Abstract

Two prototype intravitreal CO₂ laser probes, one utilizing a KRS-5 optical fiber and the other a hollow waveguide, were used to cut vitreal membranes in rabbits with short pulses (300 μsec to 200 msec) of IR energy. The thresholds for cutting expressed as an energy density were approximately constant (8-9 J/cm²) for short pulses between 300 and 1200 μsec but increased dramatically (45-135 J/cm²) for longer pulses between 30 and 200 msec. Thus it appears that losses due to thermal diffusion during the pulse from the region of absorption (~1/950 cm^-1 or 11 μm thick) are small for pulses below 1 msec and very significant for pulses longer than 30 msec.

© 1983 Optical Society of America