Errors in laser spot size in laser trabeculoplasty.
By microscopic examination of 50-micron laser burns made on orange paper at different eye-piece settings of the slit-lamp microscope, 27 commercial argon lasers were evaluated for accuracy of 50-micron spot size and for coincidence of the aerial focal points of the laser and the microscope. Only four lasers (14%) produced a spot less than 70 microns diameter (double the area of a 50-micron spot) with the eye-pieces set on zero. With the eye-pieces focussed for minimum spot size, 12 lasers (44%) still gave a minimum spot of 70 microns or more, and four of those gave a spot of 100 microns or more. Improperly focussed lasers and oversize laser spots are a major problem in laser trabeculoplasty.
D006801:Humans; D007834:Lasers / Q000379:methods* / Q000592:standards; D014129:Trabecular Meshwork / Q000601:surgery*