperature were calculated as a function of the fluence per pulse. The predictions of the model were compared with experimental results (Sasoh et al, Invest. Ophth. Vis. Sci., 1995, S845). Results. The scierai surface temperature reaches a maximum value (steady-state) of 24.3 I °C for the Tm:YAG laser and 18.6 I °C for the Ho:YAG laser, where I is the fluence per pulse. At a given fluence per pulse, less pulses were needed to reach the steady-state temperature with the Tm:YAG laser than with the HorYAG laser. The threshold fluences for shrinkage were 2.7 J/cm for the Tm:YAG laser and 3.5 J/cm for the Ho:YAG laser. Conclusions. No shrinkage occurs if the steady-state temperature is lower than the shrinkage temperature. Once the steady-state temperature is reached, additional number of pulses do not induce more shrinkage. The model provides a qualitative description of laser-induced scierai shrinkage which is in good agreement with experimental results. We are currently refining the model to improve its quantitative accuracy.

Original languageEnglish (US)
Pages (from-to)S662
JournalInvestigative Ophthalmology and Visual Science
Volume38
Issue number4
StatePublished - Dec 1 1997

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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