Laser trabecular ablation (LTA)

As part of a pilot study for glaucoma surgery, the use of 3 infrared solid state lasers with 4 fiber optic delivery systems to ablate human trabecular meshwork was investigated. Laser trabecular ablation (LTA) was attempted with the Erbium:YAG (2.94 μm), Erbium:YSGG (2.79 μm), and Holmium:YSGG (2.1 μm) lasers. Laser energy was delivered as a single pulse (250 μs) by tissue fiber optic contact with low hydroxyl-fused silica (200 and 500 μm), zirconium fluoride (250 μm), or sapphire (250 μm) fiber optics. Total energy required and thermal effects decreased as laser wavelength increased. LTA was best achieved at 2.94 μm (4 mJ total energy; energy densities = 8.2–12.7 J/cm2; pulse length 250 μs) with average thermal damage zones of 5.3–10.3 ± 1.3–2.4 μm (means ± SDs) to contiguous structures. This finding has potential applications in the surgical treatment of open-angle and congenital glaucoma and may minimize failure rates seen in other types of surgery on the trabecular meshwork where disrupted trabecular meshwork is not removed.