Safety of high-energy neodymium:YAG laser pulses in YAG sclerostomy

Picosecond neodymium:yttrium lithium fluoride laser sclerectomy

The picosecond neodymium:yttrium lithium fluoride laser, a high-power, short-pulse laser that uses low energy per pulse and has a high repetition rate and a highly coherent energy source of 1,053 nm, was used to perform sclerectomies by an ab externo approach in human cadaver eyes. We evaluated laser settings with regard to full-thickness scleral perforation and thermal damage to surrounding tissue. We studied energy per pulse, depth per burst (a present number of spots), spot and line separation of the pattern (spacing between spots of the laser in length [spot separation] and width [line separation]), and total energy required to perforate the sclera. Efficiency was determined by evaluating which settings required the fewest spots and least total energy to perforate the sclera. We studied histologic sections of the sclerectomy sites to determine thermal damage to the surrounding sclera. The picosecond neodymium:yttrium lithium fluoride laser is effective in performing full-thickness sclerectomy with minimal thermal damage to the surrounding tissue. The anterior chamber could be penetrated with an average total energy of 13.3 +/- 0.4 (SEM) J. The sclerectomy size was 545 +/- 11 microns externally and 163 +/- 4 microns internally. Successful sclerectomies were performed with as little as 3 to 5 microns of thermal damage to the surrounding scleral tissue with 250 microJ per pulse.

Silver oxide in YAG sclerostomy

YAG sclerostomy is a filtering procedure performed entirely with the neodymium:YAG laser through a goniolens as an alternative to trabeculectomy in the treatment of glaucoma. Extremely large pulse powers have been required in the past to complete the procedure. We found that an injection of silver-stabilized protein intrasclerally prior to the procedure makes it possible to perform the procedure with low total power.