Laser sclerostomy by pulsed-dye laser and goniolens
M. A. Latina, M. Dobrogowski, W. F. March and R. Birngruber
Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Boston 02114.
We describe an ab-interno laser sclerostomy procedure using the method
termed dye-enhanced ablation with a slit-lamp delivery system and special
goniolens such that only the laser light beam penetrates the anterior
chamber. The procedure uses a microsecond-pulsed-dye laser emitting at 666
nm and iontophoresis of methylene blue dye (absorption of 668 nm) into the
sclera at the limbus to enhance the absorption of the laser light. We
compared the number of pulses needed to perforate excised human sclera at
pulse durations of 1.5, 20, and 300 microseconds. Pulse durations of 1.5
and 20 microseconds required 20 pulses or fewer to perforate excised human
sclera with pulse energies of 75 to 100 mJ. The ab-interno laser
sclerostomy procedure was performed in 54 eyes of Dutch-belted rabbits with
pulse durations of 1.5 or 20 microseconds and a 100- or 200-microns
incident spot diameter delivered using a CGF goniolens. Full-thickness
fistulas were successfully created at both pulse durations in approximately
80% of eyes treated. A range of three to 25 pulses was required to
perforate sclera with slightly fewer pulses and lower pulse energies at 1.5
microseconds compared with 20 microseconds. There were no significant
complications from the procedure. This technique could permit filtration
surgery to be performed on an outpatient basis.
