Ab-interno erbium (Er):YAG laser sclerostomy with iridotomy in Dutch cross rabbits

An ab-interno technique using a pigmented rabbit model has been developed that uses a pulsed erbium:YAG laser to create an iridotomy with a sclerostomy through the same corneal incision. Laser energy was delivered with an articulated arm terminating in side-firing (850 or 650 microns OD) or end-firing (850 or 400 microns OD) fiber optic endoprobes, which allowed iridotomies and sclerostomies, respectively, to be created. Initially, sclerostomies (8-10, 8 mJ/300 microseconds pulses) and basal iridotomies (1-3, 4 mJ/200 microseconds pulses) were created with the larger probes. Problems encountered with this technique included corneal decompensation and rapid formation of peripheral anterior synechiae with occlusion of sclerostomies. The smaller endoprobes were then used to create mid-peripheral iridotomies and sclerostomies utilizing the same energy parameters. Sclerostomies created in this manner remained patent in the first postoperative week until the animals were sacrificed to obtain material for histologic study.